Study of the blood flow structure in personalized models of graft branch from the femoral artery

The paper presents the methodology and results of calculating the pulsating flow of blood-mimicking fluid in three personalized models of proximal anastomosis of the femoral artery after femoral popliteal bypass surgery performed using synthetic grafts. Personalized models were built based on computed tomography data and ultrasound measurements of blood flow velocity in the common femoral artery and in the graft. The characteristics of the pulsating flow of blood-mimicking fluid were calculated by numerically solving the three-dimensional unsteady Navier-Stokes equations. Comparison of the calculated velocity field obtained for one of the personalized models with clinical measurement data using ultrasonic high-speed vector imaging (applying the V Flow technology implemented in the Mindray scanner) showed satisfactory agreement of the results. A comparative analysis of the flow structure in two personalized models built for the second patient one and seven months after surgery is given. It was established that the narrowing of the flow sections of the vascular bed, detected after seven months, due to the growth of neointima in the common femoral artery (immediately before the anastomosis) and in the initial section of the graft, led to a significant increase in gradients of the velocity field and the time-averaged wall shear stress ( TAWSS ) in the area of the anastomosis; at the same time, the value of the oscillatory shear index ( OSI ) on the wall throughout the entire anastomosis area decreased. It was also revealed that at a distance of several calibers from the anastomosis, a single-vortex, weakly swirling flow is formed in the graft, the direction of swirl in which is determined by the individual geometry of the anastomosis area.