The impact of vessel clamps on endothelial integrity and function of saphenous vein grafts

Abstract

Background: Saphenous vein graft (SVG) failure can be associated with endothelial damage during coronary artery bypass grafting (CABG). Endothelial damage may develop after application of occlusive vessel clamps on SVGs. This study was designed to investigate the effect of plastic and metal clamps on the endothelial integrity and function of SVGs.

Methods: Saphenous vein samples were obtained from 10 consecutive patients, who underwent an elective CABG using SVG. Plastic (group 1) and metal (group 2) clamps were sequentially applied on the vein. Each set of clamps (1 plastic and 1 metal) was removed and sampled at 5, 15, and 30 min, respectively. A short SVG segment was removed as control. The samples were fixed for histopathologic study using hematoxylin eosin staining and immunostaining for endothelial nitric oxide synthase (eNOS) expression. In each group, endothelial, elastic tissue, muscular layer, and adventitial changes were investigated under light microscope and compared using a histologic scoring system. The intensity of eNOS expression was assessed using histochemical scoring system.

Results: In both groups, histopathologic examinations showed progressive endothelial damage in the zones of clamp application, compared with the control group (P < 0.001). Histopathologic changes were more favorable with the metal clamps, compared with the plastic clamps, at 5 and 15 min. No significant increase in endothelial damage occurred after 15 min. The eNOS immunoreactivity of SVGs significantly decreased in the damaged areas of the endothelium (P < 0.05). In metal clamps, the intensity of eNOS immunostaining was significantly high at 5 min, compared with plastic clamps (P < 0.05). However, the intensity of eNOS expression in metal clamps was significantly lower than plastic clamps at 15 min (P < 0.05). No significant difference was observed between the groups at 30 min.

Conclusions: The endothelial cells can be better preserved with short-term application of SVGs with metal clamps rather than plastic clamps. These findings suggest that temporary use of metal clamps can be preferred without major effects on vascular integrity and function.