Journal
MEDICAL ENGINEERING & PHYSICS
Volume 25, Issue 10, Pages 843-858Publisher
ELSEVIER SCI LTD
DOI: 10.1016/S1350-4533(03)00124-3
Keywords
particle-hemodynamics; hemodynamic wall parameters; near-wall residence time; femoropopliteal bypass; end-to-side anastomosis; intimal hyperplasia
Categories
Funding
- NHLBI NIH HHS [R1HL41372-06A3] Funding Source: Medline
- NATIONAL HEART, LUNG, AND BLOOD INSTITUTE [R29HL041372, R01HL041372] Funding Source: NIH RePORTER
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Late-stage occlusions of peripheral synthetic bypass grafts are frequently due to intimal hyperplasia and/or thrombosis at the distal anastomosis, resulting in unacceptably high failure rates. It has been widely established that hemodynamic and blood particle interactions with the vascular surface as well as surgical injury and compliance mismatch are inciting mechanisms capable of eliciting various cellular level responses associated with distal anastomotic intimal hyperplasia (IH) formation. Primary geometric factors influencing anastomotic hemodynamics include the graft-to-artery diameter ratio and graft-hood shape, which are determined by the graft caliber and initial graft-end cut selected by the vascular surgeon. In this study, the particle-hemodynamic effects of graft-end cuts (straight, curved, and S-shaped) and graft-to-artery diameter ratios (2:1 vs. 1.5:1) have been numerically assessed in four common unexpanded anastomotic configurations with respect to vortical flow patterns, wall shear stress based parameters, and platelet interactions with the vascular surface. Sites of significant platelet-wall interactions have been identified by a novel nearwall residence time (NWRT) model, which includes shear stress based factors for platelet activation and endothelial cell expression of anti-thrombogenic compounds. Of the configurations evaluated, straight and curved graft-end cuts with a graft-to-artery diameter ratio of 1.5:1 were found to reduce the particle-hemodynamic potential for IH development at locations critical to flow delivery. Nevertheless, the potential for significant IH occurrence via platelet and/or endothelial response pathways was highly evident in all conventional anastomoses considered, such that a decisively superior configuration was not determined. These results illustrate the need for alternative anastomotic designs with the intent of reducing critical hemodynamic wall parameters and mitigating regions of significant particle-wall interactions. (C) 2003 IPEM. Published by Elsevier Ltd. All rights reserved.
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