Abstract
Background : Reentrant ventricular outflow tract (OT) tachycardia is rare in patients with non-ischemic heart disease. Ventricular tachycardia (VT) originating from the aortic sinus cusp (ASC) regions usually seems to be focal or nonreentrant mechanism. It has been often unclear whether the reentrant circuit exists in OT and ASC. Objectives : The purpose of this study was to evaluate whether it is possible to identify the reentry circuit between ASC and OT using entrainment mapping techniques. Methods : We performed the electrophysiological study in 51 consecutive patients (26 men and 25 women, mean age 50.3 ± 14.5 years, range 26 to 77 years) with symptomatic VT arising from OT. As a result, the reentrant VTs were observed in 6 patients. To examine a VT circuit, pacing for entrainment and radiofrequency (RF) catheter ablation were performed on 8 reentrant VTs in 6 patients. Result : Pacing for entrainment was performed at 93 sites in these VTs and 52 sites where the post-pacing interval was identical to VT cycle length were reentry circuit sites; 6 sites in ASC, 43 sites below the aortic valve and 3 sites in right OT below the pulmonary valve. Reentry circuit sites were identified as exit (n=7), central-proximal (n=1), inner loop (n=19) and outer loop (n=25). RF ablation terminated VT at 4 sites of 6 total ASC sites and 4 sites of 46 total OT sites (p=0.0002). Conclusions : Reentry circuit is identified in ASC and OT in patients with non-ischemic OT-VT. Entrainment mapping was useful as a guide for RF catheter ablation even in ASC.
