Cardiac electrophysiologic procedures - A ten years' experience at National Institute of Cardiovascular Diseases, Karachi.

OBJECTIVE: To review 10 years of clinical practice of cardiac electrophysiology study and radiofrequency catheter ablation in the treatment of supraventricular tachycardia. METHODS: The retrospective chart review was conducted at the National Institute of Cardiovascular Diseases, Karachi, and comprised records of all patients who underwent electrophysiological study and / or radiofrequency catheter ablation from January2007 to December 2016. SPSS 21 was used for data analysis. RESULTS: Of the 627 patients, 335(53.4%) were females. The overall mean age was 40.99}13.59 years. The major indication for procedure was supraventricular tachycardia 376(59.97%). Final electrophysiological study diagnosis was typical slow fast atrioventricular nodal re-entrant tachycardia in 303(48.3%) patients. The overall success rate was 472(75.3%). Procedure-related complications were reported in 25(4%) patients, and there was 1(0.15%) mortality. CONCLUSIONS: Cardiac electrophysiology studies and radiofrequency catheter ablation were found to be an effective and safe method for diagnosis and treatment of supraventricular tachycardia.

Follow-Up of a Prospective Surgical Strategy to Prevent Intra-Atrial Reentrant Tachycardia After the Fontan Operation.

BACKGROUND: Intra-atrial reentrant tachycardia (IART) after the Fontan operation had an early reported incidence of 10% to 35% during early and intermediate follow-up and posed substantial management challenges. METHODS AND RESULTS: To reduce the incidence of IART after the Fontan procedure, we performed a randomized, double-blind study to evaluate the impact of an incision in the right atrium joining the lateral tunnel suture line and the tricuspid valve annulus. Between March 1998 and September 2003, 134 subjects (median age: 1.8 years; range: 1.3-5.2 years; 91 men) were randomly assigned to receive the incision. All 134 patients had a form of single ventricle pathological anatomy. The clinical course, electrocardiograms, and Holter monitoring were available for review in 114 subjects at a median of 8.2-year follow-up (range: 0.9-11.9 years). There were 2 late deaths, neither subject had IART. The combined incidence of sustained IART was 3.5% (4/114). There was no difference in the occurrence of sustained IART between those subjects receiving the incision and those who did not (2 in each group) during follow-up. No patients of either group experienced short-term complications. CONCLUSIONS: Despite the fact that the primary outcome of this trial was not reached, the most significant finding was that with current management, the incidence of IART is considerably lower than the early retrospective, observational studies suggested.

Clinical significance of induced left atrial macro-reentrant tachycardia after pulmonary vein isolation.

BACKGROUND: The clinical significance of induced left atrial macro-reentrant tachycardia (LA-AT) after encircling pulmonary vein isolation (EPVI) is unclear. Our objective was to determine whether induced LA-ATs are associated with the clinical recurrence of ATs. METHODS: We studied 185 consecutive patients with paroxysmal atrial fibrillation (PAF) who underwent their first EPVI with an 8-mm tip, nonirrigated catheter approach. AT was induced by atrial burst pacing after the completion of EPVI, and the atrial activation pattern was evaluated using EnSite NavX. Induced LA-ATs were ablated only in patients with clinical ATs of suspected LA origin. The factors associated with occurrence of AT after the procedure were examined. RESULTS: LA-ATs were induced in 38 patients and ablated in 5 patients. During a follow-up of 23 ± 7 months, the occurrence of AT did not differ between patients with nonablated LA-ATs (4/33, 12 %) and those without any inducible ATs (16/113, 14 %, p > 0.99). In multivariate analysis, the number of ablation points for completing EPVI was the only independent predictor of AT occurrence (odds ratio 1.07, p < 0.01). A repeat procedure was performed in 22 of 26 patients who developed AT. Nineteen patients became free from AT and AF after ablation of the conduction gaps (EPVI, n = 17; another line, n = 4), extra PV firing (n = 4), focal AT (n = 4), and induced LA-ATs (n = 3). CONCLUSIONS: In patients who had EPVI for PAF using an 8-mm tip, nonirrigated catheter, the occurrence of AT after EPVI was mainly due to conduction gaps in the ablation line or extra PV triggers. In patients with PAF, LA-ATs induced during the first procedure did not require ablation if they were not associated with clinical AT.

