The harvesting technique affects the production of nitric oxide and endothelin in the internal thoracic artery graft.

Abstract

To assess the production of nitric oxide and endothelin in off-pump coronary artery bypass grafting by comparing 2 techniques of internal thoracic artery preparation: skeletonized and pedicled without endothoracic fascia. In this prospective, randomized clinical study, 40 patients undergoing off-pump coronary artery bypass grafting were randomized according to internal thoracic artery preparation technique into the skeletonized or pedicled (without endothoracic fascia) groups (n = 20 each). Endothelial expression of CD31 was evaluated by means of immunohistochemistry and en face immunofluorescence. Nitric oxide and cyclic guanosine monophosphate levels in internal thoracic artery plasma, as well as cyclic guanosine monophosphate and endothelin-1 levels in unused internal thoracic artery segments, were measured using enzyme-linked immunosorbent assays. Endothelin-1 mRNA expression was assessed by in situ hybridization. Skeletonized internal thoracic artery showed areas of poor endothelial continuity, whereas the pedicled internal thoracic artery without endothoracic fascia retained a uniform endothelium on immunostaining. This injury was accompanied by the absence of endothelial nitric oxide synthase immunostaining at regions of endothelial denudation. Plasma nitric oxide concentration was significantly lower, and endothelin-1 release from tissue extracts significantly greater, in skeletonized internal thoracic artery compared with pedicled internal thoracic artery without endothoracic fascia. In situ hybridization assay showed that endothelin-1 (EDN1) mRNA expression is upregulated in endothelial cells remaining in skeletonized internal thoracic artery. Reduced nitric oxide release and increased endothelin-1 release was observed in skeletonized internal thoracic artery compared with atraumatically prepared pedicled internal thoracic artery without endothoracic fascia. These observations may influence graft performance.