Blood-brain Barrier Disruption Following Cardiopulmonary Bypass: Assessment by Postoperative Magnetic Resonance Imaging

Background: Cardiopulmonary bypass (CPB) elicits a systemic inflammatory response that may result in disruption of the blood-brain barrier (BBB). This may be one of the mechanisms accounting for postoperative neurological dysfunction. Disruption of the BBB can be currently identified by magnetic resonance imaging (MRI) reflected by post contrast FLAIR images enhancement of the subarachnoid space. We aimed to determine whether (1) CPB elicits BBB disruption, (2) location of BBB injury with correspondence to neuropsychological tests and (3) duration till resolution.

Methods: Eight consecutive patients referred to coronary artery bypass grafting were assigned to undergo serial cerebral MRI evaluations. Designated MRI examinations were performed preoperatively, on postoperative days 1 and 5. Neuropsychological tests were administered twice: one day preoperatively and 5 days after surgery.

Results: There were no MRI signs of embolization in any of the patients. BBB disruption was demonstrated on postoperative day 1 in all patients. This disruption underwent resolution on postoperative day 5. Location of the BBB disruption was either generalized or confined to the parietal and frontal lobes. Neuropsychological test results exhibited a decrease in global cognitive score, predominantly in executive functions which corresponds to frontal lobe dysfunction.

Conclusion: Our study showed a correlation between postoperative BBB disruption location and the particular cognitive function that declines.
We therefore suggest that the mechanism for post cardiac surgery brain damage is BBB disruption rather than embolization.