Preferential Pathway Pacing within the Aortic Sinus of Valsalva: Strong Evidence for the Existence of Preferential Conduction with Different Exit Sites Traversing the Ventricular Septum.

A 57-year-old male who presented with frequent ventricular premature contraction (VPC) was referred for catheter ablation. Two different QRS morphologies (VPC1 and VPC2) were recorded. Pace mapping at the right ventricular outflow (RVOT) was identical to VPC1 without latency. During the mapping within the right sinus of Valsalva where the RF applications were successful for elimination of VPC, discrete prepotential was recorded and the pace mapping produced both VPC1 and VPC2 morphology with different latency. These electrophysiological findings were thought to prove the existence of preferential pathway traversing the ventricular outflow septum with different exit sites.