PRELIMINARY-ANALYSIS OF THE EFFECTS OF BLOOD-VESSEL MOVEMENT ON BLOOD-FLOW PATTERNS IN THE CORONARY-ARTERIES

Blood flow patterns are believed to be involved in the formation and p rogression of arterial diseases. If is possible that the normal physio logic movement of brood vessels during the cardiac cycle affects blood flow patterns significantly. For example, the contraction of the hear t in systole and subsequent relaxation in diastole create movements of the coronary arteries, as evidenced in real-time angiography. The eff ects of this movement on coronary artery flow patterns have never been previously analyzed. This work was undertaken to provide a preliminar y estimate of the importance of the effects of such physiologic moveme nts on blood flow patterns in the coronary arteries. A Womersley-type solution was used to determine the effect of axial movement on the wal l shear rate in a simplified model of the coronary arteries. The pulsa tile pressure gradient was derived from previously published coronary artery flow waveforms. The axial movement function was obtained from a three-dimensional reconstruction of a biplanar coronary angiogram. Si gnificant changes in wall shear rate were noted when the movement was taken into account. The maximum and minimum wall shear rates were 10 p ercent smaller and 107 percent larger in magnitude respectively, and t he Oscillatory Shear Index (OSI) was doubled. Most of the changes in w all shear rate were observed in systole, when the pressure gradient is minimal and the movement is strongest. The results indicate that bloo d vessel movement during the cardiac cycle has a significant effect on hemodynamic phenomena which have been associated with the development of atherosclerosis.