Hemodynamic effects on atherosclerosis-prone coronary artery: Wall shear stress/rate distribution and impedance phase angle in coronary and aortic circulation

The objective of the present study was to evaluate the hemodynamic characte ristics of an atherosclerosis-prone coronary artery compared to the aorta. We describe three-dimensional spatial patterns of wall shear stress (WSS) a ccording to the impedance phase angle in pulsatile coronary and aorta model s using in vivo hemodynamic parameters and computed numerical simulations b oth qualitatively and quantitatively. Angiography of coronary arteries and aortas were done to obtain a standard model of vascular geometry. Simultane ously to the physiologic studies, flow-velocity and pressure profiles from in vivo data of the intravascular Doppler and pressure wire studies allowed us to include in vitro numerical simulations. Hemodynamic variables, such as flow-velocity, pressure and WSS in the coronary and aorta models were ca lculated taking into account the effects of vessel compliance and phase ang le between pressure and flow waveforms. We found that there were spatial fl uctuations of WSS and in the recirculation areas at the curved outer wall s urface of the coronary artery. The mean WSS of the calculated negative phas e angle increased in the coronary artery model over that in the aorta model and the phase angle effect was most prominent on the calculated amplitude of WSS of the coronary artery. This study suggests that the rheologic prope rty of coronary circulation, such as the fluctuation of WSS/WSR induces sev eral hemodynamic characteristics. A separation of flow-velocity, a differen ce in phase between pressure conductance and blood flow and prominent tempo ral and/or spatial oscillatory fluctuations of the shear forces as a functi on of pulsatile flow might be important factors in atherogenesis and progre ssion of atherosclerosis.