New simplified technique for 3D mapping and ablation of right ventricular outflow tract tachycardia.

OBJECTIVE: To evaluate the safety and efficacy of using a circular multielectrode catheter for mapping and ablation of ventricular tachycardia (VT) or premature ventricular complexes (PVCs) from the right ventricular outflow tract (RVOT). BACKGROUND: Three-dimensional (3D) mapping systems are commonly used for mapping and ablation of RVOT VT and PVCs. Newer catheters that are circular with multiple electrodes, such as the Lasso catheter, are capable of simultaneously recording from multiple points within a circumferential plane. Given the tubular structure of the RVOT, these catheters could be used for mapping tachycardias from the RVOT. METHODS: A retrospective cohort study of patients undergoing radiofrequency (RF) ablation of RVOT VT or PVCs was performed. In group 1 (n = 7), mapping was performed with a single ablation catheter and fluoroscopy. In group 2 (n = 10), 3D mapping using ESI (n = 9) or CARTO (n = 1) was performed. In group 3 (n = 12), mapping was performed with a circular multielectrode catheter (n = 12). All ablations were performed with 4-mm tip catheters using RF energy. RESULTS: Catheter ablation for RVOT VT (n = 15) or PVCs (n = 14) was performed on 29 cases in 26 patients, 9 males. Mean age was 35.9 years. In groups 1, 2, and 3, the mean number of lesions was 17.7 +/- 7.7, 13.6 +/- 7.7, and 18.2 +/- 22.7 and the median number of lesions was 20, 13, and 5, respectively. There were no significant differences in the number of lesions, RF time, fluoroscopy time, procedure time, and acute success rate among the three techniques. There were three complications in group 2 and one in group 3. CONCLUSION: The use of a circular multielectrode catheter is as effective as the other standard available 3D mapping techniques, both in terms of procedural success and procedural characteristics. Additionally, because of the lower cost associated with using the circular multielectrode catheter approach, further evaluation should be performed to determine whether this is the most cost-effective approach to 3D mapping and ablation of RVOT tachycardias.

Radiofrequency ablation of atrial flutter: a randomized controlled study of two anatomic approaches.

Atrial flutter often results from a macroreentrant circuit that uses anatomic structures within the right atrium as its borders. RF ablation at the site of an obligatory isthmus can eliminate the atrial flutter circuit. The aim of this study was to compare two approaches to atrial flutter ablation: the septal (septal aspect of the tricuspid valve annulus to coronary sinus ostium and Eustachian ridge) approach versus the posterior (inferior vena cava to tricuspid valve annulus) approach. Twenty patients were randomized to either the "septal" or "posterior" approach. Entrainment mapping and/or confirmation of bidirectional isthmus conduction at baseline were performed in those patients in atrial flutter and normal sinus rhythm, respectively. RF ablation was performed with standard catheters and techniques. Crossover was permitted after two lines of RF lesions. Endpoints included acute success rates and fluoroscopy times. There was no statistically significant difference in the success rate between the two approaches using intention-to-treat analysis. Fluoroscopy times in the septal versus posterior approaches were 58.4 +/- 30.3 versus 70.8 +/- 31.1 minutes, respectively (P = 0.7). There was more frequent crossover in patients assigned to the septal approach and the one major complication, atrioventricular block, also occurred using this approach. There was no statistically significant difference in the success rate or fluoroscopy times between the septal and posterior approaches to atrial flutter ablation. However, given the risk of atrioventricular block with the septal approach, the posterior approach should be the preferred initial choice.

Prevention and management of chronic heart failure with electrical therapy.

Sudden cardiac death is responsible for >40% of patients with heart failure losing their lives. Thus, the prevention of life-threatening cardiac arrhythmias is a major goal in the management of heart failure. In several randomized clinical trials, electrical therapy with the implantable cardioverter defibrillator (ICD) has proved superior to medical antiarrhythmic therapy in both the secondary and primary prevention of sudden cardiac death in patients with reduced left ventricular function. In addition to the severity of left ventricular dysfunction, the etiology of the cardiomyopathy appears to be a determinant in the benefit derived from this form of electrical therapy. Whereas patients with ischemic cardiomyopathy clearly show improved survival with ICD therapy, outcome data in patients with nonischemic cardiomyopathy are less convincing. The major challenge lies in the risk stratification of patients with heart failure for arrhythmic death. Catheter ablation is another form of electrical therapy that can help in the treatment of patients with heart failure. In patients with a tachycardia-mediated cardiomyopathy because of drug-refractory atrial fibrillation with rapid ventricular response, catheter ablation of the atrioventricular node and pacemaker implantation can effectively restore a physiologic heart rate, often with dramatic regression of left ventricular dysfunction. In patients with frequent ICD therapies because of frequent recurrences of ventricular tachyarrhythmias, catheter ablation of ventricular tachycardia can be an effective adjunctive therapy. New catheter ablation techniques and new atrial pacing algorithms can also significantly reduce the atrial fibrillation burden in patients with heart failure who are particularly susceptible to decompensation because of atrial fibrillation. Pacing for hemodynamic benefit in heart failure has evolved from dual-chamber pacing modes with optimized atrioventricular delay to biventricular pacing resulting in cardiac resynchronization. This new treatment modality for advanced heart failure has been shown to result in significant symptomatic and hemodynamic improvement.

Long QT syndrome: a preventable cause of sudden death in women.

Long QT syndrome is a hereditary disorder of cardiac ion channels causing abnormal electrical activation of the heart and leading to life-threatening ventricular tachycardia. Syncope, ventricular tachycardia, or sudden cardiac death in the absence of structural heart disease is the typical presentation, often starting in childhood. Women are more commonly affected by both the congenital form and the drug-induced acquired form of this disease and are particularly at risk in the postpartum period. The long QT syndrome can be recognized by a prolonged QT interval on the electrocardiogram. Several mutations in six genes encoding subunits of cardiac potassium and sodium channels have so far been identified, and gene-specific epidemiology, risk stratification, and management are emerging. beta-blockers are the mainstay of therapy for primary prevention of cardiac events and implantable defibrillators for secondary prevention. Patient education, screening of family members, and increasing awareness of this disorder among physicians are important steps toward prevention of sudden death in these otherwise healthy young individuals.