Surgical sealant in the prevention of early vein graft injury in an ex vivo model

BACKGROUND: The amelioration of the adaptation process (arterialisation) of the vein graft wall to the arterial circulation in coronary artery bypass surgery by using extravascular support is clearly established in animal models and in in vitro and ex vivo set-ups. This support consists of some form of external graft-supporting modality like a prosthetic graft of stent. The clinical application of perivenous support, however, is hampered due to the fact that no easy applicable external support is available. Considering that application in the form of a spray is the most convenient modality, we evaluated whether polyethylene glycol is capable of providing adequate perivenous support. Polyethylene glycol is a synthetic, biodegradable product, used in cardiac surgery as a sealant, and is commercially available in the form of a spray.

METHODS: Segments of human saphenous vein graft obtained during coronary artery bypass graft (CABG) procedures were placed in an ex vivo model, a side loop of the extracorporeal perfusion circuit, and perfused with autologous blood, making the circumstances identical to the implanted saphenous vein grafts concerning pressure, temperature, level of complement and leukocyte activation and blood pressure. Alternately around every other study vein graft segment polyethylene glycol was applied. Unsupported grafts served as control. After 1 min of solidification, perfusion was started with a pressure of about 60 mmHg (nonpulsatile flow). Perfusion was maintained for 60 min, after which the grafts were collected for light microscopy and electron microscopy.

RESULTS: Light microscopy and electron microscopy showed remarkable attenuation of endothelial cell loss and less injury of smooth muscle cells of the circular and longitudinal layer of the media in the supported group compared to the nonsupported vein graft segments.

CONCLUSION: Polyethylene glycol is able to provide adequate external vein graft support, preventing overdistension, in an ex vivo model. This provides a basis for clinical application. Further investigation is warranted to evaluate long-term effects.