Dual-Chamber Pacemaker Implantation Through a Persistent Left Superior Vena Cava With Absent Right Superior Vena Cava: The Alpha-Loop Technique

Persistent left superior vena cava (PLSVC) is the most common thoracic venous anomaly, but its coexistence with an absent right superior vena cava (RSVC) is uncommon and may make transvenous cardiac device implantation technically challenging. A 56-year-old woman with recurrent syncope and complete atrioventricular block underwent temporary pacing followed by planned dual-chamber permanent pacemaker implantation. Left -sided venography demonstrat ed drainage through a PLSVC into the coronary sinus and right atrium. Right-sided venography showed drainage through the innominate vein into the PLSVC, confirming absence of the RSVC. Because the coronary sinus-to-tricuspid valve trajectory was unfavorable for direct right ventricular lead delivery, the ventricular lead was advanced through the PLSVC and coronary sinus into the right atrium, and an alpha-loop was created using stylet manipulation. This facilitated prolapse of the lead across the tricuspid valve and stable positioning at the right ventricular apex. A right atrial lead was also successfully positioned, and satisfactory acute pacing parameters were obtained. Recognition of anomalous systemic venous anatomy and deliberate loop formation can permit conventional transvenous dual-chamber pacing in patients with PLSVC and absent RSVC.