Effect of aortic spiral blood flow on wall shear stress in stenosed left main coronary arteries with varying take-off angle, stenosis severity and eccentricity

It is well accepted that blood flow in the human aorta is spiral by nature, with beneficial impacts for the cardiovascular system in the form of improved haemodynamics and efficient perfusion. This study investigates the effect of aortic spiral blood flow on wall shear stress (WSS) in computer-generated models of the left main trunk (LMT), also known as left main coronary artery, with varying take-off angle, stenosis severity and eccentricity. The results show that the spirality effect causes a substantial reduction in maximum WSS (WSS_max), average WSS (WSS_ave) and size of regions with low WSS. The effects of spiral flow on WSS_max become more significant with increasing LMT take-off angle and stenosis eccentricity, and they become less significant with increasing stenosis severity. The aortic spiral blood flow intensity, LMT take-off angle, stenosis severity and eccentricity statistically significantly predict the WSS; however, the strongest predictor of WSS is stenosis severity (F(4, 399) = 3653.85, p < 0.001 for WSS_max and F(4, 399) = 913.46, p < 0.001 for WSS_ave), followed by LMT take-off angle (F(4, 399) = 582.735, p < 0.001 for WSS_max and F(4, 399) = 163.16, p < 0.001 for WSS_ave), stenosis eccentricity (F(4, 399) = 230.15, p < 0.001 for WSS_max and F(4, 399) = 52.94, p < 0.001 for WSS_ave) and blood flow spirality (F(4, 399) = 112.37, p < 0.001 for WSS_max and F(4, 399) = 32.18, p < 0.001 for WSS_ave). Our findings suggest that naturally or artificially induced spiral flow in the aorta potentially has atheroprotective effects in the LMT.