EFFECTS OF SAND THERAPY ON FLUID DYNAMICS OF BLOOD IN THE POPLITEAL ARTERY BASED ON THE EULER MULTIPHASE MODEL

The effect of sand therapy on the hemodynamics of the popliteal artery (POA) was investigated to elucidate its mechanism in atherosclerosis physiotherapy. The hemodynamic parameters of the POA before and after sand therapy were obtained from 58 subjects and statistically analyzed. A three-dimensional finite element model of POA bifurcation was established. Blood was regarded as a triple-phase flow composed of plasma, red blood cells (RBCs), and white blood cells (WBCs). Using computational fluid dynamics (CFD), blood flow velocity, wall shear stress (WSS), and blood cell volume distribution before and after sand therapy were calculated. Sand therapy could reduce the vortex and reflux in blood vessels. The maximum increase in blood axial velocity was 34.38%. The maximum WSS increased by 22.82 Pa and the blood cells gradually moved away from the vessel wall and toward the axis of the blood vessel. The reduction in vortex and reflux, and the increase in blood axial velocity after sand therapy are beneficial in reducing the accumulation of cholesterol and other substances, thereby alleviating the formation of atherosclerotic plaques and lipid streaks. The rise in WSS slows the tendency of arterial vascular thickening in regions of low WSS. The movement of blood cells to the axis of blood vessels can reduce the possibility of thrombosis caused by blood cells squeezing on the blood vessel walls. These findings suggest that sand therapy may slow atherosclerosis progression.

A Fluid-Structure Interaction Study of Different Bicuspid Aortic Valve Phenotypes Throughout the Cardiac Cycle

The bicuspid aortic valve (BAV) is a congenital malformation of the aortic valve with a variety of structural features. The current research on BAV mainly focuses on the systolic phase, while ignoring the diastolic hemodynamic characteristics and valve mechanics. The purpose of this study is to compare the differences in hemodynamics and mechanical properties of BAV with different phenotypes throughout the cardiac cycle by means of numerical simulation. Based on physiological anatomy, we established an idealized tricuspid aortic valve (TAV) model and six phenotypes of BAV models (including Type 0 a-p, Type 0 lat, Type 1 L-R, Type 1 N-L, Type 1 R-N, and Type 2), and simulated the dynamic changes of the aortic valve during the cardiac cycle using the fluid-structure interaction method. The morphology of the leaflets, hemodynamic parameters, flow patterns, and strain were analyzed. Compared with TAV, the cardiac output and effective orifice area of different BAV phenotypes decreased certain degree, along with the peak velocity and mean pressure difference increased both. Among all BAV models, Type 2 exhibited the worst hemodynamic performance. During the systole, obvious asymmetric flow field was observed in BAV aorta, which was related to the orientation of BAV. Higher strain was generated in diastole for BAV models. The findings of this study suggests specific differences in the hemodynamic characteristics and valve mechanics of different BAV phenotypes, including different severity of stenosis, flow patterns, and leaflet strain, which may be critical for prediction of other subsequent aortic diseases and differential treatment strategy for certain BAV phenotype.