Abstract 18466: Electrophysiologic Characteristics of Para-Hisian Atrial Tachycardia
Background: Focal atrial tachycardias (ATs) appear to arise from preferential sites, including the tricuspid and mitral annuli. ATs arising from the atrioventricular annuli are initiated and terminated with programmed stimulation, and are, in general, adenosine- and verapamil-sensitive. Para-Hisian AT arising from the apex of the Triangle of Koch has been reported to be a distinct entity with unique electrophysiologic characteristics. We sought to better characterize their electrophysiologic properties in a large series of patients.
Methods and Results: The study population consisted of 28 pts (63 ± 17 yrs; 18 F) with AT arising from the para-Hisian region. The ATs were focal and originated from the region of the anteroseptal tricuspid annulus, in close proximity to the His bundle recording. Proximity to the His bundle and centrifugal activation pattern were confirmed by fluoroscopy and/or three-dimensional mapping. The mean AT cycle length was 422 ± 70 ms. AT was incessant in one pt, and initiated and terminated by programmed stimulation in all other cases. Adenosine (4.9 ± 1.5 mg) terminated AT in 23/24 patients. Intravenous verapamil terminated AT in 3/3 patients. Catheter ablation was attempted in 21 pts and was successful in 19 (90%). In three patients, ablation was performed and was successful from the non-coronary aortic valve cusp.
Conclusions: The para-Hisian region is a source of focal AT, with properties consistent with ATs arising from elsewhere along the tricuspid and mitral annuli. Therefore, they should be considered a subset of this broader group of ”annular” ATs. Prior reports hypothesizing that para-Hisian AT is due to reentry were limited by the lack of complete delineation of the reentrant circuit. The electropharmacologic findings in this series of para-Hisian ATs are most consistent with cyclic AMP-mediated triggered activity.
- © 2010 by American Heart Association, Inc.