Cerebral emboli detected during bypass surgery are associated with clamp removal.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasonography detects embolic signals during coronary artery bypass surgery. The relationship between embolization and specific events of bypass surgery is unclear. METHODS: With this technique, 20 patients undergoing bypass surgery were continuously monitored from inception to discontinuation of bypass. RESULTS: Embolic signals were detected in all patients. Of all embolic signals, 34% were detected as aortic cross-clamps were removed, and another 24% as aortic partial occlusion clamps were removed. Only 5% were detected at inception of bypass. Rates for embolization were 15.15 embolic signals per minute at cross-clamp removal, 10.9 embolic signals per minute at partial occlusion clamp removal, and fewer than 3 embolic signals per minute at other times. Correlation was found between the number of emboli, severity of aortic atheromatosis, and neurocognitive deterioration. CONCLUSIONS: The majority of emboli detected during coronary artery bypass grafting are associated with the release of clamps. Clamp manipulation may lead to release of aortic atheromatous debris. These emboli may be relevant to neurocognitive outcome.