Methods to access the surgically excluded cavotricuspid isthmus for complete ablation of typical atrial flutter in patients with congenital heart defects

Background: Cavotricuspid isthmus (CVTI)-dependent flutter in postoperative congenital heart disease patients is common and difficult to treat. Objective: The purpose of this study was to evaluate techniques for accessing excluded portions of the CVTI after Fontan or atrial switch procedures and completely ablating flutter. Methods: Patients who had undergone Fontan or atrial switch procedures and had CVTI-dependent flutter requiring ablation between 1990 and 2007 were identified. Flutters induced, methods for accessing the CVTI, use of intracardiac echocardiography, complications, and success rates were noted. Results: Sixteen patients (44% males, mean age at ablation 28 years) were identified: 14 prior Fontan and 2 Mustard repair, with a total of 19 ablation procedures. In 13 (81%) of 16 patients, access to the entire CVTI could not be achieved via a systemic venous route. The excluded CVTI was accessed by retrograde transaortic approach in 6 and by anterograde transconduit puncture in 1 patient, with termination and lack of reinducibility of CVTI-dependent flutter achieved in all cases. One patient developed high-grade AV block requiring pacemaker therapy. Follow-up data (range 1-89 months, mean 29 months) were available for 18 of 19 procedures. CVTI atrial flutter recurred in 1 of 7 patients involving access to the pulmonary venous side. Conclusion: Even when surgical procedures exclude a portion of the CVTI, complete ablation of "typical" atrial flutter, including documentation of bidirectional block, can be achieved by novel approaches targeting the surgically excluded arrhythmogenic atrial tissue.