Abstract 5688: Identification of Unusual Reentry Circuit Sites of Non-Ischemic Left Ventricular Outflow Tract Tachycardia
Reentrant left ventricular outflow tract tachycardia is rare in patients with non-ischemic heart disease. Ventricular tachycardia (VT) from the aortic sinus cusp regions usually seems to be focal or nonreentrant mechanism. To assess the presence of slow conduction and reentry circuit sites between the aortic sinus cusp and ventricular outflow tract during left ventricular outflow tract tachycardias using entrainment mapping techniques. Of 13 consecutive patients with symptomatic VT arising from left ventricular outflow tract 8 VTs in 6 patients demonstrated evidence of reentry. Pacing for entrainment was performed from 93 sites in these VT and entrainment was demonstrated at 52 sites; 6 sites in the aortic sinuses, and 46 sites below the aortic valve. 41 sites were bystanders that were not in the reentry circuit. Reentry circuit sites identified were exit (n=7), central/proximal (n=1), inner loop (n=19), outer loop (n=25). Ablation terminated VT at 4 sites of 6 total aortic sinus cusp sites and 4 sites of 46 total ventricular outflow tract sites (p=0.03). Reentry is a cause of some VTs that occur in the left ventricular outflow tract, both in the aortic sinuses and below the aortic valve, in nonischemic heart disease. Entrainment mapping was useful as a guide for catheter ablation even in aortic sinus cusp.