Neuropsychological dysfunction following elective cardiac operation. I. Early assessment

Two neuropsychological tests were administered to 227 men and women, ages 25 to 69 years, before and after coronary bypass and cardiac valve operations to provide current information regarding the incidence of postoperative decrements in neuropsychological dysfunction and the factors associated with them. Biographical, psychological, and medical-surgical data were studied together with changes in scores on the Trail Making Tests and the Visual Reproduction (VR) Test of the Wechsler Memory Scale (WMS). Postoperative decrements greater than one standard deviation were observed in each of the four scores derived from these testings for 11% to 17% of the patients. Yet 70% of all patients remained within one standard deviation of original performance on all four scores. Among the preoperative correlates of significantly reduced test performance were age greater than 60 years, end-diastolic pressure greater than 30 mm Hg, moderate to severely enlarged heart size on preoperative x-ray film, and use of propranolol or chlordiazepoxide hydrochloride. Significant perioperative correlates included measure of duration of operation (such as total time of operation greater than 7 hours, time on the pump greater than 2 hours, and aortic cross-clamp time greater than 2 hours), total estimate of blood loss greater than 2,000 ml, hypotension, difficult intubation, and insertion of an intra-aortic balloon. Postoperative factors significantly associated with declines in test scores included electrolyte (Na+, K+, Cl-) abnormalities, longer stay in the intensive care unit, bizarre behavior or disorientation, and depression score. These findings suggest that those patients with more precarious heart function, a more protracted operation, and/or increased metabolic disturbances are especially prone to neuropsychological dysfunction following cardiac operations.