Hemodynamic Design of Coronary Artery Bypass Graft

Coronary artery bypass graft (CABG) is an open-chest surgical procedure whereby a healthy artery or vein (i.e., graft) is used to bypass an occluded coronary artery. The proximal portion of the graft is connected (or sutured) to the source of blood, and the distal portion is sutured distal to the occlusion to allow blood flow to bypass the atherosclerotic blockage and perfuse the myocardium. The first CABG procedure was performed by Rene Favaloro in 1967 at the Cleveland Clinic. The simultaneous presence of Rene Favaloro and Mason Sones (discovered coronary angiography in 1958) at the Cleveland Clinic in the 1960s truly revolutionized diagnosis (coronary angiography) and treatment (CABG) of coronary artery disease. Since then, CABG has evolved as one of the most common and effective primary surgical treatments for ischemic heart disease since its inception in the 1960s. Despite its widespread use, however, the outcome is not completely satisfactory. Mechanobiology has advanced substantially in the past several decades which can provide important guidelines for improving the outcome of CABG. For example, it has become clear that the mechanical stresses and strains in the cardiovascular system are under strict regulation, i.e., a homeostatic range of mechanical stresses and strains exists in the cardiovascular system, as outlined in Chap. 1 . A perturbation of the mechanical loading (change in blood pressure or flow) leads to adaptive biochemical and biological responses that restore mechanical homeostasis. In this sense, stenosis and failure of a graft may be viewed as an adaptation process gone awry.