CEREBRAL EMBOLI AND COGNITIVE OUTCOME AFTER CARDIAC-SURGERY

There have been major advancements in cardiac surgery over the past tw o decades, with a concomitant decrease in mortality and major morbidit y. However, several recent studies have demonstrated that cardiac surg ery poses significant risk for negative neurologic and neuropsychologi c outcome. Although very few patients die as a result of cardiac surge ry, more than two thirds of the patients demonstrate evidence of neuro psychologic dysfunction postoperatively. The mechanisms contributing t o post-cardiopulmonary bypass neuropsychologic deficits are uncertain. However, two major interrelated etiologic factors, hypoperfusion and emboli, are suggested as probable culprits. It is important to define the relationship between these two putative mechanisms and postoperati ve neuropsychologic outcome in order to either prevent the problem or treat the effects of emboli or hypoperfusion. For example, if embolism is the cause of the deficits, increasing cerebral perfusion would del iver more emboli and increase the amount and severity of injury. Conve rsely, if hypoperfusion is the cause of the injury, then decreasing br ain blood flow would increase the likelihood of injury. If both are im portant, their relative significance must be established, then one pre vented and the effects of the other treated. This report discusses the methodology for detecting cerebral emboli during cardiac surgery. The incidence and severity of neuropsychologic deficits after cardiac sur gery are discussed, as well as emboli in relation to composition and t ime of occurrence and their effect on neuropsychologic outcome. Copyri ght (C) 1996 by W.B. Saunders Company.