MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Heart Rhythm' source. Sun, 21 Mar 2010 14:01:17 +0100 http://www.medworm.com/index.php?rid=3303850&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527110000081%2Fabstract%3Frss%3Dyes Yu et al (N Engl J Med 2009;361:2123–2134; PMID: 19915220) evaluated whether biventricular (BiV) pacing is superior to right ventricular apical (RVA) pacing in preventing deterioration of left ventricular (LV) systolic function and cardiac remodeling in patients with bradycardia and a normal ejection fraction (EF). In this prospective, double-blind, multicenter study, 177 patients with implantation of a BiV pacemaker were randomized to BiV pacing (89 patients) or RVA pacing (88 patients). The primary end points were the LVEF and LV end-systolic volume. At 12 months, the mean LVEF was significantly lower with RVA pacing than in the BiV pacing (54.8+/-9.1% vs. 62.2+/-7.0%, P (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303850 Fri, 29 Jan 2010 00:00:00 +0100 3303850 http://www.medworm.com/index.php?rid=3303849&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS154752711000007X%2Fabstract%3Frss%3Dyes Conclusion: Resurgent currents are associated with multiple channelopathies and are likely to be important contributors to neuronal and muscle disorders of excitability. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303849 Fri, 29 Jan 2010 00:00:00 +0100 3303849 http://www.medworm.com/index.php?rid=3205801&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109014441%2Fabstract%3Frss%3Dyes We are pleased to announce the fifth annual HeartRhythm journal Outstanding Publication Award for Young Electrophysiologists. This educational grant was generously provided by Medtronic, Inc. for investigators within three years of completion of training judged to have published the most outstanding clinical and basic research articles in HeartRhythm. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205801 Tue, 26 Jan 2010 13:54:11 +0100 3205801 http://www.medworm.com/index.php?rid=3205800&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS154752710901443X%2Fabstract%3Frss%3Dyes The Official Journal of the Heart Rhythm Society and the Cardiac Electrophysiology Society In addition to members of the editorial board, Heart Rhythm extends a warm thanks to the following reviewers. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205800 Tue, 26 Jan 2010 13:54:11 +0100 3205800 http://www.medworm.com/index.php?rid=3303839&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527110000500%2Fabstract%3Frss%3Dyes Atrial fibrillation (AF) is common but rarely is life-threatening, yet technological innovation aimed at modification of the arrhythmic substrate has advanced rapidly. In contrast, stroke associated with AF is a common and serious cause of morbidity and mortality, yet the mainstay of stroke prophylaxis in 2010 remains dose-adjusted warfarin, a venerable pesticide approved for human use in the 1950s. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303839 Mon, 25 Jan 2010 00:00:00 +0100 3303839 http://www.medworm.com/index.php?rid=3303841&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527110000020%2Fabstract%3Frss%3Dyes Although the occurrence rate of sudden cardiac death (SCD) has decreased somewhat, in part because of wider use of implantable defibrillators, SCD due to ventricular tachyarrhythmias (VTs) continues to be a significant problem. Ischemic heart disease (IHD) is a major risk factor for SCD, which is in turn a substantial contributor to IHD mortality. Efforts at diminishing the SCD burden in IHD patients include improved risk stratification, as well as the continued assessment of underlying pathophysiology to establish novel mechanistically based therapeutic interventions. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303841 Thu, 07 Jan 2010 00:00:00 +0100 3303841 http://www.medworm.com/index.php?rid=3303851&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109014313%2Fabstract%3Frss%3Dyes I read with interest the paper by Martinek et al entitled “Acute development of gastroesophageal reflux after radiofrequency catheter ablation of atrial fibrillation.” While the authors' concern is the contribution that the development of gastroesophageal reflux may make to atrioesophageal fistulas, I think it is important to realize that reflux disease as a complication of the procedure may present long-term morbidity to the patient. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303851 Mon, 04 Jan 2010 00:00:00 +0100 3303851 http://www.medworm.com/index.php?rid=3303835&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109014775%2Fabstract%3Frss%3Dyes Multiple major clinical trials over the last 2 decades have established the central role of implantable cardioverter defibrillators (ICDs) as a life-saving therapy in patients with ventricular arrhythmias (VA) as well as ischemic and nonischemic cardiomyopathy. Additional benefit is seen when an ICD is combined with cardiac resynchronization therapy (CRT) in heart failure patients. Appropriate shocks have been seen as a life-saving therapy with a sudden cardiac death (SCD) aborted without any other consequences. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303835 Mon, 04 Jan 2010 00:00:00 +0100 3303835 http://www.medworm.com/index.php?rid=3303825&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109014283%2Fabstract%3Frss%3Dyes Since Nademanee et al first reported the utility of ablation of complex fractionated atrial electrograms (CFAEs) for cure of atrial fibrillation (AF), the approach has been widely adopted, particularly in patients with persistent AF. However, despite its widespread clinical use, the definition, significance, and efficacy of ablation of CFAEs remain uncertain. Furthermore, in patients with extensive CFAEs, ablation endpoints are unknown. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303825 Mon, 04 Jan 2010 00:00:00 +0100 3303825 http://www.medworm.com/index.php?rid=3303854&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109014362%2Fabstract%3Frss%3Dyes We thank you for all your interesting comments on our article, “Acute development of gastroesophageal reflux after radiofrequency catheter ablation of atrial fibrillation,” and would like to discuss a few of the aspects that were mentioned. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303854 Thu, 31 Dec 2009 00:00:00 +0100 3303854 http://www.medworm.com/index.php?rid=3303853&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109014350%2Fabstract%3Frss%3Dyes We read with great interest the manuscript of Martinek et al recently published in Heart Rhythm entitled “Acute development of gastroesophageal reflux after radiofrequency catheter ablation of atrial fibrillation.” (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303853 Thu, 31 Dec 2009 00:00:00 +0100 3303853 http://www.medworm.com/index.php?rid=3303852&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109014349%2Fabstract%3Frss%3Dyes We are grateful for all of the interesting comments on our manuscript entitled “Acute development of gastroesophageal reflux after radiofrequency catheter ablation of atrial fibrillation” and would like to discuss a few statements that have been made. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303852 Thu, 31 Dec 2009 00:00:00 +0100 3303852 http://www.medworm.com/index.php?rid=3205832&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013411%2Fabstract%3Frss%3Dyes Tikkanen et al (N Engl J Med 2009 Nov 16 epub PMID: 19917913) assessed the prevalence and prognostic significance of early repolarization on 12-lead electrocardiograms (ECGs) in a community-based general population of 10,864 subjects. Early repolarization was defined as elevation of the QRS-ST junction (J point) in leads other than V(1) through V(3). The primary end point was death from cardiac causes, and secondary end points were death from any cause and death from arrhythmia during a mean follow-up of 30+/−11 years. Early repolarization was stratified according to the degree of J-point elevation (≥=0.1 mV or ≥0.2 mV) in either inferior or lateral leads. The early-repolarization pattern of ≥0.1 mV was present in 630 subjects (5.8%): 384 (3.5%) in inferior leads and 262 (2.4%) in ... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205832 Thu, 31 Dec 2009 00:00:00 +0100 3205832 http://www.medworm.com/index.php?rid=3205831&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013393%2Fabstract%3Frss%3Dyes Schwartz et al (Circulation 2009;120:1761, PMID 19841298) sought to define the prevalence of long QT syndrome (LQTS). The authors studied ECGs of infants from 18 maternity hospitals. Among genotyped infants, disease-causing mutations were found in 12 (43%) of 28 infants with QTc >470 ms and in 4 (29%) of 14 infants with QTc = 461–470 ms. One genotype-negative infant (QTc = 482 ms) was diagnosed as affected by LQTS on clinical grounds. Among family members of genotype-positive infants, 51% were found to carry disease-causing mutations. In total, 17 of 43,080 white infants were affected by LQTS, demonstrating a prevalence of at least 1:2,534 apparently healthy live births. The authors hypothesize that the prevalence might be close to 1:2,000. ECG-guided molecular screening can identify mos... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205831 Wed, 30 Dec 2009 00:00:00 +0100 3205831 http://www.medworm.com/index.php?rid=3125165&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013885%2Fabstract%3Frss%3Dyes HeartRhythm is the Official Journal of the Heart Rhythm Society and the Cardiac Electrophysiology Society. HeartRhythm provides rapid online electronic (3-5 business days) and print publication of the most important current scientific developments in the field of cardiac arrhythmias and electrophysiology. The Journal publishes both clinical and basic original, peer-reviewed articles devoted to the diagnosis and treatment of heart rhythm disorders, as well as the electrophysiology of the heart and blood vessels, including ion channels and biophysics, pharmacology, genetics, modeling, and cellular and in vivo electrophysiology. In general, review articles are invited, but unsolicited submissions will be considered. All articles are peer-reviewed. Articles from the Editor's institution are p... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125165 Tue, 29 Dec 2009 13:52:49 +0100 3125165 http://www.medworm.com/index.php?rid=3125138&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013241%2Fabstract%3Frss%3Dyes The New Year always brings the opportunity for change and the hope that such change will make 2010 better than the year before. We all share that sentiment. For HeartRhythm, last year was filled with comprehensive issues each containing 143 pages of superb articles, plus four outstanding supplements. We debuted a new journal cover, a Chinese edition published quarterly, and received a record 1400 new submissions. Despite the added load, the review time is a steady 8.5 days and the time to first decision less than 10 days. Electronic publication of the PDF after acceptance remains 4 or 5 days, and 3-4 months to print. The acceptance rate fell to less than 20% and the impact factor rose to 4.444, continuing to make HeartRhythm the number one specialty journal in cardiology. The impact facto... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125138 Tue, 29 Dec 2009 13:52:39 +0100 3125138 http://www.medworm.com/index.php?rid=3303846&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013824%2Fabstract%3Frss%3Dyes It is impossible to summarize all advances made in clinical and basic cardiac electrophysiology in 2009. In this article, we have attempted to select and condense the key literature published during the year. We are bound to err both by inclusion and by omission. We apologize to investigators and authors whose worthy contributions are not mentioned because of space and/or our own ignorance, and we welcome the input and criticisms of the Heart Rhythm readership, as these will assist in identifying the directions to be taken in “The Year in Arrhythmias 2010.” What follows is a subjective sample of highlighted articles exemplifying the recent advances in our field. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303846 Fri, 25 Dec 2009 00:00:00 +0100 3303846 http://www.medworm.com/index.php?rid=3303837&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS154752710901385X%2Fabstract%3Frss%3Dyes Heart failure is a common multifactorial disease with substantial morbidity and mortality. The main clinical manifestations of heart failure include limited exercise tolerance, fluid retention with predisposition to edematous states and acute pulmonary edema, and other organ dysfunction such as hepatic and renal insufficiency. Heart failure is associated with a shortened life expectancy, with a median survival of 1.7 years in men and 3.2 years in women according to epidemiologic data from the Framingham Heart Study. A significant cause of mortality in heart failure is sudden cardiac death, in many cases as result of ventricular arrhythmias. Cardiac myocytes from failing hearts exhibit abnormal repolarization suggesting a predisposition to reentrant arrhythmia. Understanding risk factors fo... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303837 Fri, 25 Dec 2009 00:00:00 +0100 3303837 http://www.medworm.com/index.php?rid=3303833&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109014167%2Fabstract%3Frss%3Dyes Because asynchronous electrical activation of ventricular myocardium has detrimental effects on its mechanical function, cardiac resynchronization therapy by means of biventricular (BiV) pacing has been used in heart failure patients. Due to the positive effects of BiV pacing in patients with heart failure and intrinsic or right ventricular (RV) pacing-induced left bundle branch block (LBBB), other applications have been sought and suggested. However, failure of studies such as RethinQ (Cardiac-Resynchronization Therapy in Heart Failure with Narrow QRS Complexes) indicate that application of pacing should always be guided by considering the effect of the specific ventricular pacing site(s) and mode on ventricular activation, mechanics, and hemodynamics. After all, in hearts with normal imp... