Effects of adventitial glutaraldehyde cross-linking on biomechanical properties of human saphenous vein graft

BACKGROUND: Poor venous wall is one of the inducing factors causing saphenous vein failure after coronary artery bypass grafting (CABG). OBJECTIVE: To explore the effects of adventitial glutaraldehyde cross-linking on the biomechanical properties of human saphenous vein graft (SVG). METHODS: Forty residual segments of SVG were collected from the patients undergoing CABG. Those segments were randomly divided into group A (n=20) and group B (n=20). Adventitial cross-linking was performed with 0.3% glutaraldehyde solution. Each SVG segment in group A was equally subdivided into two parts: one for adventitial cross-linking 5 minutes and the other as self-control. Each SVG segment in group B was also equally subdivided into two parts: one for adventitial cross-linking 10 minutes and the other as self-control. The ultra-structural changes of the venous wall with or without cross-linking were observed by fluorescence microscope and scanning electron microscope. The SVG segments in two groups underwent the uniaxial stretch test to detect the stress-strain relationship, Young’s elastic modulus and breaking strength of SVG segments receiving different processing. RESULTS AND CONCLUSION: (1) Fluorescence microscope: Compared with the SVGs of self-control, cross-linked SVGs mainly presented with compacted adventitial monomer of collagen and increased density of type I collagen, without obvious ultra-structural changes in the lumen surface. (2) Scanning electron microscope: The adventitial collagen fibers in the self-control segments showed a typical wavy loose arrangement, while the adventitial collagen fibers in the cross-linked segment appeared to have a dense fibrous network. (3) Uniaxial stretch test: Compared with the self-control parts, the stress-stretch ratio curve in the cross-linked parts in the two groups was shifted to the left remarkably, and in the high strain region (stretch ratio 1.3-1.5), the Young’s elastic modulus was also increased significantly (P < 0.05). Compared with the SVGs in the cross-linking 5 minutes, the stress-stretch ratio curve in the SVGs in the cross-linking 10 minutes was shifted to the left remarkably, and in the high strain region (stretch ratio 1.3-1.5), the Young’s elastic modulus was also increased significantly (P < 0.05). The breaking strength of cross-linked SVGs was higher than that of self-control SVGs in the two groups (P < 0.05). To conclude, adventitial glutaraldehyde cross-linking reinforces venous wall and reduces the ductility of human SVG.