The recognition and prevention of border zone cerebral ischaemia during cardiac surgery.

Four patients who sustained bilateral occipital and parietal lobe ischaemia during cardiac surgery for coronary artery bypass are described. The features include cortical blindness, visual disorientation, disturbances of reading and constructional dyspraxia. The symptoms tended to improve over about six weeks and good visual acuity was regained in all instances. The likeliest cause is generalized cerebral hypotension. Ischaemic injury might be prevented by prior detection of extracranial arterial disease and by monitoring cerebral as well as cardiac activity during surgery.