Coronary steal by internal mammary graft with subclavian stenosis

The internal mammary artery was used for 66 of 312 grafts in 100 patients. One vessel was not used because of damage, but in no other case was any reason found for witholding the internal mammary graft. Brachial pulsation and blood pressure were normal and the sectioned mammary artery bled more than 50 ml. per minute, but subclavian bruits were not routinely sought. In other series there has been a 0.5 to 2 per cent incidence of subclavian stenosis in subjects requiring coronary grafts. A case is presented in which subclavian stenosis was mild and undetected. The lesion caused a reversal of flow in the mammary shunt when the purse-string suture around cannula was tied and protamine and vasodilators were given. The patient died--the only death in the series. Had coronary artery steal been suspected, it could easily have been recognized and corrected, and the patient's survival assured. Awareness of its possibility and careful clinical screening of patients, with subclavian arteriograms whenever doubt exists, should reduce the risk. Distally based mammary grafts may invite this complication, and nondirectional flowmeters make its recognition less easy.