VDD pacing in persistent left superior vena cava.

Although persistent left superior vena cava (PLSVC) is the most common major venous anomaly of the heart, associated absence of the right superior vena cava with normal visceral situs is exceedingly rare. Such a patient presented with complete heart block requiring permanent pacing. This was achieved successful using a single lead VDD system via the PLSVC with atrial sensing in the coronary sinus.