Stroke associated with coronary artery bypass surgery.

Medical records and neuroimaging studies of 30 patients with major neurologic events after coronary artery surgery were reviewed. Two thousand and twenty-nine coronary artery bypass graft operations were performed in our institution between October 15, 1985, and December 27, 1989. Of these, there were 30 documented neurologic events suggesting acute ischemic injury during the intraoperative or the postoperative period. Clinical manifestations included hemiparesis, monoparesis, aphasia, bilateral cortical dysfunction, cortical and brainstem dysfunction, and left homonymous hemianopsia. There were five deaths directly attributable to neurologic injury. Twenty-two patients had a CT scan of the head, of which 15 showed evidence of acute infarction, two suggested watershed lesions from cerebral hypoperfusion, and the remainder showed findings consistent with multiple cerebral emboli or primary intracranial occlusion. Five carotid arteriograms and one digital subtraction arteriogram of the carotids were obtained. Angiographic findings revealed two common carotid artery occlusions, one callosal marginal artery occlusion, and two cases of bilateral high-grade internal carotid stenoses. Our findings support the contention that in patients who suffer cerebral infarction associated with coronary artery bypass grafting, the main mechanism of injury is cerebral embolization rather than cerebral hypoperfusion.