Intra-atrial reentrant tachycardia in adult patients after Fontan operation.

BACKGROUND: Atrial tachyarrhythmia is a major late complication in adult Fontan patients. This study examined the clinical features and risk factors of late intra-atrial reentrant tachyarrhythmia (IART) in adult patients after Fontan surgery and the mid-term outcome of Fontan conversion with or without antiarrhythmic surgery in these patients. METHODS: We conducted a retrospective study on adult patients who were born before 1994 and survived at least 3 months after a Fontan operation at Seoul National University Children's Hospital. RESULTS: We followed 160 patients over 20.9 ± 4.1 years. Sustained atrial tachycardia was identified in 51 patients, and IART was found in 41, appearing a mean 13.6 years after surgery. By the 25 year follow-up, 40% had developed IART. The incidence of IART significantly increased over time. Patients with an atriopulmonary connection (APC) (n=65) had significantly longer follow-up duration and higher incidence of IART than patients with a lateral tunnel (n=86) or extracardiac conduit Fontan (n=9). On multivariate analysis, APC, sinus node dysfunction, and nonsustained atrial tachycardia were found to be significantly associated with IART. Twenty-four patients with IART underwent Fontan conversion. Over the follow-up period, IART severity scores in the 22 patients who survived after Fontan conversion decreased significantly, and New York Heart Association functional class significantly improved. On multivariate analysis, protein losing enteropathy and ventricular dysfunction were found to be significant risk factors for mortality. CONCLUSIONS: IART was common in adult Fontan patients, and Fontan conversion with or without antiarrhythmic surgery and pacemaker placement helped to control it.

Bundle branch reentrant ventricular tachycardia: cumulative experience in 48 patients.

INTRODUCTION: The clinical, electrophysiologic features and follow-up of 48 patients with inducible bundle branch reentrant (BBR) tachycardia are presented. METHODS AND RESULTS: Forty-eight patients were identified in whom a diagnosis of BBR tachycardia was made during electrophysiologic evaluation. The clinical presentation was syncope or sudden death in 38 patients, and sustained palpitations during wide QRS complex tachycardia in 5 patients. Electrophysiologic studies were performed in 5 additional patients for various other reasons. Structural heart disease was present in 45 patients. Idiopathic dilated cardiomyopathy and coronary artery disease were the anatomical substrates in 19 (39%) and 24 (50%) patients, respectively, severe aortic regurgitation was present in 2 patients, and no organic heart disease was identified in 3. All 48 patients had evidence of His-Purkinje system disease. BBR tachycardia with left and right bundle branch block morphologies was induced in 46 and 5 patients, respectively, and interfascicular BBR tachycardia was initiated in 2 patients. Ventricular tachycardia of a myocardial origin was induced in 11 patients. Management of BBR tachycardia included transcatheter bundle branch ablation in 28 patients, and antiarrhythmic drug therapy in 16 patients. Four patients were treated with implantable defibrillators. After a mean follow-up of 15.8 months in 42 patients, there were 13 deaths due to congestive heart failure, 4 sudden cardiac deaths, 3 nonsudden cardiac deaths, and 3 noncardiac related deaths. CONCLUSION: Sustained BBR, a form of monomorphic ventricular tachycardia, is a highly malignant arrhythmia usually seen in patients with structural heart disease. Three different types of BBR tachycardia are described. If distinguished from ventricular tachycardia of a myocardial origin, catheter ablation of the right bundle branch can be easily performed and effectively eliminates BBR. During follow-up, congestive heart failure is the most common cause of death in this population.