Left Bundle Pacing in a Patient with Atrio-Ventricular Canal Defect Presenting with Atrial Standstill and Junctional Bradycardia

A 37-year-old woman with a history of incomplete atrioventricular canal and an extensive history of corrective cardiac surgeries presented with recurrent episodes of acute decompensated heart failure in the presence of junctional bradycardia with chronotropic incompetence. The initial plan was to proceed with implantation of a dual chamber pacemaker but given high index of suspicion for the presence of atrial standstill in the context of her extensive cardiac surgical history, we performed electroanatomical mapping and echocardiography at the time of pacemaker implantation that confirmed atrial standstill. Islands of electrically functional atrial myocardium were detected. Pacing from these locations resulted in local atrial capture, but failed to result in global atrial electrical capture, mechanical atrial contraction, or atrioventricular conduction. In light of the dismal outcomes of right ventricular pacing in patients with atrial standstill, we implanted a left bundle branch pacing lead that resulted in improvement of patient's cardiac output and prevented future admissions for decompensated heart failure in one year follow up.