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Evidence for improved cerebral function after minimally invasive bypass surgery
B BhaskerRao1, D VanHimbergen, H L Edmonds
1Cardiovascular Research Center, Department of Surgery, University of Louisville School of Medicine, Kentucky 40292, USA.
Insights
Off-pump coronary artery bypass surgery significantly reduces cerebral microemboli and neurocognitive deficits compared to on-pump procedures. This suggests cardiopulmonary bypass is a key factor in post-cardiac surgery neurological impairment.
Area of Science:
- Cardiovascular Surgery
- Neuroscience
- Medical Technology
Background:
- Neurological impairment is a significant complication following cardiac surgery.
- Cerebral microemboli during cardiopulmonary bypass (CPB) are implicated in post-operative neurological deficits.
- Coronary artery bypass grafting (CABG) presents risks for neurological complications.
Purpose of the Study:
- To evaluate and compare cerebral dysfunction after on-pump versus off-pump coronary artery bypass surgery.
- To investigate the relationship between cerebral microemboli and neurocognitive outcomes.
- To assess the impact of cardiopulmonary bypass on neurological integrity.
Main Methods:
- A cohort of 322 patients undergoing coronary artery bypass graft (CABG) surgery was studied.
- Cerebral microemboli were monitored using transcranial Doppler (TCD) to detect high-intensity transient signals (HITS).
- Neurocognitive function was assessed postoperatively using the antisaccadic eye movement (ASEM) test.
Main Results:
- The on-pump group generated significantly more cerebral microemboli (HITS) than the off-pump group.
- Patients undergoing off-pump surgery demonstrated superior performance on the ASEM test, with 94% achieving perfect scores.
- A significant proportion of on-pump patients (35.4%) had impaired ASEM test results, indicating neurocognitive deficits.
Conclusions:
- Cerebral dysfunction, measured by ASEM errors, is more prevalent after on-pump coronary bypass surgery.
- Off-pump bypass surgery is associated with a lower incidence of cerebral dysfunction.
- Reduced cerebral microemboli during off-pump procedures likely contribute to better neurological outcomes.
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.
Conclusion:
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.