Graft atheroembolism as the probable cause of failure to wean from cardiopulmonary bypass

Experimental coronary artery occlusion: relevance to off-pump cardiac surgery

Mechanical coronary artery occlusion is required for minimally invasive direct coronary artery bypass and off-pump coronary artery bypass surgery. It is important that the method of occlusion be minimally traumatic. Chronic effects of these methods have never been studied. Temporary occlusion of coronaries utilizing suture snare, silastic loop snare, and bulldog clamp was carried out in 12 Yucatan pigs. Three animals each were sacrificed acutely and at 3, 6, and 12 months. The area of occlusion of each vessel was examined by light microscopy and the degree of damage recorded. In the animals sacrificed acutely, there was more damage using the suture snare than with the other 2 methods, but there was minimal damage at longer intervals. There was slight damage acutely and chronically with the bulldog technique. No damage was seen acutely with the silastic loop technique, but some late damage was found. The techniques of coronary artery dissection and occlusion used for minimally invasive and off-pump bypass surgery may contribute to early postoperative graft occlusion.

Safe and effective method of stabilization for coronary artery bypass grafting on the beating heart

BACKGROUND

There is an emerging interest in performing coronary artery bypass grafting on the beating heart. This study examines the efficacy and safety of two types of coronary artery stabilizers developed to perform coronary artery bypass grafting on the beating heart.

METHODS

Four dogs underwent left internal mammary artery to left anterior descending artery anastomosis using a retractor-fixed stabilizer. Measurements of hemodynamic indices and range of motion of the targeted arteriotomy were done before and after application of the stabilizers. Patency of the anastomosis was evaluated by angiography. To clinically validate the safety of this stabilizer, we collected data on 150 patients from centers that had access to the retractor-fixed stabilizer.

RESULTS

All animals survived the procedure with no ischemic changes or hemodynamic alterations. A significant reduction in range of motion (mm) of the left anterior descending coronary artery was achieved after application of the stabilizers. Angiographic studies showed good anastomotic patency. Histologic examination showed no myocardial injury. Patient data revealed successful completion of the anastomosis, with conversion to sternotomy or cardiopulmonary bypass in 1 patient each. Intraoperative and postoperative myocardial infarctions occurred in 1 patient each, with one in-hospital death.

CONCLUSIONS

Significant stabilization of targeted coronary arteries allowing the performance of safe and reliable anastomosis on a beating heart can be achieved using the stabilizer.

Myocardial injury during reoperation for coronary artery bypass surgery

OBJECTIVES

To determine the incidence, triggers, and timing of myocardial injury during reoperation for coronary artery bypass surgery.

DESIGN

Prospective observational.

SETTING

One tertiary care university hospital.

PARTICIPANTS

15 patients undergoing reoperation.

INTERVENTIONS

Multilead electrocardiographic monitoring approximately every 3 minutes during surgery.

MEASUREMENTS AND MAIN RESULTS

The occurrence of a new ischemic ST elevation or depression on the electrocardiogram (ECG) was determined. A major deterioration in ventricular function after cardiopulmonary bypass (CPB) also was determined. Peak creatine kinase myocardial band (CK-MB) > or = 25 IU/L was considered to be the marker of myocardial injury. Seven patients demonstrated myocardial injury, all intraoperatively. Five of these patients had new ST elevation episodes before CPB. Three of the episodes were temporally associated with an abrupt increase in the heart rate. The other two episodes were temporally associated with surgical manipulation of the heart and the old grafts. The sixth patient had a significant deterioration of ventricular function during CPB. One of the patients who had ST elevation before CPB and the seventh patient developed ST elevation towards the end of protamine administration.

CONCLUSIONS

In patients undergoing reoperation, the intraoperative incidence of myocardial injury, especially before CPB, was found to be substantially higher than that previously reported.