Patient-specific simulation of the blood flow in a proximal femoral artery-graft junction

Abstract

The paper presents a computational procedure developed for patient-specified blood flow simulation in the proximal anastomosis of femoral-popliteal bypass. The calculations are based on a three-dimensional geometric model constructed from a CT angiography scan of the vascular bed in the anastomotic region and boundary conditions obtained by ultrasound Doppler measurements of the velocity in control sections of the bed. A numerical analysis of 3D pulsating flow structure in a particular model of the proximal anastomosis has been carried out. The model includes sections of the common femoral artery (CFA), the graft, the deep femoral artery and the superficial femoral artery. The Reynolds number based on the CFA inner diameter and the inlet bulk velocity is 880. The sizes and location of stagnant zones, areas with low values of the time-averaged wall shear stress modulus and with high values of the oscillatory shear index are determined. It is shown that the results of the prediction of areas with low values of the time-averaged shear stress modulus are in qualitative agreement with the data of local measurements of neointima thickness formed along the graft wall one year after the operation.

V Flow Measurements of Pulsatile Flow in Femoral-Popliteal Bypass Proximal Anastomosis Compared with CFD Simulation

“…It is also remarkable that the instant cross-flow pattern predicted by CFD for the chosen section (Figure 12d) looks like a vortex pair, but the direction of its circulation is opposite compared to that illustrated for the instant of the maximum flow in the anastomosis average model (Figure 3). Our experience in the parametric numerical simulation of pulsatile blood flow in different proximal anastomosis models, presented partially in [15][16][17], allows us to conclude that the circulation direction in the formed vortex pair depends not only on the examined phase of the cycle but also on the graft-to-CFA flow rate ratio and the individual geometry. The profiles of the streamwise velocity, V s , measured and calculated for a graft section, are shown in Figure 12c (here, the experimental profile is a result of phase-averaging over five cycles of blood flow recorded in vivo).…”

“…The computational grid generated for the personalized model consisted of 2 million elements. Using the procedures described in our previous reports [15][16][17], a personalized geometric model of the proximal anastomosis area of the patient, for whom an examination was carried out in the University clinic 7 months after the operation, was built based on data of MSCT angiography. This personalized model is illustrated in Figure 6a.…”

“…Ultrasound (US) methods for blood flow analysis are used mainly in clinical studies [13]. To obtain knowledge that is useful for the early prediction of dangerous postoperative complications, numerical calculations are performed for personalized anastomosis models based on magnetic resonance imaging (MRI) [14], US and multispiral computed tomography (MSCT) data [15][16][17].…”