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303833 Fri, 25 Dec 2009 00:00:00 +0100 3303833 http://www.medworm.com/index.php?rid=3125164&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012600%2Fabstract%3Frss%3Dyes Roux et al (Circulation 2009;120:1036–1040, PMID 19738139) evaluated if empirical antiarrhythmic drug (AAD) therapy for 6 weeks after atrial fibrillation (AF) ablation reduced atrial arrhythmias. Among 110 consecutive paroxysmal AF patients undergoing ablation randomized to AAD or no AAD for the first 6 weeks, the primary end-point was a composite of (1) atrial arrhythmia ≥24 hours, (2) atrial arrhythmias requiring hospitalization, cardioversion, or initiation or change of AAD, and (3) intolerance of AAD requiring cessation. Fifty-three patients were randomized to AAD and 57 to no AAD. Fewer patients reached the primary end-point in the AAD group than the no-AAD group (19% vs 42%, P = .005). Fewer events occurred in the AAD group (13% vs 28%, P = .05) when end-points of AF ≥24 hours,... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125164 Thu, 10 Dec 2009 00:00:00 +0100 3125164 http://www.medworm.com/index.php?rid=3125163&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012594%2Fabstract%3Frss%3Dyes Levin et al (J Clin Invest 2009;119:3420–3436, PMID 19855129) reported the presence of melanocyte-like cells in the heart. The melanin synthesis enzyme dopachrome tautomerase (DCT) is involved in intracellular calcium and reactive species regulation in melanocytes. The authors characterized a unique DCT-expressing cell population within murine and human hearts that populated the pulmonary veins, atria, and atrioventricular canal. Expression profiling demonstrated that this population expressed adrenergic and muscarinic receptors and displayed transcriptional profiles distinct from dermal melanocytes. Adult mice lacking DCT displayed normal cardiac development but an increased susceptibility to atrial arrhythmias. Cultured primary cardiac melanocyte-like cells were excitable, and those la... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125163 Thu, 10 Dec 2009 00:00:00 +0100 3125163 http://www.medworm.com/index.php?rid=3303844&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013290%2Fabstract%3Frss%3Dyes Conclusion: Earliest recorded postshock activation is in the Purkinje system after LDVF but not after SDVF. This difference raises the possibility that the optimal defibrillation strategy is different for SDVF and LDVF. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303844 Thu, 03 Dec 2009 00:00:00 +0100 3303844 http://www.medworm.com/index.php?rid=3303843&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013356%2Fabstract%3Frss%3Dyes Background: Hypertension is frequently complicated by the development of atrial fibrillation (AF). However, the mechanisms of this link remain poorly understood. In addition, whether short-term hypertension can result in a substrate for AF is not known.Objective: The purpose of this study was to characterize the atrial substrate predisposing to AF due to short-duration hypertension.Methods: Sixteen sheep were studied: 10 had induced hypertension for 7 ± 4 weeks via the “one-kidney, one-clip” model, and six were controls. Cardiac magnetic resonance imaging was used to assess functional changes. Open-chest electrophysiological study was performed using a custom-made 128-electrode epicardial plaque applied to both right (RA) and left atria (LA), including the Bachmann's bundle, to determ... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303843 Thu, 03 Dec 2009 00:00:00 +0100 3303843 http://www.medworm.com/index.php?rid=3303842&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013277%2Fabstract%3Frss%3Dyes Background: The presence of epicardial fat can confound the quantification of scar during transpericardial electroanatomic mapping. The electrogram (EGM) characteristics of epicardial fat have not been systematically compared with infarct scar using gross and histopathological analysis as a gold standard.Objective: The purpose of this study was to compare the EGM characteristics of epicardial fat with infarct scar.Methods: A closed-chest infarction was created in 40–50 kg pigs by occlusion of the circumflex artery for 150 minutes using an angioplasty balloon. This artery was chosen to minimize any potential overlap of epicardial fat with infarct and to spare any septal involvement. After 4–12 weeks of infarct healing, epicardial mapping was performed. EGMs in low-voltage regions ( (Sou... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303842 Thu, 03 Dec 2009 00:00:00 +0100 3303842 http://www.medworm.com/index.php?rid=3303836&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013368%2Fabstract%3Frss%3Dyes Conclusion: KCNE1 S38G SNP is associated with HF predisposition in two study populations. Nevertheless, further studies performed in larger populations and aimed to better define the role of this locus are required. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303836 Thu, 03 Dec 2009 00:00:00 +0100 3303836 http://www.medworm.com/index.php?rid=3303834&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013319%2Fabstract%3Frss%3Dyes Background: Implantable cardioverter-defibrillator (ICD) shocks have been associated with an increased risk of death. It is unknown whether this is due to the ventricular arrhythmia (VA) or shocks and whether antitachycardia pacing (ATP) termination can reduce this risk.Objective: The purpose of this study was to determine whether mortality in ICD patients is influenced by the type of therapy (shocks of ATP) delivered.Methods: Cox models evaluated effects of baseline characteristics, ventricular tachycardia (VT; 250 bpm), and therapy type (shocks or ATP) on mortality among 2135 patients in four trials of ATP to reduce shocks.Results: Over 10.8 ± 3.3 months, 24.3% patients received appropriate shocks (50.6%) or ATP only (49.4%), and 6.6% died. Mortality predictors were age (hazard ratio 1.... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303834 Thu, 03 Dec 2009 00:00:00 +0100 3303834 http://www.medworm.com/index.php?rid=3303831&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013332%2Fabstract%3Frss%3Dyes Conclusion: Even when delivering multiple lesions with 6-mm-tip catheters, Cryo is less effective than RF. RF is recommended as a first-line treatment, although the only major complication occurred in the RF group. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303831 Thu, 03 Dec 2009 00:00:00 +0100 3303831 http://www.medworm.com/index.php?rid=3303829&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013320%2Fabstract%3Frss%3Dyes During the last decade we have witnessed an impressive worldwide race to improve the efficacy and safety of catheter ablation of atrial fibrillation. In spite of many different approaches to tackle the challenges to find a curative treatment for atrial fibrillation, the electrophysiological community has reached some common grounds. One of them is the need to achieve complete pulmonary vein (PV) electrical disconnection in all patients as the only valid endpoint of PV isolation. While it is preferable that entrance and exit block of the PV should be demonstrated, the standard procedure to check PV isolation is entrance block assessment during sinus rhythm or by pacing the left atrium while checking the PVs with a circular mapping catheter for absent or dissociated PV potentials. However, e... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303829 Thu, 03 Dec 2009 00:00:00 +0100 3303829 http://www.medworm.com/index.php?rid=3303824&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013289%2Fabstract%3Frss%3Dyes Background: Termination of persistent atrial fibrillation (AF) by radiofrequency ablation (RFA) is associated with a high probability of freedom from AF but requires extensive ablation and long procedure times.Objective: The purpose of this study was to determine whether a critical decrease in the dominant frequency (DF) of AF is a sufficient endpoint for RFA of persistent AF.Methods: Antral pulmonary vein isolation (APVI) followed by RFA of complex fractionated atrial electrograms (CFAEs) in the atria and coronary sinus was performed in 100 consecutive patients with persistent AF. The DF of AF in lead V1 and in the coronary sinus was determined by fast Fourier transform (FFT) analysis at baseline and before termination of AF to identify a critical decrease in DF predictive of sinus rhythm... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303824 Thu, 03 Dec 2009 00:00:00 +0100 3303824 http://www.medworm.com/index.php?rid=3205810&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013253%2Fabstract%3Frss%3Dyes Since the seminal observation by Haissaguerre and colleagues of common triggers of atrial fibrillation (AF) from the pulmonary veins (PVs), targeting of the PVs has become the cornerstone of most AF ablation strategies. The ablation technique has evolved from focal ablation of PV triggers to complete electrical isolation of the PVs, initially using a segmental approach and now a circumferential approach. Whether ablation is performed at the PV ostium or at the antrum, there is general agreement that complete electrical isolation of the PVs (as demonstrated by entrance-and, if possible, exit-block) should be the endpoint of the basic lesion set for all forms of AF. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205810 Thu, 03 Dec 2009 00:00:00 +0100 3205810 http://www.medworm.com/index.php?rid=3303832&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013058%2Fabstract%3Frss%3Dyes Conclusion: In this swine model of RV dysfunction and in adults with repaired TOF, BiV stimulation significantly improved RV and LV function by alleviating electromechanical dyssynchrony. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303832 Mon, 23 Nov 2009 00:00:00 +0100 3303832 http://www.medworm.com/index.php?rid=3303827&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013034%2Fabstract%3Frss%3Dyes Background: Ventricular arrhythmias are known to originate from the aortic sinus of Valsalva.Objective: The purpose of this study was to identify the characteristics associated with ventricular arrhythmias originating from the right coronary cusp–left coronary cusp (RCC–LCC) commissure.Methods: Thirty-seven consecutive patients with ventricular arrhythmias originating from the aortic cusp region were studied. Intracardiac echocardiography and electroanatomic mapping were used to define coronary cusp anatomy and catheter position. Ventricular arrhythmias from the RCC–LCC commissure were compared with ventricular arrhythmias originating from other sites in the aortic cusp region.Results: Nineteen (51%) ventricular arrhythmias had an anatomic origin at the RCC–LCC commissure. Eighteen... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303827 Thu, 19 Nov 2009 00:00:00 +0100 3303827 http://www.medworm.com/index.php?rid=3205819&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013022%2Fabstract%3Frss%3Dyes There is great interest in developing novel diagnostic approaches that target the prediction of fatal ventricular arrhythmias after myocardial infarction (MI). It is well known that impairment of autonomic function plays important roles in serious ventricular arrhythmias leading to sudden cardiac death in patients with MI. Numerous techniques have been developed to evaluate autonomic function in health and disease. These techniques can be classified into two general categories. Heart rate variability (HRV) and heart rate turbulence (HRT) are typical noninvasive techniques for identifying tonic activity of autonomic function and baroreflex sensitivity (BRS), especially parasympathetic activity, respectively. The term HRT describes short-term fluctuations in sinus cycle length following spon... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205819 Wed, 18 Nov 2009 00:00:00 +0100 3205819 http://www.medworm.com/index.php?rid=3303840&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013009%2Fabstract%3Frss%3Dyes Conclusion: The degree of hyperkalemia in the surviving subepicardium, the lateral width of border zone, and cellular uncoupling between the subepicardium and midmyocardium determine dispersion of refractoriness, conduction velocity, excitability, and, therefore, inducibility of reentry during phase 1B. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303840 Mon, 16 Nov 2009 00:00:00 +0100 3303840 http://www.medworm.com/index.php?rid=3303838&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012727%2Fabstract%3Frss%3Dyes Conclusion: Percutaneous epicardial suture ligation of the LAA is feasible with this novel device. The concomitant use of an endoluminal balloon catheter placed in the LAA significantly increases the likelihood of excluding the entire LAA from the circulation. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303838 Mon, 16 Nov 2009 00:00:00 +0100 3303838 http://www.medworm.com/index.php?rid=3303830&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012995%2Fabstract%3Frss%3Dyes Conclusion: The single-catheter approach using the MESH for mapping and ablation was associated with a high AF recurrence rate within the first year despite a high acute success rate. Thus, the minimalist complexity of the procedure must be balanced with the poor clinical success leading to a high number of second procedures. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303830 Mon, 16 Nov 2009 00:00:00 +0100 3303830 http://www.medworm.com/index.php?rid=3205808&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109013010%2Fabstract%3Frss%3Dyes Atrial fibrillation (AF) ablation is increasingly used for treatment of AF in symptomatic patients. Limited ablation isolating the thoracic veins is effective for paroxysmal AF and normal hearts. Because of limited efficacy with persistent AF, attempts to improve success have involved more extensive ablation. These approaches include linear ablation, ablation of fragmented electrograms during AF, and transmural ablation of the retroatrial cardiac ganglia. Although success rates may have improved with such approaches, inadvertent consequences of such extensive ablation have been acknowledged. Concerns include mechanical dysfunction of the atria despite restoration of sinus rhythm and collateral damage to extracardiac structures. