Experience of Patient-Specific CFD Simulation of Blood Flow in Proximal Anastomosis for Femoral-Popliteal Bypass

Abstract

Femoral artery bypass surgery needs postoperative monitoring due to the high complication risks after bypass. Numerical simulation is an effective tool to help solve this task. This work presents the experience of patient-specific CFD simulation of blood flow in proximal anastomosis for femoral-popliteal bypass, including patient follow-up after bypass surgery. Six cases of proximal anastomosis of femoral-popliteal bypass 3–30 months after surgery were studied. A repeated study was performed for four patients to monitor geometric and hemodynamic changes. The blood flow structure variety in proximal anastomoses and the blood flow dynamics during the cardiac cycle are described in detail using CFD simulation. Special attention is paid to time-average wall shear stresses (TAWSS) and oscillatory shear index (OSI) distributions. Low and oscillatory wall shear stresses were registered in the graft downstream from the suture, especially in case of low inlet flow. It was shown that the postoperative geometry changes led to significant hemodynamic changes; thereby, neointima has grown in areas with initially low and oscillatory wall shear stresses.

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].…”

Carotid Artery Bypass Surgery of In-Body Tissue Architecture-Induced Small-Diameter Biotube in a Goat Model: A Pilot Study

“…As mentioned above, external factors unrelated to the physical properties of Biotubes were considered because the stenosis of Biotubes occurred locally and was delayed. Simulations of saphenous vein graft stenosis after lower extremity bypass surgery using computational fluid dynamics [ 20 , 21 , 22 ] and a discussion of the angle and shape of the anastomosis [ 23 ] have been reported, and the phenomenon of IH in the vascular graft was discussed from a fluid dynamics perspective. Flow geometrical changes, stagnation, and turbulence are risks in the local graft area because bypass surgery is essentially an artificial blood flow design that differs from the line of a native artery.…”

“…Flow geometrical changes, stagnation, and turbulence are risks in the local graft area because bypass surgery is essentially an artificial blood flow design that differs from the line of a native artery. Wall shear stress (WSS), which is a hydrodynamic index, or time-averaged WSS, which excludes the effect of heart rate variability on WSS, has been associated with IH and discussed from a molecular biological perspective [ 20 , 22 , 24 ]. Furthermore, thrombus formation or IH development, from a molecular biological perspective, can be induced at sites of blood stagnation, where endothelial cell homeostasis is not maintained and macrophage engraftment is enhanced [ 17 ].…”