[Persistent left superior vena cava and absence of right superior vena cava].

Persistence of left superior vena cava is a rare finding. The combination of persistent left superior vena cava and absent right superior vena cava with no other congenital cardiovascular abnormalities has been exceptionally reported. We describe a case of persistent left superior vena cava and absent right superior vena cava observed during pacemaker implantation and confirmed by transthoracic contrast echocardiography.