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205808 Mon, 16 Nov 2009 00:00:00 +0100 3205808 http://www.medworm.com/index.php?rid=3303828&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012739%2Fabstract%3Frss%3Dyes Conclusion: Complete loss of pace capture directly along the circumferential ablation line correlates with entrance block in 95% of vein pairs and can be achieved without circular mapping catheter guidance. Thus, pace capture along the ablation line can be used to identify conduction gaps. Interestingly, more RF ablation energy was required to achieve loss of pace capture along the ablation line than for entrance block into PVs. Further study is warranted to determine whether this method results in more durable ablation lesions that reduce recurrence of AF. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303828 Fri, 13 Nov 2009 00:00:00 +0100 3303828 http://www.medworm.com/index.php?rid=3303823&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012740%2Fabstract%3Frss%3Dyes Background: Terminal P-wave inversion in lead V1 representing left atrial overload has been considered a precursor of atrial fibrillation (AF).Objective: The purpose of this study was to determine whether this P-wave morphologic characteristic can predict the development of AF.Methods: Digital analysis of 12-lead ECGs was performed to enroll patients with P terminal force ≥0.06 s × 2 mm in lead V1 from among a database of 308,391 ECG recordings. The prognostic value of ECG characteristics for developing AF was determined.Results: A total of 78 patients (mean age 52 ± 19 years) with left atrial overload were chosen from among 102,065 patients in the database. During mean follow-up of 43 months, 15 (19%) patients developed AF (AF group) versus 63 (81%) patients who did not (non-AF group)... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303823 Fri, 13 Nov 2009 00:00:00 +0100 3303823 http://www.medworm.com/index.php?rid=3303845&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012570%2Fabstract%3Frss%3Dyes This report outlines an approach to catheter ablation in a patient with extracardiac Fontan palliation in which the heart was accessed via the conduit. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303845 Mon, 09 Nov 2009 00:00:00 +0100 3303845 http://www.medworm.com/index.php?rid=3303826&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012685%2Fabstract%3Frss%3Dyes This study sought to report the electrophysiological properties of a series of patients with prior MI who underwent radiofrequency ablation (RFA) for VT originating instead from a focal source.Methods: The electrophysiological properties of 46 patients with prior MI (male 89%, age 64.8 ± 10.2 years) who underwent RFA for sustained VT were studied. A total of 101 VTs were induced (92 [91%] macro–re-entrant VT and 9 [9%] focal VT).Results: One patient had adenosine-sensitive idiopathic focal VT. The focal VT group had a significantly shorter pre-systolic interval (electrogram to QRS) during VT compared with the macro–re-entrant VT group (36 ± 17 ms vs. 117 ± 67 ms, P = .001). The successful ablation sites in the focal VT group also had a significantly lower ratio (in percentage) of el... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3303826 Mon, 09 Nov 2009 00:00:00 +0100 3303826 http://www.medworm.com/index.php?rid=3205818&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012612%2Fabstract%3Frss%3Dyes Background: Autonomic dysfunction tends to improve over time after acute myocardial infarction (MI), but the clinical significance of autonomic remodeling is not well known.Objective: The purpose of this study was to test the hypothesis that the amount of recovery of autonomic function early after MI is associated with a risk for serious arrhythmias.Methods: The prognostic significance of autonomic remodeling after MI was assessed in one post-MI cohort [Cardiac Arrhythmia and Risk Stratification after Myocardial Infarction (CARISMA)] and validated in a second cohort [Risk Estimation After Infarction, Noninvasive Evaluation (REFINE)]. Changes in heart rate variability (ΔHRV) and heart rate turbulence (ΔHRT) were measured from 24-hour ECG recordings performed early (5–21 days) and later ... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205818 Mon, 09 Nov 2009 00:00:00 +0100 3205818 http://www.medworm.com/index.php?rid=3205815&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012624%2Fabstract%3Frss%3Dyes In 1992, Pedro and Josep Brugada first described eight patients with a history of aborted sudden cardiac death due to ventricular fibrillation (VF) and a characteristic ECG pattern, consisting of right bundle branch block and ST-segment elevation in the right precordial leads (V1–V3), as a distinct clinical entity. The presence of right bundle branch block thereafter is considered not to be required for the diagnosis of Brugada syndrome, although mild-to-moderate widening of QRS duration often is observed. Two specific types of ST-segment elevation (coved-type and saddleback) are observed in this syndrome, and the pattern and amplitude of ST-segment elevation often are dynamic. Coved-type ST-segment elevation is more frequently recognized just before and after episodes of VF and is repor... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205815 Mon, 09 Nov 2009 00:00:00 +0100 3205815 http://www.medworm.com/index.php?rid=3205809&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012582%2Fabstract%3Frss%3Dyes Conclusion: Conduction recovery after CB-PVI occurs at a high incidence at inferior sites around ipsilateral PV ostia and the LAA–PV ridge. Modifications of the technique to ensure optimal balloon–tissue contact at predilection sites may improve long-term success rates. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205809 Mon, 09 Nov 2009 00:00:00 +0100 3205809 http://www.medworm.com/index.php?rid=3205807&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012557%2Fabstract%3Frss%3Dyes Conclusion: Electrical isolation of the LAA may occur during ablation of persistent AF and AT even when the ablation site is remote from the LAA. This likely is due to disruption of the Bachmann bundle and its leftward extension, which courses along the anterior left atrium and bifurcates to surround the LAA. Monitoring of LAA conduction during ablation of persistent AF or AT is important in avoiding permanent LAA isolation. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205807 Mon, 09 Nov 2009 00:00:00 +0100 3205807 http://www.medworm.com/index.php?rid=3125154&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012569%2Fabstract%3Frss%3Dyes Cardiac arrhythmias in general, and atrial fibrillation (AF) in particular, are important global health problems. Despite extensive studies, arrhythmia mechanisms remain unclear. The problem is complicated because heart function is affected by a complex integration of numerous biochemical and biophysical processes within and among cardiac cells. Interactions within the sinoatrial (SA) node, the heart's primary pacemaker that initiates and regulates the cardiac rhythm, result in one such critical unsolved complexity. Joung et al have recently applied a method of simultaneous recording of intracellular Ca2+ and membrane potential to approach the riddle of complex/intimate interactions between electrophysiology and intracellular Ca2+signaling within cells comprising the SA node. In this issue... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125154 Mon, 09 Nov 2009 00:00:00 +0100 3125154 http://www.medworm.com/index.php?rid=3205825&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS154752710901220X%2Fabstract%3Frss%3Dyes We report a case of phrenic nerve stimulation with endocardial pacing within the substrate for VT in a patient with severe LV wall thinning in proximity to the left phrenic nerve. We describe the techniques used to define the course of the phrenic in proximity to the endocardium and a strategy deployed for successful substrate-based ablation that avoided phrenic nerve injury. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205825 Mon, 02 Nov 2009 00:00:00 +0100 3205825 http://www.medworm.com/index.php?rid=3205823&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012193%2Fabstract%3Frss%3Dyes In the 19th century, observers of the fascinating phenomenon of fibrillation of the heart, which could be induced by the newfound tool of electrical stimulation, proposed two major hypotheses for its initiation and perpetuation. One hypothesis invoked a chaotic disorganization of propagation involving continuous reentry. This hypothesis was based on grossly observable and measurable tissue properties of excitability, conduction, and refractoriness. The other hypothesis proposed rapidly firing foci, microscopic entities beyond the powers of observation with the tools of the time. Integral to the hypothesis of a disorder of propagation was the assumption of heterogeneity of recovery/refractoriness, an idea that has become an axiom of electrophysiology, abundantly verified and informing the c... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205823 Mon, 02 Nov 2009 00:00:00 +0100 3205823 http://www.medworm.com/index.php?rid=3205821&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012181%2Fabstract%3Frss%3Dyes The article by Hoogendijk et al. in this issue of Heart Rhythm stimulates us to think about alternative hypotheses for the Brugada sign in the electrocardiogram (ECG). Elevation of the ST segment in right precordial leads, either spontaneously or in the presence of a sodium-channel-blocking drug (or certain other drugs), is thought to result from early repolarization or late activation in the right ventricular wall. The effects of relatively increased transient outward current on loss of the action potential dome in the right ventricular epicardial cells have been recognized as a mechanism for J-point elevation and ST-segment elevation. From studies of an explanted myopathic human heart with a loss-of-function sodium channel mutation but no overt Brugada pattern, the report by Hoogendijk e... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205821 Mon, 02 Nov 2009 00:00:00 +0100 3205821 http://www.medworm.com/index.php?rid=3205816&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012211%2Fabstract%3Frss%3Dyes Conclusion: Both atrial vulnerability and structural remodeling are enhanced in high-risk patients with BrS, even in those without AF. These morphological characteristics suggest that BrS is a form of genetic myocardial disease. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205816 Mon, 02 Nov 2009 00:00:00 +0100 3205816 http://www.medworm.com/index.php?rid=3053842&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011540%2Fabstract%3Frss%3Dyes Holmes et al colleagues (Lancet 2009;374:534, PMID 19683639) compared percutaneous closure of the left atrial appendage (LAA) with warfarin for prevention of stroke in patients with atrial fibrillation. Patients with nonvalvular atrial fibrillation were eligible for inclusion in this randomized noninferiority trial if they met one of the following conditions: previous stroke or transient ischemic attack, congestive heart failure, diabetes, hypertension, or age ≥75 years. Seven hundred seven eligible patients were assigned in a 2:1 ratio to percutaneous closure of the LAA and discontinuation of warfarin (intervention; n = 463) or to warfarin treatment (n = 244). Efficacy was assessed by a composite end-point of stroke, cardiovascular death, and systemic embolism. At 1,065 patient-years of... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053842 Mon, 02 Nov 2009 00:00:00 +0100 3053842 http://www.medworm.com/index.php?rid=3053841&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011527%2Fabstract%3Frss%3Dyes Ellis et al (Circulation 2009;120:1029, PMID 19738136) studied tecarfarin (ATI-5923), a novel oral vitamin K antagonist. The authors hypothesized that the time in the therapeutic range for tecarfarin will exceed values usually experienced with warfarin. The authors conducted a 6- to 12-week open-label, multicenter, phase IIA study of 66 atrial fibrillation patients with a mild-to-moderate risk of stroke. Sixty-four subjects (97%) were taking warfarin at enrollment and were switched to tecarfarin. After the initial 3 weeks of tecarfarin treatment, mean interpolated time in the therapeutic range was 71.4%. Median daily dose (for an individual patient) to maintain an international normalized ratio between 2 and 3 was 15.6 mg (range 6–29 mg). The authors conclude that tecarfarin may possess ... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053841 Mon, 02 Nov 2009 00:00:00 +0100 3053841 http://www.medworm.com/index.php?rid=2951823&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010832%2Fabstract%3Frss%3Dyes Despite the efficacy of implantable cardiac devices in elderly patients, a bias against their use seems to persist. A major concern about placing these devices in elderly patients is the complication rate. The incidence of complications in the elderly are not well recorded from the general population and most randomized trials excluded elderly patients. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951823 Sun, 01 Nov 2009 00:00:00 +0100 2951823 http://www.medworm.com/index.php?rid=2951822&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010820%2Fabstract%3Frss%3Dyes Studies have increasingly identified genetics as an important predisposing factor for developing atrial fibrillation (AF). Mutations in NPPA, encoding the circulating hormone atrial natriuretic peptide (ANP) as well as other functional proteins, have recently been implicated in familial AF. The mechanisms underlying AF susceptibility with mutant NPPA however remain uncertain. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951822 Sun, 01 Nov 2009 00:00:00 +0100 2951822 http://www.medworm.com/index.php?rid=2951821&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010819%2Fabstract%3Frss%3Dyes Indications for cardiac resynchronization therapy (CRT) include prolonged QRS duration (typically LBBB), advanced heart failure (HF, NYHA III/IV), and severe left ventricular (LV) dysfunction. The role of CRT in patients with intermittent LBBB associated with acute HF is unknown. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951821 Sun, 01 Nov 2009 00:00:00 +0100 2951821 http://www.medworm.com/index.php?rid=2951820&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010807%2Fabstract%3Frss%3Dyes It is known that elevated at baseline intracardiac repolarization lability increases the risk of life-threatening ventricular tachyarrhythmias (VT/VF) in patients with structural heart disease. We hypothesize that patients with increasing over 6 months period beat-to-beat QT variability experience a greater increase in their probability of having VT/VF than those with decreasing or stable low intracardiac repolarization lability. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951820 Sun, 01 Nov 2009 00:00:00 +0100 2951820 http://www.medworm.com/index.php?rid=2951819&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010790%2Fabstract%3Frss%3Dyes Atrial Fibrillation (AF), the most common sustained arrhythmia in clinical practice. Despite improvement in treatment, most patients suffer from symptoms and recurrences of arrhythmia. Studies on the neurohormonal remodeling in AF have become increasingly important in AF. The aim of this study was to measure plasma biomarkers in patients with AF, before and after electrical cardioversion. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951819 Sun, 01 Nov 2009 00:00:00 +0100 2951819 http://www.medworm.com/index.php?rid=2951818&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010789%2Fabstract%3Frss%3Dyes Open-irrigated radiofrequency catheter ablation (oiRFA) of atrial fibrillation (AF) imposes a volume load and risk of cardiac decompensation. We sought to assess the effect of volume administration during ablation on left atrial (LA) pressure and B-type natriuretic peptide (BNP). (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951818 Sun, 01 Nov 2009 00:00:00 +0100 2951818 http://www.medworm.com/index.php?rid=2951817&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010777%2Fabstract%3Frss%3Dyes In the long-QT syndrome (LQTS), genetic factors other than the primary mutation may modify the probability of life-threatening events. Genome-wide association studies did show that polymorphisms in NOS1AP, a regulator of neuronal nitric oxide synthase, are associated not only with baseline QT interval but also with the risk of SCD in white adults. We tested the hypothesis that common variants in NOS1AP might modify the risk of clinical manifestations and the degree of QT interval prolongation in a South African LQTS population segregating a founder mutation in KCNQ1 (A341V), and thus having an identical arrhythmogenic substrate. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951817 Sun, 01 Nov 2009 00:00:00 +0100 2951817 http://www.medworm.com/index.php?rid=2951816&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010765%2Fabstract%3Frss%3Dyes Control of recurrent ventricular tachycardia (VT) is an important determinant of quality of life in patients with implantable defibrillators. The role of invasive catheter ablation for this purpose in elderly patients with ischemic heart disease has not been defined. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951816 Sun, 01 Nov 2009 00:00:00 +0100 2951816 http://www.medworm.com/index.php?rid=2951815&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010741%2Fabstract%3Frss%3Dyes Activation of calcium/calmodulin-dependent protein kinase II (CaMKII) has been linked to arrhythmias and heart failure. Through calcineurin, CaMKII has also been implicated in inducing electrical remodeling. Enhanced susceptibility to arrhythmias based on electrical remodeling is also present in the chronic AV block (CAVB) dog, although in the setting of physiologic hypertrophy. Because the stimuli involved (increased angiotensin II, norepinephrine, and intracellular calcium) are known CaMKII activators, this study addressed the involvement of the CaMKII-calcineurin pathway at different time points (0, 2, and 9 weeks) in the remodeling process of the CAVB dog. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951815 Sun, 01 Nov 2009 00:00:00 +0100 2951815 http://www.medworm.com/index.php?rid=2951814&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS154752710901073X%2Fabstract%3Frss%3Dyes Ventricular fibrillation (VF) is the most lethal cardiac arrhythmia, yet the underlying mechanisms are poorly understood. VF occurs most commonly in the presence of markedly increased tissue fibrosis, as seen in aging or heart disease. We hypothesize that electrotonic coupling of ventricular myocytes to fibroblasts under stress can augment stress effects to impair myocyte repolarization reserve and promote the emergence of known VF triggers such as early afterdepolarizations (EADs) and triggered activity. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951814 Sun, 01 Nov 2009 00:00:00 +0100 2951814 http://www.medworm.com/index.php?rid=2951813&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010728%2Fabstract%3Frss%3Dyes Through genetic studies in multiple linked families, we previously identified dipeptidyl-aminopeptidase-like protein 6 (DPP6) as a gene for idiopathic ventricular fibrillation and proposed increased expression of this gene as a likely pathogenic mechanism in this disorder. Co-expression studies in heterologous expression systems point to DPP6 as a putative β-subunit of human cardiac Kv4.3 transient outward current, but the function of DPP6 in native cardiac myocytes is unknown. Here we studied the effects of DPP6 overexpression on action potential and transient outward current characteristics in adult ventricular myocytes. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951813 Sun, 01 Nov 2009 00:00:00 +0100 2951813 http://www.medworm.com/index.php?rid=2951812&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010716%2Fabstract%3Frss%3Dyes Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC) is an inherited disease characterized by replacement of healthy myocardium with fibrous and fatty tissue, cardiac arrhythmias, and sudden death. ARVC has been associated with mutations in desmosomal proteins, most prominently in the gene coding for plakophilin-2 (PKP2). How disruption of desmosomal proteins in cardiac myocytes leads to the disproportionate extent of fibrosis, and fat accumulation, observed in ARVC-afflicted hearts is unclear. Here, we propose that fibrofatty infiltration has its origins (at least in part) in nonmyocyte cardiac cells. Our attention centers on the epithelial cells that conform the cardiac epicardium and act as progenitors of the cardiac fibroblast lineage. We speculate that desmosomal integrity... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951812 Sun, 01 Nov 2009 00:00:00 +0100 2951812 http://www.medworm.com/index.php?rid=2951811&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010704%2Fabstract%3Frss%3Dyes Developing strategies that selectively target the atrium are of great clinical interest to avoid ventricular arrhythmias during treatment of atrial fibrillation (AF). Our goal was to exploit inherent differences between the atrium and the ventricle in terminating acute AF. We targeted differences in (1) ion channel makeup, i.e., the presence of an atrial-specific ion channel, the ultrarapid delayed rectifier K+ current (IKur), and (2) biophysical properties, i.e., the more negative steady-state half-inactivation membrane voltage value for the Na+ current (INa) in the atrium. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951811 Sun, 01 Nov 2009 00:00:00 +0100 2951811 http://www.medworm.com/index.php?rid=2951810&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010698%2Fabstract%3Frss%3Dyes Electrical impulses in the heart propagate via the coordinated action of membrane ion channels and gap junctions. We demonstrate for the first time an approach to convert unexcitable cells into autonomous, electrically excitable and conductive living tissue. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951810 Sun, 01 Nov 2009 00:00:00 +0100 2951810 http://www.medworm.com/index.php?rid=2951809&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010686%2Fabstract%3Frss%3Dyes In this study, we compared the expression and function of IK1 and IK,ACh in right atrium (RA) and LA from patients with sinus rhythm (SR), pAF, and chronic AF (cAF). (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951809 Sun, 01 Nov 2009 00:00:00 +0100 2951809 http://www.medworm.com/index.php?rid=2951808&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010674%2Fabstract%3Frss%3Dyes In this study, we explored the effects of hypoxia on action potential (AP) morphology in the presence or absence of β-adrenergic stimulation. We sought to determine whether there are conditions that lead to arrhythmic disturbances in the form of greatly prolonged AP duration (APD), early afterdepolarizations (EADs) and/or triggered activity (TA). (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951808 Sun, 01 Nov 2009 00:00:00 +0100 2951808 http://www.medworm.com/index.php?rid=2951807&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010662%2Fabstract%3Frss%3Dyes Impaired excitation-contraction coupling manifested in dystrophic cardiomyopathy is attributed to aberrant intracellular Ca2+ regulation. Increased phosphorylation of serine 2808 (S2808) of ryanodine receptors (RyR2) has been implicated in augmented sarcoplasmic reticulum (SR) Ca2+ release and cardiac dysfunction. The aim of this study was to assess whether inhibition of protein kinase A (PKA) phosphorylation of RyR2 may prevent dystrophic cardiomyopathy in mice by improving excitation-contraction coupling functions. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951807 Sun, 01 Nov 2009 00:00:00 +0100 2951807 http://www.medworm.com/index.php?rid=2951806&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010650%2Fabstract%3Frss%3Dyes Right precordial ST elevation after sodium channel blockade has been associated with right ventricular structural discontinuities and sudden cardiac death. The mechanism of ST elevation is debated. We hypothesized that sodium channel blockade causes ST elevation by current-to-load mismatch and excitation failure in structurally discontinuous myocardium. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951806 Sun, 01 Nov 2009 00:00:00 +0100 2951806 http://www.medworm.com/index.php?rid=2951805&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010649%2Fabstract%3Frss%3Dyes A mutant glycerol-3-phosphate dehydrogenase 1-like A280V (A280V GPD1-L) reduces cardiac Na+ current (INa) and causes Brugada syndrome. Recent data suggest that this effect is dependent on alterations in nicotinamide adenine dinucleotide (NADH), reactive oxygen species (ROS), and protein kinase C (PKC) activation. Because NADH and PKC can activate ROS production from mitochondria, we investigated the role of this organelle in mediating the effects of mutant GPD1-L and NADH on INa. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951805 Sun, 01 Nov 2009 00:00:00 +0100 2951805 http://www.medworm.com/index.php?rid=2951804&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010637%2Fabstract%3Frss%3Dyes Chronic kidney disease (CKD) may contribute to left ventricular hypertrophy, fibrosis, diastolic dysfunction, and impaired coronary flow reserve, which ultimately lead to an increased risk for adverse cardiovascular events. We hypothesized that cardiovascular remodeling is a continuous process starting from the early stage of CKD and sought to explore the cellular electrophysiologic changes in left ventricular myocytes after single nephrectomy (SNx) in rats. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951804 Sun, 01 Nov 2009 00:00:00 +0100 2951804 http://www.medworm.com/index.php?rid=2951803&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010625%2Fabstract%3Frss%3Dyes Antiarrhythmic peptide (AAP) analogues are promising new antiarrhythmic drugs that target the gap junction protein connexin43 (Cx43). Their exact molecular effect is still unknown. Previous data show that one analogue prevents phosphorylation on one (serine 297 [S297]) of three new phosphorylation sites on Cx43 (S296, S297, S306) during myocardial ischemia. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951803 Sun, 01 Nov 2009 00:00:00 +0100 2951803 http://www.medworm.com/index.php?rid=2951802&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010613%2Fabstract%3Frss%3Dyes In primary cultures of neonatal rat ventricular myocytes, exogenous vascular endothelial growth factor (VEGF) has been shown to rapidly increase the amount of connexin43 (Cx43), the major ventricular electrical coupling protein in gap junctions. This has led to the interesting hypothesis that VEGF, generally thought to regulate angiogenesis, may also regulate cardiac conduction by modulating expression of Cx43. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951802 Sun, 01 Nov 2009 00:00:00 +0100 2951802 http://www.medworm.com/index.php?rid=2951801&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010601%2Fabstract%3Frss%3Dyes Congestive heart failure with preserved ejection fraction (diastolic dysfunction) is an increasingly prevalent health burden and has no approved therapeutic options. We previously demonstrated that a deoxycorticosterone acetate (DOCA)-salt mouse model produces cardiac oxidative stress and diastolic dysfunction with preserved systolic function. Oxidative stress modulates inward sodium current (INa) by increasing late INa, reducing net cytosolic Ca2+ efflux, and impairing myocyte relaxation. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951801 Sun, 01 Nov 2009 00:00:00 +0100 2951801 http://www.medworm.com/index.php?rid=2951800&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010595%2Fabstract%3Frss%3Dyes The right ventricular subepicardium is the primary location of fibrofatty replacement in arrhythmogenic right ventricular cardiomyopathy and is thought to be the source of right precordial ST-segment elevation in Brugada syndrome. Although structural heart disease is an exclusion criterion for Brugada syndrome, clinically undetectable structural abnormalities have been suggested to play a role in a subset of Brugada patients. Fractionation of local electrograms is then expected but has only rarely been observed in endocardial mapping studies of Brugada patients. We hypothesized that structural changes limited to subepicardial tissue, in combination with sodium channel inhibition, can cause ST-segment changes in right precordial ECG leads and fractionation in epicardial electrograms but not... