98-05: Prophylactic Catheter Ablation of the Arrhythmogenic Substrate for Total Cavo-pulmonary Connection Candidates with Isomerism

Abstract

Background: The substrates of supraventricular tachycardia (SVT) are often associated with right atrial isomerism (RAI) and left atrial isomerism (LAI) that are candidates for total cavo-pulmonary connection (TCPC) procedure. Since SVT can be a serious complication and is mostly difficult to be cured by catheter ablation (CA) because of access limitation to the heart after TCPC. Therefore, pre-operative electrophysiological evaluation seems important to prospect the risk of SVT. The purpose of this study is to delineate the incidence of arrhythmogenic substrates in TCPC candidates with isomerism and evaluate the result of prophylactic CA before TCPC. Patients: From January 2010 to December 2015, we performed electrophysiological study (EPS) upon 20 consecutive patients (RAI in 15 and LAI in 5) before TCPC. Median age was 3 years and median weight was 13 kg. Spontaneous narrow QRS tachycardia had been demonstrated at the palliative operation and/or diagnostic catheterization in all patients. All patients were associated with complete atrioventricular (AV) septal defect. Results: We confirmed that distinct His bundle electrograms recorded at the anterior aspect (1 patients) the posterior aspect (2 patients) or both sides of the common AV valve (17 patients). The type of SVT was AV reentrant tachycardia (AVRT) involving twin AV nodes in 12 patients, uncommon AV nodal reentrant tachycardia (AVNRT) in 1, common atrial flutter (AFL) around common AV valve in 2 and incisional atrial reentrant tachycardia in 5. We achieved successful CA in 19 patients (95%). We could not complete the isthmus block line for AFL in only one failed case after replacement of artificial common AV valve. In 12 patients with AVRT involving twin AV nodes, we performed CA of unilateral AVN which showed recessive anterograde conduction. Iatrogenic ventricular dyssynchrony after CA was never observed in all 12 cases of our series. We could eliminate uncommon AVNRT by modification of one posterior AV node. One clinically significant complication of a stuck artificial common AV valve occurred after successful CA for AFL. The mean follow-up period was 3 years. In all patients after CA no recurrence of SVT was observed. Nineteen patients underwent TCPC procedure successfully and safely. Conclusion: Prophylactic CA of arrhythmogenic substrates in TCPC candidates with isomerism heart may be an effective therapeutic option.