Background. To examine the effect of screening the aorta for atheroma before aortic manipulation and use of exclusive Y graft revascularization on the incidence of neuropsychological dysfunction after coronary artery bypass. Methods. Aortic atheroma was detected using epiaortic and transesophageal echocardiography. Atheroma avoidance was facilitated by use of the exclusive Y graft technique, which has no aortic coronary anastomoses. In the control group aortic atheroma was assessed by manual palpation, and we attempted to avoid any atheroma detected. In this group we also used aorta-coronary grafts. Transcranial Doppler imaging of the right middle cerebral artery was used to detect cerebral microemboli. Neuropsychological dysfunction was defined as a 20% or more decline in score for at least 20% of a neuropsychometric battery of ten tests for each patient. Results. Late dysfunction at 57 ± 2 days postoperatively in the control group was 38.1% and in the echo/Y group was 3.8% (p' = 0.012). Microemboli detected by transcranial Doppler imaging during periods of aortic manipulation was greater for those with late dysfunction (5.2 ± 3.0 compared with 0.5 ± 0.2) (p' = 0.018). No clinical strokes occurred in either group. Conclusions. The combined techniques of epiaortic screening and exclusive Y graft for coronary artery bypass operations resulted in a low incidence of late neuropsychological dysfunction. (C) 2000 by The Society of Thoracic Surgeons.