Silent Cerebral Microembolism during Coronary Artery Bypass Graft Surgery

A 62 year-old man with known coronary artery disease underwent a three-vessel CABG after a positive exercise tolerance test revealed reversible ischemic changes. Transcranial Doppler ultrasonography (TCD) and transesophageal monitoring (TEE) were used intraoperatively for monitoring of highintensity transient signals (HITS), representing both gaseous and particulate cerebral emboli. Non-pulsatile flow was initially seen in the proximal middle cerebral arteries on TCD while the patient was on bypass (Video). Although the single aortic cross clamp technique was used to reduce aortic arch manipulation and release of solid microemboli from the aortic wall, release of the clamp allowed introduction of multiple gaseous microbubbles into the left ventricle and aorta as seen by TEE (Figure 1, Video). This shower of microbubbles was then detected in the proximal middle cerebral arteries as HITS by TCD monitoring (Figure 2, Video). Post-operatively, the patient did not demonstrate a detectable neurologic deficit.