The effect of coronary artery bypass surgery on brain perfusion.

ABSTRACT

UNLABELLED Coronary artery bypass grafting (CABG) is one of the major treatment methods of coronary artery disease. CABG is an open-heart surgery that uses cardiopulmonary bypass (CPB). After CPB, it is well known that neurological and neuropsychological complications may occur. The purpose of this study was to evaluate brain perfusion patterns before and after CPB and to locate brain perfusion changes in patients with neurological and neuropsycological complications after CPB. METHODS: Twenty-five patients who underwent open-heart surgery (22 CABG, 3 valve replacement) and 5 patients (4 cholecystectomy, 1 periferic vascular surgery) as a control group were included in the study. The 99mTc-HMPAO injected dose was 925 MBq. Brain perfusion SPECT images were obtained 30-60 min postinjection using a dedicated triple-head brain SPECT camera. Imaging was performed 1 wk before and 4-6 wk after surgery. Technetium-99m-HMPAO brain SPECT slices were evaluated visually and semiquantitatively. RESULTS: None of the patients had severe neurologic complications. Neuropsychological deficits occurred in eight patients after CABG. Cognitive deterioration and depressive mood occurred in five patients. Disorientation, agitation and confusion periods were present in another two patients. Frontal hypoperfusion was found in these patients by visual and semiquantitative evaluations (p = 0.0277) and left parietal hypoperfusion was also present semiquantitatively (p = 0.0277). Visual hallucinations occurred in one patient. Computed tomography of these patients was normal. No perfusion abnormalities were observed in the patient with visual hallucinations and in patients without symptoms after open-heart surgery nor in the control group. Brain SPECT was repeated in two symptomatic patients 5 mo after CABG. Frontal hypoperfusion became normal, and these patients' symptoms disappeared. CONCLUSION: The results of this study indicate that regional cortical hypoperfusion may occur in patients with neuropsychological complications after CABG. Technetium-99m-HMPAO brain SPECT is a useful method to locate and determine brain perfusion changes after CABG.