Cerebral emboli detected by transcranial Doppler during cardiopulmonary bypass are not correlated with postoperative cognitive deficits.
OBJECTIVE
High-intensity transient signals (HITS) are the transcranial Doppler representation of both air and solid cerebral emboli. We studied the frequency of HITS associated with different surgical maneuvers during cardiopulmonary bypass for coronary artery bypass graft surgery and their association with postoperative cognitive dysfunction (POCD).


METHODS
We combined 356 patients undergoing coronary artery bypass graft from 2 clinical trials who had both neuropsychological testing (before, 1 week and 3 months after surgery) and transcranial Doppler during cardiopulmonary bypass. HITS were grouped into periods that included: cannulation, cardiopulmonary bypass onset, aortic crossclamp-on, aortic crossclamp-off, side clamp-on, side clamp-off, and decannulation. POCD was defined by a decreased combined Z-score of at least 2.0 or reduction in Z-scores of at least 2.0 in 20% of the individual tests.


RESULTS
Incidence of POCD was 47.3% and 6.3% at 1 week and 3 months after surgery. There was no association between cardiopulmonary bypass counts of HITS and POCD at 1 week (P=0.617) and 3 months (P=0.110). No differences in HITS counts were identified at any of the surgical periods between patients with and without POCD. Factors affecting HITS counts were surgical period (P<0.0001), blood flow velocity (P=0.012), cardiopulmonary bypass duration (P=0.040), and clinical study (P=0.048).


CONCLUSIONS
Although cerebral microemboli have been implicated in the pathogenesis of POCD, in this study that included low-risk patients undergoing coronary artery bypass surgery, there was no demonstrable correlation between the counts of HITS and POCD.
Rodriguez
Rosendo A
RA
Division of Cardiac Surgery, University of Ottawa Heart Institute, Room H-5508, 40 Ruskin Street, Ottawa, Ontario K1Y 4W7, Canada. Rrodriguez@ottawaheart.ca
Rubens
Fraser D
FD
Wozny
Denise
D
Nathan
Howard J
HJ
D000368:Aged; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D003072:Cognition Disorders / Q000000981:diagnostic imaging / Q000209:etiology*; D005260:Female; D006801:Humans; D020766:Intracranial Embolism / Q000150:complications* / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D018570:Risk Assessment; D016896:Treatment Outcome; D017585:Ultrasonography, Doppler, Transcranial