Detection of aortic emboli by transesophageal echocardiography during coronary artery bypass surgery.

OBJECTIVE

The purpose of this study was to determine whether emboli can be detected within the aortic lumen in patients undergoing coronary artery bypass surgery (CABG) and to relate the appearance of emboli to specific operative events.

DESIGN

Twenty patients were prospectively studied intra-operatively.

SETTING

Subjects were inpatients in an academic medical center.

PARTICIPANTS

All participants were scheduled for elective, isolated CABG.

INTERVENTIONS

Patients were continuously monitored using transesophageal echocardiography (TEE) from aortic cannulation to bypass discontinuation. After completion of the aortic examination, the probe was focused at the level of the aortic arch, just before the takeoff of the left subclavian artery. Emboli were defined as echogenic intraluminal signals not present in the same position on consecutive cross-sectional frames.

RESULTS

Intraluminal emboli were detected in all subjects, with a mean number of 535 and range of 8 to 1,885. Embolization was unevenly distributed through the procedure. A mean of 224 (42%) of 535 were detected within 4 minutes of aortic cross-clamp release and another 140 (24%) appeared after partial occlusion clamp release. Together, clamp placement and release represented 84% of all emboli. Emboli detected after clamp release were large, echodense particles easily distinguishable from the small, indistinct, poorly echogenic signals observed at bypass initiation.

CONCLUSIONS

Emboli can be visualized within the aortic lumen during CABG. Confirming previous reports, the majority of emboli detected are related to manipulation of aortic clamps. The composition and clinical significance of embolic material are unclear. The value of intraoperative TEE monitoring in predicting neurologic outcome remains to be determined.