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951800 Sun, 01 Nov 2009 00:00:00 +0100 2951800 http://www.medworm.com/index.php?rid=2951799&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010583%2Fabstract%3Frss%3Dyes In this study, we investigated the phenotype of lentivirally delivered TBX3 in myocytes and the usefulness of TBX3 gene transfer in biopacemaker engineering. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951799 Sun, 01 Nov 2009 00:00:00 +0100 2951799 http://www.medworm.com/index.php?rid=2951798&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010571%2Fabstract%3Frss%3Dyes This study aimed to develop a pipeline that uses in vivo patient images to estimate fiber orientations for heart simulations. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951798 Sun, 01 Nov 2009 00:00:00 +0100 2951798 http://www.medworm.com/index.php?rid=2951797&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS154752710901056X%2Fabstract%3Frss%3Dyes Both canine and human sinoatrial nodes (SANs) are functionally connected to the surrounding atrium by several discrete sinoatrial exit pathways (SEPs). These SEPs not only are important in maintaining pacemaking function but also participate in atrial reentrant arrhythmias such as atrial flutter (AFl) and atrial fibrillation (AF). (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951797 Sun, 01 Nov 2009 00:00:00 +0100 2951797 http://www.medworm.com/index.php?rid=2951796&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010558%2Fabstract%3Frss%3Dyes As pediatric cardiac surgery is increasingly performed in the first year of life, the need for understanding calcium regulation in this age group is becoming more important. Thus, we examined the effect of sympathetic stimulation on contractility and calcium current (ICa) in ventricular biopsies from hypoplastic left heart syndrome (HLHS, age (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951796 Sun, 01 Nov 2009 00:00:00 +0100 2951796 http://www.medworm.com/index.php?rid=2951795&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010546%2Fabstract%3Frss%3Dyes The three-dimensional (3-D) distribution of electromechanical delay (EMD), the time interval between onset of myofiber shortening and that of electrical activation, has not been characterized in the failing heart. The aim of this study was to quantify this EMD distribution during left bundle branch block (LBBB) and biventricular pacing (BiV). We hypothesized that heterogeneity in EMD distribution arises from myofiber prestretch in the different regions of the failing heart and depends on the electrical activation sequence. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951795 Sun, 01 Nov 2009 00:00:00 +0100 2951795 http://www.medworm.com/index.php?rid=2951794&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010534%2Fabstract%3Frss%3Dyes Implantable cardioverter-defibrillator (ICD) therapy for atrial fibrillation (AF) and flutter (AFl) currently is limited by pain induced by defibrillation shocks. Antitachycardia pacing (ATP) is a painless therapy but is not 100% effective in terminating AF/AFl. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951794 Sun, 01 Nov 2009 00:00:00 +0100 2951794 http://www.medworm.com/index.php?rid=2951793&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010522%2Fabstract%3Frss%3Dyes Intrinsic cardiac ganglionated plexuses are known to play important roles in cardiac arrhythmogenesis. We sought to directly record intrinsic cardiac nerve activity (ICNA) and extrinsic cardiac nerve activity (ECNA) simultaneously and to test the hypothesis that ICNA always precedes the onset of spontaneous atrial tachyarrhythmia. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951793 Sun, 01 Nov 2009 00:00:00 +0100 2951793 http://www.medworm.com/index.php?rid=2951792&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010510%2Fabstract%3Frss%3Dyes Mutations in SCN5A may be associated with the development of myocardial structural abnormalities with increasing age, likely caused by intracellular sodium ([Na+]i) and calcium ([Ca2+]i) dysregulation secondary to increased sodium influx due to enhanced late sodium current (INa,late). We previously showed that Scn5a-1798insD+/- transgenic mice of two distinct inbred strains display variable conduction disease severity. Here, we hypothesized that genetic background determines magnitude of INa,late, extent of [Na+]i and [Ca2+]i dysregulation, and severity of cardiomyopathy in this mouse model. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951792 Sun, 01 Nov 2009 00:00:00 +0100 2951792 http://www.medworm.com/index.php?rid=2951791&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010509%2Fabstract%3Frss%3Dyes Ventricular repolarization is promoted by delayed rectifier potassium currents. Mutations in the genes underlying these currents, primarily IKr, IKs, and IK1, have been found to cause congenital long QT syndrome (LQTS), which is an inherited disorder leading to sudden cardiac death from fatal cardiac arrhythmias. Kir3.1/3.4 channels have been ascribed a prominent role in atrial and nodal parasympathetic regulation, where acetylcholine-mediated muscarinic stimulation leads to activation of this channel complex, thereby generating G-protein-coupled inward rectifier potassium channel current (IK,ACh). However, a functional role of these channels in ventricle has not been demonstrated in humans. Recent evidence indicates that in conventional whole-cell recordings, IK,Ach in ventricular myocyte... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951791 Sun, 01 Nov 2009 00:00:00 +0100 2951791 http://www.medworm.com/index.php?rid=2951790&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010492%2Fabstract%3Frss%3Dyes Cellular, tissue, and clinical studies link action potential (AP) alternans to ventricular tachycardia (VT) and fibrillation (VF). We recently that alternans in AP voltage (APV-ALT) can predict VT/VF in patients with heart failure (HF) and that APV-ALT implicate reduced calcium uptake (Iup) into the sarcoplasmic reticulum. However, the rate-dependent mechanisms for APV-ALT in failing versus nonfailing human myocardium are poorly understood. Using a combined clinical and modeling approach, we sought to test the hypothesis that reduced Iup leads to unique rate-dependent APV-ALT that distinguish patients en route to VT/VF from controls. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951790 Sun, 01 Nov 2009 00:00:00 +0100 2951790 http://www.medworm.com/index.php?rid=2951789&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010480%2Fabstract%3Frss%3Dyes We examined the electrophysiologic effects of the combined ion channel blocker AZD1305 in the right atrium (RA) and ventricle in anesthetized dogs in vivo (n = 8) and in the dog arterially perfused RA and left ventricular wedge preparation in vitro (n = 5-9). Action potentials (APs) and a pseudo-ECG were recorded in vitro and monophasic AP and surface ECG in vivo. AZD1305 did not change heart rate or blood pressure in vivo but prolonged AP duration (APD90) and increased effective refractory period (ERP) and diastolic threshold of excitation (DTE) predominantly in atria both in vitro and in vivo. Furthermore, in vitro AZD1305 decreased maximum rate of rise of the AP upstroke (Vmax) predominantly in atria. The percent changes in APD90, ERP, DTE, and Vmax induced by 3 μM AZD1305 in vitro and... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951789 Sun, 01 Nov 2009 00:00:00 +0100 2951789 http://www.medworm.com/index.php?rid=3205805&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012120%2Fabstract%3Frss%3Dyes There are a bewildering number of techniques and strategies involved in contemporary catheter ablation for atrial fibrillation (AF), so many that they often defy comparison. Despite this, the Pace and Ablate study by Eitel et al, in the present issue of Heart Rhythm, offers a clever new technique and perhaps an insight into our more general progress in this field. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205805 Fri, 30 Oct 2009 00:00:00 +0100 3205805 http://www.medworm.com/index.php?rid=3205827&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012053%2Fabstract%3Frss%3Dyes What is the origin of normal cardiac pacemaking is an obviously intriguing question, given the fundamental role of pacemaker activity in cardiac function. According to early studies based on experiments in Purkinje fibers, pacemaking was first attributed to the decay of an outward current during diastolic depolarization. The process leading to generation of diastolic depolarization, hence pacemaker activity, was then re-evaluated in the late 1970s with the discovery of the “pacemaker” (“funny”, If) current, which introduced a novel concept of pacemaker generated by activation during diastole of a hyperpolarization-gated inward current. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205827 Wed, 28 Oct 2009 00:00:00 +0100 3205827 http://www.medworm.com/index.php?rid=3205813&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109012041%2Fabstract%3Frss%3Dyes Ion channels are multisubunit transmembrane protein complexes that are central to biology electricity, being involved in functions as diverse as cognition, secretion, and the genesis of the heartbeat. The list of mutations in channel subunits that underlie rare heritable arrhythmic syndromes increases on what seems to be a daily basis. These heritable arrhythmias are fascinating experiments of nature that often prompt bedside-to-bench studies that have provided important insights into ion channel structure, subunit composition and function, as well as cardiac electrophysiology. Such is the case reported by Wu et al, who found a mutation (I57T) in KCNE2 (encoding MiRP-1) in unrelated patients with Brugada syndrome (BrS). Mutations in this position (I57T and M57T) previously have been found ... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205813 Wed, 28 Oct 2009 00:00:00 +0100 3205813 http://www.medworm.com/index.php?rid=3125143&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS154752710901203X%2Fabstract%3Frss%3Dyes Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary disease of heart muscle associated with serious arrhythmias and/or sudden death that may occur early in the disease before significant structural remodeling and contractile dysfunction develop. It typically affects the right ventricular free wall, although left dominant and biventricular forms are being recognized increasingly. The characteristic pathological features are degeneration of cardiac myocytes and replacement by fat and fibrous tissue, but the extent of this change can be quite variable and it is not necessarily conspicuous in patients who die suddenly. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125143 Wed, 28 Oct 2009 00:00:00 +0100 3125143 http://www.medworm.com/index.php?rid=3205817&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011850%2Fabstract%3Frss%3Dyes Conclusion: The relationship between atrial and ventricular CL is useful in differentiating AT from VT with retrograde conduction. A change in atrial CL that predicts the change in subsequent ventricular CL rules in AT and excludes VT. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205817 Mon, 26 Oct 2009 00:00:00 +0100 3205817 http://www.medworm.com/index.php?rid=3205806&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011898%2Fabstract%3Frss%3Dyes Background: Most atrial fibrillation (AF) ablation studies have consisted predominantly of males; accordingly, there is a paucity of information on the safety and efficacy of catheter ablation in a large cohort of female AF patients.Objective: The purpose of this study was to evaluate catheter ablation for AF in female patients.Methods: From January 2005 to May 2008, 3265 females underwent pulmonary vein antrum isolation. Success rates, patient profiles, and complications were collected.Results: Approximately 16% of our population was female (P (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205806 Mon, 26 Oct 2009 00:00:00 +0100 3205806 http://www.medworm.com/index.php?rid=3205803&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011916%2Fabstract%3Frss%3Dyes Inflammation has been implicated in the etiopathogenesis of several cardiovascular conditions. The strongest causal relationship thus far has been demonstrated in the setting of coronary and peripheral vascular disease, where studies have shown a significant association between markers of inflammation and the initiation/progression of atherosclerosis. More recently, inflammatory biomarkers such as interleukin 6 (IL-6) and C-reactive proteins (CRP) have also been found to be elevated in the setting of atrial fibrillation (AF). This was first demonstrated by Bruin et al in patients undergoing coronary artery by pass surgery in whom peak CRP elevations corresponded closely with development of post-operative AF. Subsequent studies also have found such an association in the general AF populatio... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205803 Mon, 26 Oct 2009 00:00:00 +0100 3205803 http://www.medworm.com/index.php?rid=3053846&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011874%2Fabstract%3Frss%3Dyes We thank Konstantino et al for their interesting comment on the unusual case of narrow-complex tachycardia with cycle length alternans published in the August 2009 issue of Heart Rhythm. Multiple AV nodal pathways were suspected but could not be demonstrated during electrophysiologic study, and AV reentrant tachycardia was excluded. During electrophysiologic study, slow–fast AV nodal reentrant tachycardia was easily and repetitively inducible, without any cycle length alternans, and the surface ECG was identical to that of the initial tachycardia observed in the emergency room. During the initial tachycardia without cycle length alternans, the morphology of the T wave was constant, without any alternating pattern, whereas during the narrow-complex tachycardia with cycle length alternans ... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053846 Mon, 26 Oct 2009 00:00:00 +0100 3053846 http://www.medworm.com/index.php?rid=3053845&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011862%2Fabstract%3Frss%3Dyes We have read with great interest the manuscript “Narrow-complex tachycardia with cycle length alternans: What is the mechanism?” by Zimmermann M. et al. The authors describe an unusual case of narrow-complex tachycardia with cycle length alternans of 480 ms and 420 ms. The authors state that a closer inspection of the 12 leads electrogram, reveals P wave with 1:2 ratio to the QRS complexes, suggestive of a sinus rhythm with dual atrioventricular (AV) physiology, and 1:2 conduction to the ventricle. In support of this mechanism, an intra cardiac electrogram demonstrating a double response with single atrial echo beat is shown. No evidence of one to two tachycardia is given. