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.

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.

The paper presents the results of a numerical study of the flow in a symmetric model of a healthy popliteal venous valve with different leaflet elasticity. The focus is on the analysis of the stagnant area under the valve leaflet. The stagnant area under the valve leaflet, as well as behind the valve, is of great practical interest to phlebologists in terms of the possibility of blood clots. The flow in the constructed simplified model of the venous valve gave good qualitative agreement with the clinical ultrasound data for a leaflet with Young modulus of 1.2 MPa.

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The paper presents a comparative numerical study of pulsatory blood flow in five patient-specific models of femoral-popliteal artery anastomosis. Three-dimensional geometric models of a proximal junction of the common femoral artery/graft were constructed on the bases of CT angiography. The influence of junction geometry on the blood flow and wall shear stress is analyzed. The ratio of the measured CFA and graft diameters and the junction angle are considered as the major geometrical parameters. Numerically calculated velocity fields are analyzed, and stagnant zones in the anastomoses flow are identified. Time-averaged distributions of wall shear stress and oscillatory shear index obtained for five patient-specific model are compared.