|Abstract:|| Coronary artery disease, which is one of the leading causes of death in the world, is caused by the build-up of atherosclerotic plaques in the vessel walls. The result is a reduction of oxygen supply to the heart, which increases the risk of myocardial infarction, stroke and unstable angina. For high-risk patients, coronary artery bypass graft (CABG) is the preferred treatment. In particular, the gold standard procedure for the surgical treatment
of the left anterior descending (LAD) coronary artery disease is the left internal mammary artery (LIMA) bypass. However, despite its excellent patency rates, LIMA bypass may fail due to restenosis. Specifically, the long-term patency of LIMA is thought to be related to the degree of stenosis in the native vessel.
In this context, we present a computational study of the fluid-dynamics in patient-specific geometries with the aim of investigating a possible relationship between coronary stenosis and LIMA graft failure. Firstly, we propose a strategy to prescribe realistic boundary conditions in absence of measured data, based on an extension of the well–known Murray's law to provide the flow division at bifurcations in case of stenotic vessels and non-Newtonian blood rheology. With the aim of investigating the actual influence of non-Newtonian blood rheology on the hemodynamics of 3D patient-specific stenotic vessels, we also show some results regarding the comparison between Newtonian and non-Newtonian rheology. Then,
we show the results regarding numerical simulations in patients treated with grafts in which the degree of coronary stenosis is virtually varied, in order to compare the fluid-dynamics in terms of hemodynamic indices potentially involved in restenosis development. Finally, we present some preliminary results concerning fluid-structure interaction simulations in CABGs with the aim of better understanding the influence of the bypass mechanical properties on the risk of graft failure.