Arterial wall damage caused by snaring of the coronary arteries during off-pump revascularization

Anastomosis of a saphenous or mammary artery conduit to the coronary artery requires precise and reproducible microsurgical technique. Over the past 3 decades, the elective induction of cardiac arrest and circulatory support have provided the conditions suitable for microsurgical anastomosis to all coronary vessels. Beating heart coronary grafting was rejuvenated at our center in 1985 as an alternative to cardiopulmonary bypass and cardioplegic arrest. One of the requirements for off-pump grafting is local vascular control of the target vessel and prevention of bleeding into the field from the open coronary artery. The most common hemostasis technique in use today is the application of circumferential traction sutures and snares around the coronary artery. We performed a human cadaver study to evaluate the potential for local trauma to the native coronary artery caused by this method of hemostasis.

Our research team applied both 5-0 polypropylene and 2-0 polyester snares to the proximal and distal right coronary artery (RCA) and left anterior descending (LAD) in 25 isolated fresh human cadaver hearts. A total of 100 points of snare application to the native coronary vessels were induced and then investigated histologically, with hematoxylin-eosin, Weigert, and phosphotungstic hematoxylin staining.

The results suggested a direct relationship between the severity of the arterial lesion induced by the snares and the degree of local atherosclerotic disease in the native coronary artery. Compression and buckling of the elastic lamellae with medial fractures (similar in nature to angioplasty but directed inward) were seen when snares were applied to a region with marked atherosclerotic disease.

The application of snares to the coronary artery proximal and distal to the anastomotic site must be done with caution. In cases of marked atherosclerotic disease in the underlying coronary artery, a new intimal-medial lesion can occur with indiscriminate application of a tourniquet. This phenomenon may account for some of the reported cases of late peri-anastomotic or distal stenoses seen with off-pump coronary artery bypass grafting and significantly detract from the advantages offered by beating heart surgery. If one or both snares can be avoided entirely, or applied carefully to disease-free segments of the vessel, this problem may be avoided entirely.