A computational fluid-structure interaction analysis of coronary Y-grafts

Coronary artery disease is one of the leading causes of death worldwide. The stenotic coronary vessels are generally treated with coronary artery bypass grafts (CABGs), which can be either arterial (internal mammary artery, radial artery) or venous (saphenous vein). However, the different mechanical properties of the graft can influence the outcome of the procedure in terms of risk of restenosis and subsequent graft failure. In this paper, we perform a computational fluid-structure interaction (FSI) analysis of patient specific multiple CABGs (Y-grafts) with the aim of better understanding the influence of the choice of bypass (arterial vs venous) on the risk of graft failure. Our results show that the use of a venous bypass results in a more disturbed flow field at the anastomosis and in higher stresses in the vessel wall with respect to the arterial one. This could explain the better long-term patency of the arterial bypasses experienced in the clinical practice. (C) 2017 IPEM. Published by Elsevier Ltd. All rights reserved

Computational study of the fluid-dynamics in carotids before and after endarterectomy

In this work, we provide a computational study of the effects of carotid endarterectomy (CEA) on the fluid-dynamics at internal carotid bifurcations. We perform numerical simulations in real geometries of the same patients before and after CEA, using patient-specific boundary data obtained by Echo-Color Doppler measurements. We analyze four patients with a primary closure and other four where a patch was used to close arteriotomies. The results show that (i) CEA is able to restore physiological fluid-dynamic conditions; (ii) among the post-operative cases, the presence of patch leads to local hemodynamic conditions which might imply a higher risk of restenosis in comparison with the cases without patch

Computational comparison between Newtonian and non-Newtonian blood rheologies in stenotic vessels

This work aims at investigating the influence of non-Newtonian blood rheology on the hemodynamics of 3D patient-specific stenotic vessels, by means of a comparison of some numerical results with the Newtonian case. In particular, we consider two carotid arteries with severe stenosis and a stenotic coronary artery treated with a bypass graft, in which we virtually vary the degree of stenosis.We perform unsteady numerical simulations based on the Finite Element method using the Carreau-Yasuda model to describe the non-Newtonian blood rheology. Our results show that velocity, vorticity and wall shear stress distributions are moderately influenced by the non-Newtonian model in case of stenotic carotid arteries. On the other hand, we observed that a non-Newtonian model seems to be important in case of stenotic coronary arteries, in particular to compute the relative residence time which is greatly affected by the rheological model