Intracardiac and surface ECG recordings during electrophysiologic study post-radiofrequency ablation of accessory pathway in Wolff-Parkinson-White

Shown are five surface leads (I, AVF, V1, V3, and V6) and intracardiac recording from the high right atrium (HRA), lateral mitral annulus (HBE1-2 and HBE3-4), coronary sinus proximal to distal (CS9-10, 7-8, 5-6, 3-4, 1-2), and right ventricular apex (RVA3-4). The tip of the mapping catheter is positioned at the site along the mitral annulus recording the earliest ventricular activity (HBE1-2) (ie, the location of the accessory pathway). Within a few beats after the application of radiofrequency energy (RF on), the delta wave on the ECG disappeared (arrow) and the PR interval normalized. Prior to ablation, the recordings from the CS catheter show continuous atrial (A) and ventricular (V) electrograms; after ablation, there is a normal interval between A and V.