A Case of Atrioventricular Reentrant Tachycardia Via a Left Posterior Accessory Pathway Located at Adjacent to the Leftward Extension of the Atrioventricular Node

Perspective from E-journals in J-STAGE

Abstract

A 45-year-old male with a history of prior ablation procedure for atrioventricular reentrant tachycardia（AVRT）via a left accessory pathway（AP）at another hospital in 2002 was referred to our institution for recurrent supraventricular tachycardia（SVT）in 2016. The earliest atrial activation during right ventricular（RV）pacing was located at posterior left atrium without decrement property. The clinical SVT with a tachycardia cycle length（TCL）of 344 ms with ventricular-atrial（VA）interval of 142 ms was easily induced by catheter manipulation. The retrograde atrial activation sequence during the SVT was identical to that of RV pacing. RV entrainment pacing revealed the “VAV” response with post-pacing interval - TCL of 108 ms and stimulus-atrial - VA interval of 82 ms, and captured the His potential in a antegrade fashion, indicating orthodromic AVRT with the left posterior AP. Although the VA interval was slightly prolonged after radiofrequency application to the site with earliest atrial activation via transseptal access, the retrograde atrial activation sequence remained unchanged. The findings of VA block with the adenosine triphosphate injection and atrioventricular nodal（AVN）pattern during para-Hisian pacing suggested the successful elimination of AP. The fact that the eccentric atrial sequence remained after ablation might be due to the residual conduction of the leftward extension of the slow pathway located close to the AP. In cases like this, electrophysiologists should be aware of the presence of the AVN leftward extension when the eccentric atrial sequence persists after the elimination of left posterior AP.