Intracardiac and surface electrocardiogram (ECG) recordings during electrophysiologic (EP) study in Wolff-Parkinson-White syndrome

Shown are five surface ECG leads (I, aVF, V1, V3, V6) and intracardiac recordings from the high right atrium (HRA), lateral mitral annulus (HBE1-2 and HBE3-4), coronary sinus (proximal to distal, CS9-10, CS7-8, CS5-6, CS3-4, and CS1-2), and the right ventricular apex (RVA3-4). During the diagnostic electrophysiology study, orthodromic atrioventricular reentrant tachycardia was induced. Recordings from the CS demonstrated that the earliest site of ventricular activation was at CS7-8, indicating a left lateral location of the accessory pathway (arrow). The mapping catheter (HBE1-2,3-4) was advanced through a patent foramen ovale to the lateral mitral annulus. Activation mapping was used to select the ablation site; during sinus rhythm, the ablation catheter was maneuvered to the site along the mitral annulus, which recorded earliest ventricular activity (HBE1-2) (ie, the atrial [A] and ventricular [V] electrograms recorded from the ablation catheter tip were continuous and the local ventricular activity preceded the onset of the delta wave on the surface ECG).