Flow patterns through vascular graft models with and without cuffs.

Chia Min Leong,Gary B Nackman,Timothy Wei,Roi Gurka

doi:10.1371/journal.pone.0193304

Chia Min Leong, Gary B Nackman + Show 2 more

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https://doi.org/10.1371/journal.pone.0193304

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Abstract

The shape of a bypass graft plays an important role on its efficacy. Here, we investigated flow through two vascular graft designs–with and without cuff at the anastomosis. We conducted Digital Particle Image Velocimetry (DPIV) measurements to obtain the flow field information through these vascular grafts. Two pulsatile flow waveforms corresponding to cardiac cycles during the rest and the excitation states, with 10% and without retrograde flow out the proximal end of the native artery were examined. In the absence of retrograde flow, the straight end-to-side graft showed recirculation and stagnation regions that lasted throughout the full cardiac cycle with the stagnation region more pronounced in the excitation state. The contoured end-to-side graft had stagnation region that lasted only for a portion of the cardiac cycle and was less pronounced. With 10% retrograde flow, extended stagnation regions under both rest and excitation states for both bypass grafts were eliminated. Our results show that bypass graft designers need to consider both the type of flow waveform and presence of retrograde flow when sculpting an optimal bypass graft geometry.

Highlights

The efficacy of bypass grafts depends on its shape [1]
Due to altered hemodynamic conditions at the anastomosis, regions of high shear stress may occur and are known to cause cell damage [7] while regions of low shear stress would lead to intimal hyperplasia, characterized by the abnormal proliferation of smooth muscle cells [8,9,10,11,12,13]
We examined two pulsatile waveforms of rest and excitation states, with 10% and without retrograde flow for two different bypass graft models—a straight end-to-side and a contoured end-to-side

Summary

Introduction

The efficacy of bypass grafts depends on its shape [1]. Numerous bypass grafts with cuff and patch technologies at the anastomosis like Linton patch [2], Miller cuff [3], Tyrell vein collar [4] and Taylor patch [5] had been designed to satisfy this goal. Cuffs and patches could be harvested from autologous veins or pre-formed during the manufacturing of bypass grafts. These designs having different geometries and sizes at the anastomosis would have an implication on hemodynamics in that region. Maintaining the proper function of bypass grafts is strongly dependent on hemodynamics. Due to altered hemodynamic conditions at the anastomosis, regions of high shear stress may occur and are known to cause cell damage [7] while regions of low shear stress would lead to intimal hyperplasia, characterized by the abnormal proliferation of smooth muscle cells [8,9,10,11,12,13]

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