Human heart model with Coronary Bypass Vessels. Use the bypass tubing to instantly install single, double, or triple bypasses in the heart, representing grafts of the saphenous vein of the lower leg, to connect the ascending aorta to the coronary arteries. Or in place of one of the vein grafts, connect the left internal mammary artery to the left anterior descending coronary artery (LIMA bypass) in the heart. Even with bypass vessels installed, you have full internal access to all four heart chambers and the mitral and tricuspid valves, by means of exclusive flip-open hinged access portals. This heart model is unique way to study the human circulatory system and anatomy of the human heart.