Evidence for improved cerebral function after minimally invasive bypass surgery.
BACKGROUND
Neurological impairment is a major cause of morbidity after cardiac surgery and may be associated with occurrence of cerebral microemboli generated during cardiopulmonary bypass (CPB). This study evaluates cerebral dysfunction following coronary artery surgery on-pump and off-pump.


METHODS
Neurological outcome was evaluated in 322 patients with a coronary artery bypass graft (CABG). Conventional CPB was used (on-pump) in 305 patients and in 17 patients no CPB was used (off-pump). Intraoperatively, a pulsed-wave transcranial Doppler with a 2-MHZ probe measured high-intensity transient signals (HITS) by ultrasonic insonnation of the middle cerebral artery indicating the presence of emboli within the vessel lumen. Transcranial near-infrared spectroscopy measured cerebral venous oxygen saturation for adequate perfusion. Postoperatively, all patients were subjected to the antisaccadic eye movement (ASEM) test, a sensitive indicator of neurocognitive deficits secondary to frontal lobe dysfunction.


RESULTS
While there was no significant difference in O2 saturation, the number of microemboli HITS generated was significantly higher in the on-pump group than the off-pump group. In the off-pump group, 16 (94%) of 17 patients had perfect scores on the ASEM test, while only 108 (35.4%) of 305 patients achieved a perfect score in the on-pump group (p < 0.01). Furthermore, while all patients in the off-pump group achieved at least 90%, 28% (86/305) in the on-pump group scored "zero" on the ASEM test.


CONCLUSIONS
Cerebral dysfunction as evidenced by ASEM errors is common following coronary bypass on-pump, but rare with off-pump bypass surgery. Cerebral microemboli generated during CPB may account for this difference.
BhaskerRao
B
B
Cardiovascular Research Center, Department of Surgery, University of Louisville School of Medicine, Kentucky 40292, USA.
VanHimbergen
D
D
Edmonds
H L
HL
Jaber
S
S
Ali
A T
AT
Pagni
S
S
Koenig
S
S
Spence
P A
PA
D002315:Cardiopulmonary Bypass; D002493:Central Nervous System Diseases / Q000453:epidemiology / Q000517:prevention & control*; D002560:Cerebrovascular Circulation / Q000502:physiology; D001026:Coronary Artery Bypass / Q000379:methods*; D006801:Humans; D002542:Intracranial Embolism and Thrombosis / Q000453:epidemiology / Q000517:prevention & control*; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D016343:Monitoring, Intraoperative; D009460:Neurologic Examination; D011183:Postoperative Complications / Q000453:epidemiology / Q000517:prevention & control*; D012438:Saccades / Q000502:physiology; D017585:Ultrasonography, Doppler, Transcranial