Neurologic complications of coronary artery bypass grafting: diffuse or focal ischemia?

The central nervous system complications arising during or shortly after coronary artery bypass grafting are due to cerebral ischemia associated with hypotension and to embolism. Hemodynamic compromise produces a spectrum of disturbance of consciousness and mentation ranging from brain death and coma through the chronic vegetative state to mild confusion. Watershed infarction may add to this picture focal deficits such as visual disorientation and cortical field defects or bibrachial weakness (the "man in a barrel" syndrome). Macroembolism accounts for most perioperative strokes and is related to cardiac arrhythmias, to intracardiac thrombus, and particularly to the severity and friable nature of any aortic atheroma. Microembolism can cause focal problems in the watershed territory but is normally responsible for diffuse changes as seen in the neuropsychologic sequelae of coronary artery bypass grafting. Coexistent carotid artery disease rarely contributes to the postoperative neurologic changes.