Posthypoxic encephalopathy in patients undergoing coronary artery bypass surgery: clinical, neuropsychological, and neuroimaging aspects

Abstract

Posthypoxic encephalopathy is a frequent complication after coronary artery bypass surgery (CABG), which includes stroke, early postoperative delirium, and postoperative cognitive dysfunction (PCD). The more pronounced prevalence and severity of the latter during surgery using extracorporeal circulation are currently being discussed.Objective: to analyze various types of cerebral dysfunction in patients undergoing CABG and to determine the role of perioperative factors in its development.Patients and methods. The investigation enrolled 53 patients who had undergone elective CABG for coronary heart disease. Group 1 included 20 patients who had undergone beating-heart surgery; Group 2 comprised 33 patients, in whom CABG had been performed using extracorporeal circulation (ECC). Neuropsychological testing and brain magnetic resonance imaging (MRI) (structural and functional techniques) were carried out.Results and discussion. Posthypoxic encephalopathy was diagnosed in 10 and 67% of patients in Group 1 and 2, respectively (p=0.05); these were precisely all the three types of brain dysfunction which were observed in Group 2 patients. Factors, such as over 70 years of age; median level of education; smoking; body mass index >30 kg/m2 ; ejection fraction <50%; class III effort angina; >210-min surgery duration; >55-min aortic ligation; and >115-min ECC, showed a statistically significant association with the onset of PCD (p<0.05). In Group 2, MRI revealed a weaker positive functional relationship of the medial prefrontal cortex with the posterior cingulate gyrus (<0.005); 18% of patients were found to have acute ischemic zones.Conclusion. Surgical myocardial revascularization using ECC is associated with a greater likelihood of PCD than beating-heart CABG. The factors that favored the development of PCD, such as increased age, low preoperative cognitive status, smoking, and long-term use of ECC, were identified when applying ECC.