Infra-Hisian Atrioventricular Block

A quadripolar catheter was placed at the Hisbundle region. At baseline, the patient was in sinus rhythmwith 2:1 AV block with RBBB on conducted beats (see Fig. 1A). Intracardiac recordings demonstrated infra-Hisian block with nonconducted beats (Fig. 2). Intermittently, 1:1 AV conduction would resume, sometimes, but not always, following a premature atrial contraction (PAC) with RBBB aberrancy, followed by LBBB with the 1:1 conducted beats (see Fig. 1B;