Abstract 19728: Translesional Time to Determine Complete Bidirectional Block Across the Cavotricuspid Isthmus

Abstract

Introduction: The goal of ablation of typical atrial flutter is to create complete bidirectional block across the cavotricuspid isthmus (CTI). The purpose of this study was to document whether there was a transisthmus time that is associated with complete bidirectional isthmus block (CBIB). Methods: Thirty consecutive patients who had CTI ablation procedures were assessed. A circular right atrial mapping catheter, coronary sinus catheter, and electroanatomical mapping were used in all patients. Before ablation, points were marked medial and lateral to the planned line and bidirectional conduction times were assessed. Post ablation bidirectional conduction times were assessed again at the points medial and lateral to the line. The translesional time (TL) was defined as the difference in bidirectional conduction time recorded lateral to the line from medial to the line. CBIB was verified by reversal of activation of the right atrium on the circular mapping catheter and/or documentation of widely spaced double potentials. Results: CBIB was achieved in 29/30 patients. The average baseline counterclockwise (CCW) conduction time across the CTI was 43 +/- 22 msec The average baseline clockwise (CW) conduction time was 42 +/- 16 msec. The average baseline TL was 10 msec CCW, and 9 msec CW. The longest baseline TL was 52 msec CCW and 28 msec CW . Post ablation, the average CCW conduction time was 149 msec, and CW was 150 msec in patients with CBIB. The average TL in patients with CBIB was 116 msec CCW and 111 msec CW. The shortest TL associated with CBIB was 90 msec CCW and 91 msec CW. The maximum TL associated with incomplete block was 68 msec. Conclusions: A bidirectional TL of greater 90 msec was predictive of CBIB after typical atrial flutter ablation, and could be used simplify assessment of CBIB during CTI ablation.