Steal syndrome after internal mammary artery bypass grafting--an entity with increasing significance.

Stenosis of proximal subclavian artery (SCA), malformations of the internal mammary artery (IMA) at its origin, or large IMA side branches may cause myocardial ischemia due to blood-steal through a patent IMA graft. Thirty-one cases of postoperative steal syndromes have been reported in the literature, 23 due to proximal SCA stenosis, seven due to large IMA side branches and one due to an IMA malformation. We report two additional cases and discuss them in conjunction with the cases in the literature. Thirty patients suffered from recurrent angina pectoris, three had asymptomatic reversal of flow in the IMA as diagnosed by coronary angiography during routine follow-up examination. Carotid-subclavian bypass grafting is the treatment of choice for the management of proximal SCA stenosis. IMA malformations or large side branches are treated by interruption of the responsible vessel, either by ligation or by transarterial catheter embolization. In 82% (27 of 33), steal syndrome could have been prevented by preoperative angiography of the IMA. We advocate it as a routine procedure in combination with coronary arteriography.