Mechanical aspects of vascular graft-host artery anastomoses

For vascular graft implantation the mechanical stresses induced by abnormal flow dynamics as well as regions of stress concentration in the walls of the host artery and the graft appear to play an important role in neo-intimal fibrous hyperplasia formation and loss of patency. Detailed in vitro and in vivo experimental studies as well as theoretical analysis, will help delineate the factors responsible for hyperplasia formation and thus enable modifications in the design characteristics to minimize the problem. In the case of end-to-end anastomoses the compliance mismatch between the host artery and the vascular graft appears to be the dominant factor for the abnormal flow dynamics in the anastomotic region. However, in end-to-side anastomoses, the geometry at the anastomosis appears to be more important, with the compliance mismatch playing a secondary role. Further detailed experimental studies complemented by detailed three-dimensional unsteady flow analysis in realistic anastomotic geometries are needed to suggest possible solutions to minimize the problem of loss of patency, particularly with medium and small diameter vascular grafts.<
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