Neurological complications of open heart surgery

Soon after the development of cardiopulmonary bypass procedures for open heart surgery, reports began to appear indicating that neurological complications occurred frequently { 1). Despite refinements in the apparatus used for cardiopulmonary bypass and improvements in the intraoperative techniques since that time, neurological disorders continue to be reported. The types of abnormalities described include stroke, seizures, hypoxic encephalopathy, delirium, specific disorders of higher cerebral function, and visual field defects [l-41. Many studies also mention focal motor and sensory disorders, peripheral neuropathy, and bra-chial plexus injury {4}. Other symptoms considered to be psychiatric in nature include insomnia, anorexia, depression, hostility, disorientation, hallucinations, and delusions [2). The reported incidence of the neurological complications of open heart operations varies widely depending upon the type of study, ranging from 7 to 61% for transient and from 1.6 to 23% for permanent complications [ 2). As might be expected, the incidence is much higher in prospective (28.7% incidence in a literature review of 804 patients) than in retrospective (11.9% incidence in a literature review of 1,787 patients) studies [2f. Even among prospective studies, however, the incidence varies substantially. In one study of 204 patients, for example, the incidence of neurological complications was 16.2 %L for transient and 6.4% for persisting abnormalities [21. In another study of 3 12 patients, however, transient complications occurred in 61% [4). Despite the high incidence of transient complications in this latter study, the number of patients with persisting neurological impairments was small 14). Neurological complications resulted in death in 1 patient (0.3%), and severe disability occurred in 4 (1.396). Forty-eight patients were mildly disabled during the immediate postopera-tive interval, and the remaining 138 with neurological abnormalities had no serious functional disability {41. Retrospective evaluations give considerably lower rates of postoperative neurological complications than careful prospective assessments. In a recent retrospective study, for example, a review of 1,667 patients who underwent coronary artery bypass graft surgery showed 7 5 cerebral complications, including altered mental state, stroke, and seizure in 64 patients (3.8%) [3). Altered mental state occurred in 57 patients (3.496), including delirium and hypoxic-metabolic en-cephalopathy. Cerebral infarction occurred in 13 (0.8%). The mortality rate in patients with a neurolog-ical complication was 27%. In several recent studies, psychomotor performance has been evaluated carefully both preoperatively and postoperatively IS). The results demonstrated clear deterioration of performance, most frequently among patients with gross neurological deficits. Relatively little attention has been paid to the …