RISK-FACTORS AND SOLUTIONS FOR THE DEVELOPMENT OF NEUROBEHAVIORAL CHANGES AFTER CORONARY-ARTERY BYPASS-GRAFTING

Background. As operative mortality for coronary artery bypass grafting has decreased, greater attention has focused on neurobehavioral compl ications of coronary artery bypass grafting and cardiopulmonary bypass . Methods. To assess risk factors and to evaluate changes in surgical technique, between 1991 and 1994 we evaluated 395 patients undergoing coronary artery bypass grafting with an 11-part neurobehavioral batter y administered preoperatively and at 1 and 6 weeks postoperatively. Pa tients were instrumented with 5-MHz focused continuous-wave carotid Do ppler transducers intraoperatively to estimate cerebral microembolism as an instantaneous perturbation of the velocity signal. Microembolism data were quantitated and compared with surgical technical maneuvers during operation and with neurobehavioral deficit (greater than or equ al to 20% decline from preoperative performance on two or more neurobe havioral tests) postoperatively. These data and patient demographics w ere statistically analyzed (chi(2), t test) and the results at 2 years (1991 and 1992; group A) were used to influence surgical technique in 1993 and 1994 (group B). Results. Significantly associated with new n eurobehavioral deficits were increasing patient age (p < 0.05), more t han 100 emboli per case (p < 0.04), and palpable aortic plaque (p < 0. 02). Group B patients had a significant decline in the neurobehavioral event rate (group A, 69%, 140/203; versus group B, 60%, 115/192; p < 0.05) of postoperative neurobehavioral deficits at 1 week and at 1 mon th (group A, 29%, 52/180; versus group B, 18%, 35/198; p < 0.01). The stroke rate was less than 2% in both groups (p = not significant). Mod ifications of surgical technique used in group B patients included inc reased use of single cross-clamp technique, increased venting of the l eft ventricle, and application of transesophageal and epiaortic ultras ound scanning to locate and avoid trauma to aortic atherosclerotic pla ques. Conclusions. Neurobehavioral changes after coronary artery bypas s grafting are common and associated with cerebral microembolization. Surgical technical maneuvers designed to reduce emboli production may improve neurobehavioral outcome. (C) 1997 by The Society of Thoracic S urgeons.