Congenital absence of superior vena cava: unusual anomaly of superior systemic veins complicating pacemaker placement.

Congenital anomalies of the superior systemic veins can complicate placement of transvenous pacemaker electrode leads. Persistent left superior vena cava is the most common congenital anomaly; in this paper, we describe the case of a patient who had congenital absence of both superior venae cavae, which has not been reported previously. The superior systemic veins drained into persistent double azygos veins subdiaphragmatically. The anomaly was verified by venography. Temporary cardiac pacing was established by passing the electrode lead through the femoral vein, and a permanent epicardial pacemaker lead was placed thereafter. This appears to be the first recorded case of such an anomaly.