J.B. is a well‐trained male with syncope due to paroxysmal AV nodal heart block who ultimately required a permanent pacemaker despite an initial attempt at cessation of training only. Baseline sinus node function was normal, but AV nodal conduction remained abnormal even after autonomic blockade supporting intrinsic AV nodal dysfunction. This case illustrates that vigorous physical training may unmask previously unrecognized intrinsic dysfunction of AV nodal conduction or, as previously reported for physical training induced sinus node dysfunction, cause AV nodal dysfunction. Simple cessation of training to treat this problem is often recommended but may not be adequate for some patients who remain at risk for recurrent syncope during the deconditioning period.
More than 1 in 10 patients may develop recurrence of conduction after undergoing a successful radiofrequency catheter ablation procedure. The physiologic basis for recurrence following successful ablation procedures remains uncertain. The purpose of this study was to evaluate the role of electrode temperature as a predictor of recurrence following radiofrequency catheter ablation procedures.The subjects of this study were 538 patients who underwent a successful attempt at radiofrequency catheter ablation of AV nodal reentrant tachycardia, an accessory pathway, and/or the AV junction. Patients were followed for a mean of 215 +/- 138 days. Conduction recurred in 35 (6.5%) of the 538 patients. Recurrence of conduction occurred in 25 (9.3%) of 270 patients undergoing ablation of an accessory pathway, 7 (3.5%) of 201 patients undergoing ablation of AV nodal reentrant tachycardia, and in 3 (4.5%) of 67 patients undergoing ablation of the AV junction. The electrode temperature achieved at successful sites associated with recurrence was not different from the temperature achieved at successful sites without recurrence (61.1 +/- 8.9 vs 61.6 +/- 9.1; P = 0.8). The likelihood of developing a recurrence was higher following ablation of accessory pathways than following ablation of AV nodal reentrant tachycardia or the AV junction (P = 0.03). Patients experiencing a recurrence following ablation of an accessory pathway had longer procedure durations (P = 0.0001). Ablation of left free-wall pathways was associated with a lower incidence of recurrence as compared with all other locations (P = 0.008).The results of this study suggest that electrode temperature at the successful ablation site cannot be used to identify patients at highest risk of recurrence.
Rhythm control could become the preferred treatment strategy for atrial fibrillation (AF) if the available antiarrhythmic agents were more effective and safe. A subanalysis of the AFFIRM trial data suggested that rhythm control, if achieved without the adverse effects related to antiarrhythmic medications, may offer a significant survival advantage over rate control. This article reviews the new investigational pharmacologic and dietary agents being considered for the prevention and treatment of AF. Dronederone is a benzofurane similar to amiodarone, but without the iodine component, and is devoid of many of the amiodarone systemic toxicities. Azimilide is a delayed rectifier potassium channel blocker with use‐dependent effects. Agents that target the ultra rapid component of the delayed rectifier potassium current (I Kur ) have atrial myocyte specific properties and may be devoid of QT prolongation and torsade de pointes in clinical usage. Newer agents being studied also include fish oil, gap junction modulators, 5HT4 receptor antagonists, angiotensin‐converting enzyme inhibitors, angiotensin II receptor blockers, and HMG CoA reductase inhibitors. There is considerable hope that at least some of these agents will ultimately be available for more effective and safe clinical treatment and prevention of AF.
1) understand the different patterns of myocardial fibrosis and the degree of isoform-expression and phosphorylation changes in cardiomyocyte titin in the different hemodynamic subgroups of aortic stenosis; 2) examine the extent of myocardial remodeling in paradoxical aortic stenosis to help better understand the poor prognosis of these patients; and 3) review the current guidelines and management of severe aortic stenosis, including evaluation focused on hemodynamic subtypes.
A 15-year-old girl with a history of paroxysmal supraventricular tachycardia underwent an electrophysiology study (EPS) for diagnosis and ablation. Her baseline electrocardiogram and echocardiogram were normal. At EPS, she had dual atrioventricular nodal (AVN) conduction, but isoproterenol was needed to initiate the slow-fast form of AVN reentry. Before ablation without any isoproterenol, she began to have a spontaneous block in the fast pathway with continuous conduction over the slow pathway. After ablation of the slow pathway, all complexes conducted over the fast pathway during a 25-year follow-up. Possible electrotonic interaction between the slow and fast pathways is proposed as the mechanism for this phenomenon.
Substrate-based ablation for ventricular tachycardia (VT) using Ripple map (RM) is an effective treatment strategy for patients with ischemic cardiomyopathy but has yet to be evaluated in patients with nonischemic cardiomyopathy (NICMO). The aim of this study is to determine the feasibility and effectiveness of an RM-based ablation for NICMO patients.This was a single-center, retrospective study including all NICMO patients undergoing VT ablation at St Vincent Hospital between January 1, 2018 and January 12, 2019. Retrospective RM analysis was performed on those that had a substrate-based ablation to identify the location and number of Ripple channels as well as their proximity to ablation lesions. Thirty-three patients met the inclusion criteria and had a median age of 65 (58, 73.5) with 15.2% of the population being female, and were followed for a median duration of 451 (217.5, 586.5) days. Of these patients, 23 (69.7%) had a substrate-based ablation with a median procedural duration of 196.4 (186.8, 339) min, 1946 (517, 2750) points collected per map, and 277 (141, 554) points were within the scar. Two (8.6%) procedural complications occurred, and 7 (30.4%) patients had VT recurrence during follow-up. RM analysis revealed an average of two Ripple channels and the patients without VT recurrence had ablation performed closer to the Ripple channels: 0 (0, 4.7) versus 14.3 (0, 23.5) cm; p = .02.An RM-based substrate ablation can be performed in NICMO patients and ablation within Ripple channels is a predictor of VT freedom.
