TIME: Monday, February 13, 2012, 2:00 p.m.
Currently, the most effective therapy in treating multi-vessel occlusive coronary artery disease is bypass grafting with autologous vessels. The saphenous vein is the most widely used conduit for this purpose. Despite being the preferred treatment, venous grafts suffer high failure rates and require repeated revascularizations. Given the increasing number of bypass procedures performed each year, there is a critical need to extend the lifetime of vein grafts. It is generally agreed that vein grafts fail primarily due to intimal injury sustained from the acute pressure ramp when exposed to arterial conditions. External vein sheathing has been shown in many pre-clinical studies to be very effective in preventing overdistention and reducing long-term intimal hyperplasia. However, there is a lack of understanding in the optimal constriction of the sheath. We believe the key to maintaining long-term patency is to equilibrate the mean and local stresses as well as the diameter between the artery and vein graft. The goal of this study is to tune the mechanical environment of the vein graft to that of the coronary artery utilizing a novel external vein sheath and an unparalleled understanding of the mechanical properties of the coronary artery. We rely heavily on mathematical and finite elasticity theories to develop a multi-faceted mechanical framework that takes into consideration the effects of perivascular support and novel residual deformations. This culminates in the development of a microstructurally motivated constitutive model for understanding the mechanical environment of the coronary artery. We then develop a novel acellular conduit along with methods to match the mechanical environments between the vein graft and coronary artery.