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053845 Mon, 26 Oct 2009 00:00:00 +0100 3053845 http://www.medworm.com/index.php?rid=3205822&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011813%2Fabstract%3Frss%3Dyes Conclusions: The IKr agonist recapitulates the electrophysiologic and arrhythmic manifestations of SQT1. Abbreviation of APD and ERP and amplification of SDR predispose to the development of AF by creating the substrate for reentry. Quinidine, but not E-4031 or lidocaine, was effective in preventing AF in this setting. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205822 Mon, 19 Oct 2009 00:00:00 +0100 3205822 http://www.medworm.com/index.php?rid=3125156&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011825%2Fabstract%3Frss%3Dyes If you drove to work on a toll road today, you may have paid the fee automatically without stopping, using a device attached to your windshield. Radiofrequency identification devices (RFIDs) are increasingly being used to track inventory, provide security, and prevent theft. Hospitals also use these systems to control inventory, track expensive medical devices, locate employees to optimize staffing, and calculate patient wait times in emergency rooms. These tags are small enough to implant in a surgical sponge to assure that none are left in an operating room patient. The systems are composed of two parts: a tag attached to the item of interest and a reader that collects information from the tag. Active systems contain a battery that is the source of energy for the tag's antenna and circui... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125156 Mon, 19 Oct 2009 00:00:00 +0100 3125156 http://www.medworm.com/index.php?rid=3125146&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011837%2Fabstract%3Frss%3Dyes A molecular genetic diagnosis in Brugada syndrome (BrS) can facilitate effective family screening for a condition in which death is potentially preventable. Yet, for the asymptomatic individual, a molecular genetic diagnosis of BrS brings a considerable psychological and social burden, as well as interaction with a medical community that is uncertain of best management. We must, therefore, be as sure as we can that a genetic change found in any given individual truly underlies his/her condition. Most such changes identified to date in the SCN5A gene, and other rarer genes linked to BrS, have largely been unique to each family, with limited supporting in vitro evidence of their effect on the cardiac sodium channel. Since genetic variants appear in healthy controls, there is a risk that a ra... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125146 Mon, 19 Oct 2009 00:00:00 +0100 3125146 http://www.medworm.com/index.php?rid=3125145&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011801%2Fabstract%3Frss%3Dyes The initial reports of the Brugada syndrome emphasized the unusual ECG phenotype, the structurally normal heart, the high propensity to sudden death due to ventricular fibrillation, and the fact that the phenotype appeared in multiple family members. One feature recognized early on was provocation of the distinctive ECG phenotype by challenge with sodium channel-blocking drugs. This finding naturally led to the idea that abnormal function of the cardiac sodium channel gene, encoded by SCN5A, might cause the disease. That hypothesis received its initial validation in 1998, with the report of SCN5A mutations, each leading to predicted decreased sodium current, in individuals affected with the Brugada syndrome. The field has come a long way since these initial exciting discoveries, and, as us... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125145 Mon, 19 Oct 2009 00:00:00 +0100 3125145 http://www.medworm.com/index.php?rid=3053825&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011795%2Fabstract%3Frss%3Dyes With the introduction of electroanatomic mapping systems, electrical voltage maps of the chamber of interest and activation maps of arrhythmias have emerged as invaluable tools for successful ablation of focal and reentrant arrhythmias. In reentrant rhythms that cause hemodynamic instability, substrate modification has been demonstrated to achieve meaningful results. In arrhythmias where a scar serves as the substrate for reentry, activation maps and voltage maps must be acquired and displayed separately. During isochronal activation mapping, a fiduciary activation point is chosen, and all mapped points are represented in relation to this reference. The inherent limitation in such mapping is assignment bias, where the subjective selection of an individual local potential within a multicomp... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053825 Mon, 19 Oct 2009 00:00:00 +0100 3053825 http://www.medworm.com/index.php?rid=3205811&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011783%2Fabstract%3Frss%3Dyes Background: Nontransvenous (NTV) implantable cardioverter-defibrillator (ICD) systems with pericardial and/or subcutaneous coils are used in select pediatric and congenital heart disease patients who are not candidates for transvenous ICD leads. Outcomes with these hybrid configurations are not well understood.Objective: The purpose of this study was to compare survival of NTV ICD systems to standard transvenous (TV) ICD systems.Methods: We conducted a retrospective single-center study in which the TV group was matched to the NTV group 2:1 by type of cardiac disease and implant date.Results: There were 39 patients in the NTV group and 78 matched in the TV group. Compared to the TV group, the NTV group was younger (median 7 vs 20 years) with a smaller body surface area at implant (0.9 vs 1.... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205811 Fri, 16 Oct 2009 00:00:00 +0100 3205811 http://www.medworm.com/index.php?rid=2951825&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011552%2Fabstract%3Frss%3Dyes In the article titled, “National ICD Registry Annual Report 2008: Review of the ICD Registry's Third Year, Expansion to include Lead Data and Pediatric ICD Procedures, and Role for Measuring Performance,” which appears in the September 2009 edition of the Journal (2009;6:1397-1401), the name of Charles Berul, MD was inadvertently omitted. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951825 Tue, 13 Oct 2009 00:00:00 +0100 2951825 http://www.medworm.com/index.php?rid=3205820&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011515%2Fabstract%3Frss%3Dyes Conclusion: Right ventricular excitation failure and activation delay by current-to-load mismatch in the subepicardium can cause the Brugada sign. Therefore, current-to-load mismatch may underlie the ventricular arrhythmias in patients with the Brugada sign. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205820 Mon, 12 Oct 2009 00:00:00 +0100 3205820 http://www.medworm.com/index.php?rid=3205814&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011497%2Fabstract%3Frss%3Dyes Conclusion: Bipolar leads V2–4 and V2–5 are more sensitive than lead V2 for detection of the type 1 Brugada pattern. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205814 Mon, 12 Oct 2009 00:00:00 +0100 3205814 http://www.medworm.com/index.php?rid=3205812&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011564%2Fabstract%3Frss%3Dyes Conclusion: The study results suggest that KCNE2 plays a critical role in the normal function of the native Ito channel complex in human heart and that M54T and I57T variants lead to a gain of function of Ito, which may contribute to generating potential arrhythmogeneity and pathogenesis for inherited fatal rhythm disorders. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205812 Mon, 12 Oct 2009 00:00:00 +0100 3205812 http://www.medworm.com/index.php?rid=3205804&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011473%2Fabstract%3Frss%3Dyes Conclusion: Pacing and ablation from the tip of the mapping/ablation catheter is feasible to detect and close gaps within long atrial ablation lines to consistently achieve bidirectional conduction block. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205804 Mon, 12 Oct 2009 00:00:00 +0100 3205804 http://www.medworm.com/index.php?rid=3205802&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011485%2Fabstract%3Frss%3Dyes Conclusion: AF at the time of the blood draw, rather than a history of AF, was independently associated with inflammation. Differences in transcardiac gradients suggest that AF results in sequestration of inflammatory cytokines in the heart. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205802 Mon, 12 Oct 2009 00:00:00 +0100 3205802 http://www.medworm.com/index.php?rid=3125155&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011461%2Fabstract%3Frss%3Dyes Conclusion: Although there is in vitro testing evidence for concern for implantable pacemaker and ICD EMI at LF and HF, the FDA has not received any incident reports of pacemaker or ICD EMI caused by any RFID system. We do not believe the current situation reveals an urgent public health risk. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125155 Mon, 12 Oct 2009 00:00:00 +0100 3125155 http://www.medworm.com/index.php?rid=3125150&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011436%2Fabstract%3Frss%3Dyes I never think of the future—it comes soon enough.Albert Einstein In industrialized nations, one fifth of deaths will occur suddenly and unexpectedly. High-profile trials of primary prevention of sudden death have focused mostly on the patients with established cardiomyopathy, particularly those with previous myocardial infarctions. Unfortunately, the high-risk patients currently targeted for implantation of implantable cardioverter-defibrillators (ICDs) represent only about 10% of the victims of sudden death. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125150 Mon, 12 Oct 2009 00:00:00 +0100 3125150 http://www.medworm.com/index.php?rid=3125142&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS154752710901145X%2Fabstract%3Frss%3Dyes Conclusion: Occurrence of compound and double heterozygotes in ARVC/D index cases is particularly relevant to mutation screening strategy and to genetic counseling. Even if multiple-mutation carriers show a wide variability in clinical expression, the extent of the disease is higher compared to that in single-mutation carriers. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125142 Mon, 12 Oct 2009 00:00:00 +0100 3125142 http://www.medworm.com/index.php?rid=3053844&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011539%2Fabstract%3Frss%3Dyes Dr. Madias has been a longstanding proponent of indexing T-wave alternans (TWA) magnitude to T-wave amplitude, and we thank him for his insightful comments. We evaluated the body surface distribution of TWA by simulating action potential duration (APD) alternans in a 257-node heart model and measuring TWA from body surface potentials at 300 points on the human torso generated via a forward solution. We validated the results of the simulation in 22 patients with left ventricular dysfunction using 112-electrode body surface potential mapping. This provided a unique opportunity to study the relationship between TWA magnitude and T-wave amplitude across the human torso. Indeed, we observed a significant linear relationship between TWA magnitude and T-wave amplitude in both the simulation and t... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053844 Mon, 12 Oct 2009 00:00:00 +0100 3053844 http://www.medworm.com/index.php?rid=3053843&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011503%2Fabstract%3Frss%3Dyes It has been theorized that the magnitude of T-wave alternans (TWA) may be T-wave amplitude dependent, and that “adjustment” or “indexing” of the measured values of TWA for the amplitude (or other attributes) of the T wave (or the entire J-T interval) may be in order. This notion intuitively derives from the fact that ambulatory ECG recordings, serial standard ECGs, and stress test ECGs reveal enormous changes in the amplitude, morphology, and polarity of the T waves in often completely stable patients and normal subjects. Such changes in the T-wave amplitudes must have some influence on TWA, at least on its magnitude. A number of recent studies have provided confirmation of this assertion. A prime example is the contribution by Selvaraj et al in the August 2009 issue of Heart Rhyth... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053843 Mon, 12 Oct 2009 00:00:00 +0100 3053843 http://www.medworm.com/index.php?rid=3053821&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011448%2Fabstract%3Frss%3Dyes Implantable cardioverter-defibrillators (ICDs) rely on high-rate primary cells to power their electronic circuits. These are complex high-energy-density batteries that manufacturers have used since Honeywell (Minneapolis, MN) built the first lithium battery for the AID and AICD defibrillator models in the early 1980s. ICD batteries differ from milliampere-level (up to 300 mA) pacemaker batteries because ICDs need ampere-level pulse currents to deliver high-voltage therapy. Although most ICD batteries have a lithium anode and silver vanadium oxide cathode (LiSVO), new cathode materials are being developed and introduced into clinical use. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053821 Mon, 12 Oct 2009 00:00:00 +0100 3053821 http://www.medworm.com/index.php?rid=3125157&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011412%2Fabstract%3Frss%3Dyes Conclusion: Spontaneous SR Ca release underlies ISO-induced increase of superior SAN activity. As compared with SAN, the AEP is less dependent on the Ca clock and more dependent on the membrane clock for its automaticity. AEPs outside the SAN can effectively serve as backup pacemakers when the Ca clock functionality is reduced. