Stroke Study: Operative Strategies to Reduce Cerebral Embolic Events During Coronary Artery Bypass Surgery

One of the most devastating complications of coronary artery bypass surgery (CABG) is
postoperative stroke. While the etiology of stroke after CABG is multifactorial,
atheroemboli generated during aortic manipulation is believed to account for most cerebral
embolic events. Manipulation of the aorta during CABG occurs during aortic cannulation,
institution and maintenance of cardiopulmonary bypass, and during aortic clamping and
unclamping with either a cross-clamp, partial-occluding clamp, or both. One operative
strategy to minimize aortic manipulation is to avoid cardiopulmonary bypass altogether by
using off-pump techniques (OPCAB). Another method is to avoid the use of aortic clamps and
to construct proximal aortocoronary anastomoses with facilitating devices that do not
require aortic clamping. The effect of these strategies on reducing cerebral embolic events
and the underlying mechanism for this reduction are not well-defined.

This study will test the hypothesis that an off-pump (OPCAB) approach and facilitating
devices to perform clampless proximal anastomoses will result in the least amount of aortic
manipulation and therefore the lowest incidence and frequency of cerebral embolic events.
The approach associated with the lowest incidence of TCD-detected cerebral embolic events
will also result in the lowest incidence and severity of postoperative neurocognitive
decline. Transcranial Doppler ultrasonography is an established method to detect cerebral
embolic signals during cardiac surgery and will be utilized to detect cerebral embolic
events during the operation. After an on- or off-pump strategy is selected, patients will be
subsequently randomized to one of two clamping strategies. There will be 4 groups of
patients: 1) OPCAB patients randomized to no clamping (facilitating device); 2) OPCAB
patients randomized to partial clamping; 3) on-pump patients randomized to double clamping;
and 4) on-pump patients randomized to a single clamp strategy.

Inclusion Criteria:

- > 18 years

- undergoing primary isolated coronary artery bypass surgery

- ability to sign informed consent

Exclusion Criteria:

- history of preoperative stroke

- reoperative cardiac surgery

- salvage or emergency CABG

- known left ventricular or left atrial thrombus

- concomitant valvular or aortic surgery