Asymptomatic superior vena caval occlusion: a complication of nonthoracotomy implantation of cardioverter defibrillator.

A patient with ischemic dilated cardiomyopathy and history of ventricular fibrillation received an implantable cardioverter defibrillator by the nonthoracotomy approach. Four years later, during elective replacement of an exhausted pulse generator, a superior vena caval thrombotic occlusion with collateral circulation through the azygos and emiazygos vein systems was documented. This occlusion occurred despite an anticoagulant treatment in the standard therapeutic range. We speculate that thrombotic occlusion might be secondary to a mechanical vessel injury.