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125157 Fri, 09 Oct 2009 00:00:00 +0100 3125157 http://www.medworm.com/index.php?rid=3125144&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011424%2Fabstract%3Frss%3Dyes This study sought to perform a retrospective analysis of BrS databases from 9 centers that have each genotyped >100 unrelated cases of suspected BrS.Methods: Mutational analysis of all 27 translated exons in SCN5A was performed. Mutation frequency, type, and localization were compared among cases and 1,300 ostensibly healthy volunteers including 649 white subjects and 651 nonwhite subjects (blacks, Asians, Hispanics, and others) that were genotyped previously.Results: A total of 2,111 unrelated patients (78% male, mean age 39 ± 15 years) were referred for BrS genetic testing. Rare mutations/variants were more common among BrS cases than control subjects (438/2,111, 21% vs. 11/649, 1.7% white subjects and 31/651, 4.8% nonwhite subjects, respectively, P (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125144 Fri, 09 Oct 2009 00:00:00 +0100 3125144 http://www.medworm.com/index.php?rid=3125141&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011345%2Fabstract%3Frss%3Dyes Background: Biventricular pacing (BiV) to effect cardiac resynchronization therapy can be technically difficult and fails to elicit a clinical response in 30% to 40% of patients. Direct His-bundle pacing (DHBP) theoretically could obviate some of these problems. Although DHBP is capable of narrowing the QRS in some patients, the consistency with which this can be achieved has not been characterized.Objective: The purpose of this study was to restore His-Purkinje functionality in consecutive patients undergoing de novo clinically mandated cardiac resynchronization therapy.Methods: DHBP was temporarily implemented at the time of implantation of a permanent BiV system in patients referred for cardiac resynchronization therapy. Native conduction, DHBP, and BiV QRS duration were compared. All p... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125141 Thu, 08 Oct 2009 00:00:00 +0100 3125141 http://www.medworm.com/index.php?rid=3125139&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109011357%2Fabstract%3Frss%3Dyes Background: Peri-mitral atrial flutter (PMFL) is commonly encountered in patients undergoing atrial fibrillation (AF) ablation.Objective: The purpose of this study was to determine the electrophysiologic characteristics, procedural success, and medium-term outcomes in patients with PMFL.Methods: The study consisted of 50 consecutive patients (45 men and 5 women, age 57 ± 12 years) with PMFL following or during AF ablation. Of the 50 PMFLs, 24 occurred during AF ablation (16 at index ablation and 8 at repeat procedure for recurrent AF), and 26 developed during follow-up. Ablation of PMFL was performed by creating a linear lesion joining the mitral annulus to the left inferior pulmonary vein.Results: The incidence of PMFL was higher in patients with mitral isthmus (MI) ablation performed du... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125139 Thu, 08 Oct 2009 00:00:00 +0100 3125139 http://www.medworm.com/index.php?rid=3125151&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010844%2Fabstract%3Frss%3Dyes Background: Myocardial scar is a substrate for reentrant ventricular arrhythmias and is associated with poor prognosis. Fragmented QRS (fQRS) on 12-lead ECG represents myocardial conduction delays due to myocardial scar in patients with coronary artery disease (CAD).Objective: The purpose of this study was to determine whether fQRS is associated with increased ventricular arrhythmic event and mortality in patients with CAD and nonischemic dilated cardiomyopathy (DCM).Methods: Arrhythmic events and mortality were studied in 361 patients (91% male, age 63.3 ± 11.4 years, mean follow-up 16.6 ± 10.2 months) with CAD and DCM who received an implantable cardioverter-defibrillator for primary or secondary prophylaxis. fQRS included various RSR′ patterns (QRS duration (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125151 Mon, 05 Oct 2009 00:00:00 +0100 3125151 http://www.medworm.com/index.php?rid=2951824&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010467%2Fabstract%3Frss%3Dyes In the article titled “Free radical scavenger specifically prevents ischemic focal ventricular tachycardia” by Dezhi Xing, MD, Ashok K. Chaudhary, PhD, Francis J. Miller, Jr., MD, James B. Martins, MD, that published in the April 2009 issue of the Journal (Heart Rhythm 2009;6:530-6), was incorrect. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951824 Mon, 05 Oct 2009 00:00:00 +0100 2951824 http://www.medworm.com/index.php?rid=3205824&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010455%2Fabstract%3Frss%3Dyes Delayed cardiac repolarization can be caused by mutations in cardiac channel subunit genes, resulting in different forms of the congenital long QT syndrome (LQTS), or secondary to cardiac pathologies, such as the recently described Takotsubo cardiomyopathy. LQTS is characterized by QT-interval prolongation on the ECG, reflecting cardiac action potential prolongation. Takotsubo cardiomyopathy is a clinical syndrome characterized by transient ventricular wall-motion abnormalities and left ventricular dysfunction that primarily affects postmenopausal women. Frequent ECG alterations include ST-segment elevation and/or T-wave inversion, with occasional clear QT-interval prolongation. The etiology of Takotsubo cardiomyopathy is poorly understood. Patients often experience psychologically or phys... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205824 Fri, 25 Sep 2009 00:00:00 +0100 3205824 http://www.medworm.com/index.php?rid=2951788&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009928%2Fabstract%3Frss%3Dyes Moss and colleagues (N Engl J Med 2009 Sep 1; Epub, PMID 19723701) evaluated whether cardiac resynchronization therapy (CRT) reduces mortality and heart failure in patients with mild cardiac symptoms, reduced ejection fraction (EF), and wide QRS complex. Over 4.5 years, 1,820 patients with ischemic or nonischemic cardiomyopathy, EF ≤0.30, QRS ≥130 ms, and New York Heart Association class I or II symptoms were randomized in a 3:2 ratio to CRT with defibrillator (1,089 patients) or an implanted defibrillator (731 patients). The primary end-point was all-cause mortality or heart failure event, whichever occurred first. During follow-up of 2.4 years, 17.2% of patients in the CRT group and 25.3% in the defibrillator group experienced a primary end-point. The hazard ratio in favor of CRT was... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951788 Thu, 24 Sep 2009 00:00:00 +0100 2951788 http://www.medworm.com/index.php?rid=2951787&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009916%2Fabstract%3Frss%3Dyes Lalani et al (J Med Genet 2009;46:168, PMID 18812404) studied the relationship between bone morphogenetic protein (BMP) and Wolff-Parkinson-White syndrome (WPW). BMP is important in the development of annulus fibrosus in mice. The authors identified five individuals with nonrecurrent deletions of 20p12.3. Four of these individuals had WPW syndrome with variable dysmorphisms and neurocognitive delay. With the exception of one maternally inherited deletion, all occurred de novo, and the smallest of these harbored a single gene, BMP2. In two individuals with additional features of Alagille syndrome, deletion of both JAG1 and BMP2 were identified. The authors demonstrate a novel genomic disorder characterized by deletion of BMP2 with variable cognitive deficits and dysmorphic features and show... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951787 Thu, 24 Sep 2009 00:00:00 +0100 2951787 http://www.medworm.com/index.php?rid=3205826&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010327%2Fabstract%3Frss%3Dyes The objective of this article is to review the above anatomy and assess the ability of imaging to detect the proximity and orientation of these secondary structures in relation to the LA and the pulmonary veins (PVs). Lastly, we will discuss ablation strategies to avoid damage to these secondary structures. The imaging techniques described in this review include computed tomographic (CT) angiography, magnetic resonance angiography, and intracardiac echocardiography (ICE). (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205826 Tue, 22 Sep 2009 00:00:00 +0100 3205826 http://www.medworm.com/index.php?rid=3125149&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010431%2Fabstract%3Frss%3Dyes Background: Sudden cardiac arrest is a leading cause of death in industrialized countries, and ischemic ventricular fibrillation (VF) is a frequent cause.Objective: The purpose of this study was to determine whether patients with ST elevation myocardial infarction (STEMI) who develop ischemic VF show more overall RR-interval irregularity (RRI) than do STEMI patients without ischemic VF.Methods: Ischemic VF was identified in 41 patients from 1,473 digital 12-lead Holter recordings from three separate STEMI studies. Continuous 3-lead and 12-lead electrocardiogram (ECG) snapshots recorded every minute were compared between all ischemic VF patients and 123 random patients without ischemic VF. Time intervals from start of Holter to ischemic VF and equivalent intervals in the controls were used ... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125149 Tue, 22 Sep 2009 00:00:00 +0100 3125149 http://www.medworm.com/index.php?rid=3125148&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010443%2Fabstract%3Frss%3Dyes Background: Precise mechanisms that initiate ventricular tachycardia (VT) in the intact infarcted human heart have not been defined.Objective: The purpose of this study was to investigate the mechanisms that underlie human postinfarct VT initiation.Methods: Noncontact mapping of the left ventricle was performed in 9 patients (age 67.1 ± 7.8 years, ejection fraction 34.4% ± 5%) with previous myocardial infarction and sustained monomorphic VT.Results: Circuits in which ≥30% of the diastolic pathway (DP) could be defined were identified in 12 VTs (cycle length 357 ± 60 ms). Eighteen VT episodes were initiated with pacing, and one occurred spontaneously. Ten complete and two partial circuits were mapped (89% ± 25% of the DP). In all complete circuits, pacing led to the development of uni... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125148 Tue, 22 Sep 2009 00:00:00 +0100 3125148 http://www.medworm.com/index.php?rid=3125147&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010352%2Fabstract%3Frss%3Dyes Background: The etiology of accessory pathway (AP) formation is generally unknown.Objective: The purpose of this study was to test the hypothesis that AP formation is genetically mediated by examining whether AP location differs by sex and/or race, using sex and race as proxies to distinguish genetically different individuals.Methods: This was a single-center, retrospective cohort study of 282 consecutive patients undergoing their first electrophysiology study that revealed at least one AP between 2004 and 2008. Sex and race were compared with AP location determined by invasive electrophysiology study.Results: Eighty-nine (52%) males and 40 (36%) females had a left posterior AP (P = .006). Sixty-four (57%) females had a right annular AP, compared with 55 (32%) males (P (Source: Heart Rhyth... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125147 Tue, 22 Sep 2009 00:00:00 +0100 3125147 http://www.medworm.com/index.php?rid=3053833&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010339%2Fabstract%3Frss%3Dyes Precordial palpitation, developed by the ancient Greeks, gave the first observation of the normal rhythm of the heart. Since that time, understanding the substrate for this rhythm and how this substrate is regulated in heart disease has been an ever-expanding scientific endeavor. The targets, on the other hand, are getting smaller and smaller. Whole-heart studies have decreased in scope to electrophysiological studies of channels involved in generating the action potential. In turn, the understanding of individual protein subunits of the channels became the standard of excellence. The discovery that changes in protein levels were not always correlated with changes in gene activity (RNA production) indicates that the time to dig deeper has arrived. In this edition of Heart Rhythm, Girmatsio... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053833 Tue, 22 Sep 2009 00:00:00 +0100 3053833 http://www.medworm.com/index.php?rid=3125159&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010297%2Fabstract%3Frss%3Dyes Purkinje cells are specialized for rapid propagation in the heart. Furthermore, Purkinje fibers as the source as well as the perpetuator of arrhythmias is a familiar finding. This is not surprising considering their location in the heart and their unique cell ultrastructure, cell electrophysiology, and mode of excitation–contraction coupling. This review touches on each of these points as we outline what is known today about Purkinje fibers/cells. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125159 Fri, 18 Sep 2009 00:00:00 +0100 3125159 http://www.medworm.com/index.php?rid=3125153&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010303%2Fabstract%3Frss%3Dyes Conclusion: SAN dysfunction in AF is associated with Ca2+ clock malfunction, characterized by unresponsiveness to isoproterenol and caffeine and down-regulation of RyR2 in SAN. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125153 Fri, 18 Sep 2009 00:00:00 +0100 3125153 http://www.medworm.com/index.php?rid=3125152&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010340%2Fabstract%3Frss%3Dyes Background: Catheter ablation of the left atrium (LA) is associated with potential collateral injury to surrounding structures, especially the esophagus and the right phrenic nerve (PN).Objectives: The purpose of this study was to evaluate the efficacy and feasibility of intrapericardial balloon placement (IPBP) for the protection of collateral structures adjacent to the LA.Methods: Electroanatomic mapping was performed in porcine hearts using a transseptal endocardial approach in eight swine weighing 40–50 kg. An intrapericardial balloon was inflated in the oblique sinus, via percutaneous epicardial access, to displace the esophagus. Similarly, with the balloon positioned in the transverse sinus, IPBP was used to displace the right PN. Esophageal temperature was monitored while endocard... