Abstract 12183: The Reentry Circuit of Sinoatrial Reentrant Tachycardia Involves the Sinoatrial Exit Pathways in Humans: Observation by Noncontact Mapping System
Recent canine data suggested that sinoatrial node is functionally insulated from the surrounding atrium with discrete sinoatrial exit pathways (SEPs). We assessed the hypothesis that the impulse origin during sinus rhythm (SR) is multicentric through the conduction of SEPs, and that the reentry circuit of sinoatrial reentrant tachycardia (SART) involves the SEPs.
Methods and Results: Noncontact mapping of right atrium was performed in 4 patients with SART. Activation was, first, recorded during spontaneous SR, and SR immediately after overdrive atrial pacing and after administration of isoproterenol and ATP. These maneuvers usually revealed 3 main atrial breakthroughs (superior, middle, inferior) along crista terminalis. Each site was separated by distances greater than 1cm, and the earliest activation site shifted to each other, accompanied by the change of P wave morphology. In all patients, tachycardia was reproducibly induced and terminated by program stimuli, suggesting that reentry is the underlying mechanisms. The activation of tachycardia showed focal pattern and the earliest activation site was identical to one of the exit sites during SR, with the same P wave morphology. The earliest activation site of SART was identical to the middle atrial breakthrough during SR in 3 patients, and identical to the inferior breakthrough in 1 patient. Point ablation at the earliest activation site terminated the tachycardia, and the activation from the identical breakthrough during SR also disappeared. Thus, the direct diagnosis of SART could be made. After ablation, the earliest activation occurred from the superior breakthrough during spontaneous SR in all patients. In 3 patients where the middle breakthrough site was ablated, the atrial activation pattern from the superior breakthrough was changed after the ablation. This phenomenon could be explained by the bifocal atrial activation during SR. Before ablation, atrium is first activated through the superior, and then through the middle exit pathway shortly after. But after the ablation of the middle SEP, the atrium was activated solely through the superior SEP.
Conclusions: These results suggest that SEPs exist in Humans and that the reentry circuit of SART involves the SEPs.
- © 2011 by American Heart Association, Inc.