ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

FLUID–STRUCTURE INTERACTION ANALYSIS OF A COUPLED
SEQUENTIAL CORONARY ARTERIAL BYPASS GRAFT
1. ABSTRACT
F. Kabinejadian 1 , D.N. Ghista 2 and H.L. Leo 3
The present study investigates the effects of wall compliance and non-Newtonian
rheology on the local flow field and hemodynamic parameters distribution in a coronary
arterial bypass coupled sequential anastomoses graft design, and verifies the advantages
of this design over the conventional end-to-side configuration. For this purpose, a twoway
fluid–structure interaction analysis has been carried out. A finite volume method is
applied to solve the three-dimensional, time-dependent, laminar flow of the
incompressible, non-Newtonian fluid; the vessel wall is modeled as a linearly elastic,
geometrically non-linear shell structure. In an iteratively coupled approach, the transient
shell equations and the governing fluid equations are solved numerically. The
simulation results indicate a diameter variation ratio of up to 4% and 5% in the graft and
the coronary artery, respectively. The wall compliance reduces the time-averaged wall
shear stress (TAWSS) up to 32% and somewhat increases the oscillatory nature of the
flow. In spite of the modest influence of wall compliance and non-Newtonian rheology
on the hemodynamic parameters distribution, the inclusion of these properties has
unveiled further advantages of the coupled sequential anastomoses model over the
conventional end-to-side anastomosis which had not been revealed in our previous
studies with the rigid-wall and Newtonian fluid models. Hence, the inclusion of wall
compliance and non-Newtonian rheology in flow simulation of blood vessels can be
essential in quantitative and comparative investigations.
2. INTRODUCTION
Hemodynamic pulsatile shear stress parameters are widely believed to be a highly
important factor in coronary arterial bypass grafts (CABGs), implicated in the formation
and progression of intimal hyperplasia (IH), the major cause of graft failure [1-5]. We
have designed a new CABG coupled-sequential anastomosis (SQA) configuration [6],
and have shown that it provides: (i) a more uniform and smooth flow at the end-to-side
(ETS) anastomosis, without impingement of blood flow on the artery bed and vortex
formation in the heel region of the ETS anastomosis within the coronary artery; (ii)
improved distribution of hemodynamic parameters (HPs) at the coronary artery bed and
in the heel region of the ETS anastomosis, with more moderate shear stress indices; and
(iii) a spare route for the blood flow to the coronary artery, to avoid re-operation in case
1
Post-Doctoral Research Fellow, Department of Bioengineering, National University of Singapore, 9
Engineering Drive 1, Block EA #03-12, Singapore 117576
2
Professor, Graduate Education (College Center), Framingham State University, Framingham, MA
01701-1901
3
Professor, Department of Bioengineering, National University of Singapore, 9 Engineering Drive 1,
Block EA #03-12, Singapore 117576