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125152 Fri, 18 Sep 2009 00:00:00 +0100 3125152 http://www.medworm.com/index.php?rid=3053823&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010285%2Fabstract%3Frss%3Dyes The initial decoding of a handful of human genomes in February 2001 ushered in a new age of genetic discovery that has revolutionized our understanding of health and disease. Over the last two decades, the genetic underpinnings of heritable cardiovascular disease have been unveiled with the discovery of rare pathogenic mutations that cause cardiac channelopathies and cardiomyopathies. In addition, the influence of common genetic variation (polymorphisms) on both physiology and pathology is slowly being illuminated. As technology has advanced, so has our ability to further interrogate the genome. With the completion of the final draft of the Human Genome Project in 2004, the International HapMap Project in 2005, and the ENCODE Project in 2007, a new wave of genetic association studies have ... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053823 Wed, 16 Sep 2009 00:00:00 +0100 3053823 http://www.medworm.com/index.php?rid=2951768&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010273%2Fabstract%3Frss%3Dyes Common atrial flutter (AFL), a macrorentrant circuit involving the right atrium (RA), is characterized by its dependence on the cavotricuspid isthmus (CTI), the latter demonstrated by concealed entrainment and successful termination of AFL during its ablation. Most components of the AFL reentrant circuit have been well described. Using various forms of activation sequence mapping, including the techniques of entrainment mapping and postpacing intervals (PPIs), the anterior and the posterior boundaries of AFL have been well defined. From these prior observations, it has been considered that the tricuspid annulus serves as the anterior boundary and the line of block between the superior and inferior vena cava as the posterior boundary of the AFL reentrant circuit. However, the superior porti... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951768 Wed, 16 Sep 2009 00:00:00 +0100 2951768 http://www.medworm.com/index.php?rid=3125140&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010017%2Fabstract%3Frss%3Dyes Conclusion: The survival rate after VT ablation has improved over time and may reflect improved mapping and ablation techniques, in addition to improved therapies for treatment of congestive heart failure. Tolerated VT and lack of inducible ventricular arrhythmias following VT ablation was associated with improved survival in this study, suggesting their value as a risk factor for subsequent mortality. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3125140 Mon, 14 Sep 2009 00:00:00 +0100 3125140 http://www.medworm.com/index.php?rid=3053820&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109010005%2Fabstract%3Frss%3Dyes Conclusion: Marked differences in device longevity among manufacturers cannot be explained by pacing mode, number of shocks, or pacing percentage only. Overall, device performance requires further improvement for the sake of patient health and cost. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053820 Mon, 14 Sep 2009 00:00:00 +0100 3053820 http://www.medworm.com/index.php?rid=3053814&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009990%2Fabstract%3Frss%3Dyes Background: Recent studies have shown that cryoablation and radiofrequency (RF) ablation are comparable with regard to success rates and safety in the treatment of common atrial flutter (AFL). Long-term success requires persistence of bidirectional conduction block (BCB) in the inferior cavotricuspid isthmus (CTI).Objective: The purpose of this study was to determine the persistence of BCB in a prospective randomized multicenter trial of the two ablation techniques.Methods: A total of 191 patients were randomized to RF ablation or cryoablation of the CTI using an 8-mm-tip catheter. In all patients, BCB was defined as the ablation end-point. Primary end-point of the study was nonpersistence of achieved BCB and/or ECG-documented relapse of common AFL within 3-month follow-up.Results: Acute s... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053814 Mon, 14 Sep 2009 00:00:00 +0100 3053814 http://www.medworm.com/index.php?rid=3205829&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009965%2Fabstract%3Frss%3Dyes We present an example of atrial tachycardia where, transiently, sequential V-V intervals are each shorter than the associated A-A intervals. AV node conduction behavior likely explains how this example initially seems to defy one of the fundamental principles of rhythm discrimination. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3205829 Fri, 11 Sep 2009 00:00:00 +0100 3205829 http://www.medworm.com/index.php?rid=3053832&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009849%2Fabstract%3Frss%3Dyes This study sought to evaluate changes in miR-1 and Kir2 subunit expression in relation to IK1 alterations in LA of patients with persistent AF.Methods: Atrial tissue was obtained from 62 patients (31 with AF) undergoing mitral valve repair or bypass grafting. Currents were recorded from isolated cells. Proteins were quantified from immunoblots. mRNA and miR-1 levels were measured with real-time polymerase chain reaction. Immunohistochemistry was applied to localize connexin (Cx) 43.Results: IK1 density was increased in LA cells from patients with AF (at −100 mV: −5.9 ± 1.3 vs. −2.7 ± 0.7 sinus rhythm, P (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053832 Mon, 07 Sep 2009 00:00:00 +0100 3053832 http://www.medworm.com/index.php?rid=3053828&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS154752710900993X%2Fabstract%3Frss%3Dyes Autonomic innervation of the heart involves both extrinsic and intrinsic cardiac autonomic nervous systems (CANS). The former collectively includes the ganglia in the brain or along the spinal cord and their axons (e.g., the vagosympathetic trunk) en route to the heart; the latter consists of the autonomic ganglia and axons located on the heart itself or along the great vessels within the pericardium. Ample structural and functional evidence indicates that the intrinsic CANS form a complex neural network composed of ganglionated plexi (GP) concentrated within epicardial fat pads and their interconnecting ganglia and axons. Indeed, Ardell has summarized the structural and functional concept of the intrinsic CANS as more than a simple relay station for the extrinsic autonomic projections to ... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053828 Mon, 07 Sep 2009 00:00:00 +0100 3053828 http://www.medworm.com/index.php?rid=3053824&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009898%2Fabstract%3Frss%3Dyes Conclusion: Ripple mapping allows activation of the myocardium to be tracked visually without prior assignment of local activation times and without interpolation into unmapped regions. It assists the identification of tachycardia mechanism and optimal ablation site, without the need for an experienced computer-operating assistant. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053824 Mon, 07 Sep 2009 00:00:00 +0100 3053824 http://www.medworm.com/index.php?rid=3053819&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009941%2Fabstract%3Frss%3Dyes Current guidelines from the American College of Cardiology (ACC), American Heart Association (AHA), and Heart Rhythm Society (HRS) provide indications for implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization devices with defibrillating capability (CRT-D). Class I indications, those for which benefits clearly outweigh risks and for which therapy is generally indicated, include secondary prevention for survivors of cardiac arrest due to ventricular fibrillation (VF) or ventricular tachycardia (VT); syncope and VF/VT inducible at electrophysiological study; left ventricular ejection fraction (LVEF) ≤35% due to prior myocardial infarction (MI; at least 40 days after infarct) with New York Heart Association (NYHA) class II-III heart failure (and NYHA class I if LVEF (S... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053819 Mon, 07 Sep 2009 00:00:00 +0100 3053819 http://www.medworm.com/index.php?rid=3053816&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009862%2Fabstract%3Frss%3Dyes Conclusions: Catheter ablation for AVNRT without fluoroscopic guidance is feasible and safe, and does not prolong procedure time. The reduction in radiation dose is considerable for patients and professionals. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053816 Mon, 07 Sep 2009 00:00:00 +0100 3053816 http://www.medworm.com/index.php?rid=3053815&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009953%2Fabstract%3Frss%3Dyes Conclusions: PVI assessment using a 3D electroanatomical system is as accurate as Lasso evaluation, with excellent concordance. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053815 Mon, 07 Sep 2009 00:00:00 +0100 3053815 http://www.medworm.com/index.php?rid=2951827&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009874%2Fabstract%3Frss%3Dyes We wish to thank Dr. Thomas for his interest and recognition that our recently published article on arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) filled a need to provide a comprehensive profile on patients newly diagnosed with this disease. Dr. Thomas expressed puzzlement by the omission of data regarding the right ventricular outflow tract (RVOT) in our cohort. From a historic point of view, in 1992, Ricci et al. reported that the maximal diameter of the RVOT by magnetic resonance imaging (MRI) in 15 patients with ARVC/D was 34 ± 6 mm compared with 21 ± 7 mm in patients with dilated cardiomyopathy (P >.0001). Recently, measurements of the RVOT by MRI from 42 probands from our National Institutes of Health registry were compared with those from 10 patients with idio... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951827 Mon, 07 Sep 2009 00:00:00 +0100 2951827 http://www.medworm.com/index.php?rid=2951826&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009886%2Fabstract%3Frss%3Dyes Marcus et al are to be congratulated for filling in a gap in our knowledge of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). Until now, the clinical features and results of diagnostic tests were known for patients with overt manifestations who often fulfilled the task force criteria. A similar strategy has been applied to describe familial disease among individuals who may or may not eventually be diagnosed with ARVC/D based on either task force criteria or modified task force criteria adapted to describe familial disease. What has been missing are data on newly diagnosed disease, a particularly vexing problem in contemporary clinical practice. The work of Marcus et al has answered some questions germane to this issue. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2951826 Mon, 07 Sep 2009 00:00:00 +0100 2951826 http://www.medworm.com/index.php?rid=3053830&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009370%2Fabstract%3Frss%3Dyes More than 150 years ago, Purkinje discovered the subendocardial fibers bearing his name, which were later recognized by Tawara to be the distal part of the conduction system. In his monumental work, Tawara recognized the difference between myocardial cells and the Purkinje fibers; however, this difference could not be confirmed in human hearts. Anatomically, these cells are located in the subendocardial layer of both ventricles and generate an interwoven network with branches penetrating the ventricular wall tangentially to the adjacent myocardial cells. More than 15 years ago, it was realized that a defibrillation shock has a different effect on the Purkinje fibers than on the ventricular muscle. Subthreshold stimulation of the Purkinje fibers and electroporation stabilized the ventricle ... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053830 Thu, 03 Sep 2009 00:00:00 +0100 3053830 http://www.medworm.com/index.php?rid=2837044&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109008819%2Fabstract%3Frss%3Dyes Since the landmark paper of Michel Haïssaguerre and colleagues, ablation methods have been applied increasingly in the treatment of atrial fibrillation (AF). A variety of procedures have been developed, none of which are uniformly effective, and improving their therapeutic efficacy is a significant challenge in clinical electrophysiology. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=2837044 Wed, 02 Sep 2009 23:00:00 +0100 2837044 http://www.medworm.com/index.php?rid=3053835&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009369%2Fabstract%3Frss%3Dyes Andersen-Tawil Syndrome (ATS) is an autosomal-dominant or sporadic disorder characterized by ventricular arrhythmias, periodic paralysis, and distinctive facial and skeletal dysmorphology. ATS is notable for its variable penetrance (not all subjects manifest all 3 phenotypes) and variable expressivity (the severity of the expressed phenotype varies considerably). The neuromuscular manifestations of ATS consist of intermittent weakness, often in the setting of progressive interictal weakness. The distinctive physical characteristics include low-set ears, micrognathia, syndactyly, clinodactyly, short stature, and scoliosis. Cardiac manifestations of ATS include QT and QU interval prolongation, prominent U waves, frequent premature ventricular contractions (PVCs), polymorphic ventricular tach... Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053835 Tue, 01 Sep 2009 00:00:00 +0100 3053835 http://www.medworm.com/index.php?rid=3053822&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009357%2Fabstract%3Frss%3Dyes Conclusion: We show an association between a common TGFBR2 polymorphism and risk of SCA caused by VA in the setting of CAD. If validated, these findings support the role of genetic variation in TGFß signaling in SCA susceptibility. (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053822 Tue, 01 Sep 2009 00:00:00 +0100 3053822 http://www.medworm.com/index.php?rid=3053829&cid=s_35616_7_f&fid=35616&url=http%3A%2F%2Fwww.heartrhythmjournal.com%2Farticle%2FPIIS1547527109009278%2Fabstract%3Frss%3Dyes Conclusions: The PS is proarrhythmic in that it provides pathways that prolong activity, and it plays a supplementary role in maintaining the later stages of reentry (>800 ms). (Source: Heart Rhythm) Heart Rhythm journals http://www.medworm.com/rss/comments.php?id=3053829 Tue, 25 Aug 2009 00:00:00 +0100 3053829