Po-05-224 identification of cavotricuspid isthmus conduction block – pitfall of differential pacing maneuver.

Differential pacing (DP) maneuver was generally used to assess bidirectional block of cavotricuspid isthmus (CTI) after catheter ablation. Nevertheless, in some cases, DP maneuver could be inaccurate in identification of bidirectional CTI block. The purpose of the study is to identify limitation of DP maneuver and suggest continuous sequence (CS) maneuver as a complement of differential pacing maneuver. Patients who were diagnosed to typical atrial flutter and underwent catheter ablation were enrolled. CTI conduction block was evaluated by two maneuvers, DP and CS maneuver. We tried to identify CTI conduction block for each patient with both maneuvers. Differential pacing maneuver was conducted according to conventional protocol. With CS maneuver, CTI conduction block was assessed with the recorded sequence of diagnostic catheter. Sixty two patients were investigated. Two maneuvers were performed in all patients. There were 8 cases (8/62, 12.9%) of discrepancy between the result of CS and DP maneuver. One of discrepancy cases, CTI conduction block was identified with CS maneuver, but insufficient conduction block with DP maneuver. The rest of discrepancy (11.2%) cases were the opposite. DP could not guarantee bidirectional block of CTI because of anatomical complexity and catheter instability. CS maneuver found incomplete block over 10% of conventional maneuver. CS maneuver is simple and can be complement to overcome limitation of DP maneuver.