Computation of Hemodynamics in Tortuous Left Coronary Artery: A Morphological Parametric Study

Abstract

Coronary tortuosity (CT) would alter the local wall shear stress (WSS) and may become a risk factor for atherosclerosis. Here we performed a systematic computational study to relate CT morphological parameters to abnormal WSS, which is a predisposing factor to the formation of atherosclerotic lesions. Several idealized left coronary artery (LCA) models were created to conduct a series of morphological parametric studies, in which we concentrate on three specific morphological parameters, the center line radius (CLR), the bend angle (BA), and the length between two adjust bends (LBB). The time averaged WSS (TAWSS), the oscillatory shear index (OSI), and the time averaged WSS gradient (WSSGnd) were explored by using the computational fluid dynamics (CFD) method, in order to determine susceptible sites for the onset of early atherosclerosis. In addition, two realistic LCA models were reconstructed to further validate the finding's credibility. The CLR and LBB had great impact on the distributions of WSS-derived parameters, while the BA had minor impact on the hemodynamic of the tortuous arteries. Abnormal regions with low TAWSS (TAWSS < 0.5 Pa), high OSI (OSI > 0.1) and high WSSGnd (WSSGnd > 8) were observed at the inner wall of bend sections in the models with small CLR or small LBB. These findings were also confirmed in the realistic models. Severe CT with small CLR or LBB would lead to the formation of abnormal WSS regions at the bend sections and providing these regions with favorable conditions for the onset and/or progression of atherosclerosis.

Vascular Remodelling Relates to an Elevated Oscillatory Shear Index and Relative Residence Time in Spontaneously Hypertensive Rats

“…A decrease in the fluid-solid coupled interaction might explain the severely disturbed flow in the SHR-NIF group, which was consistent with previous findings of significantly increasing turbulent kinetic energy in an ideal rigid ascending aorta model 6 . These findings indicated that the decreased interaction in artery regions might contribute to spatial susceptibility to lesions formation in hypertensive and antihypertensive individuals regardless of the drop in BP, especially in arteries with high tortuosity or bifurcations 21 . Reducing this increased risk required interventions, drugs or exercise, to directly improve vascular remodelling.…”

Effects of severity and location of stenosis on the hemodynamics in human aorta and its branches

“…The TAWSS and the OSI are defined as where τ W is the WSS vector and T is the cardiac cycle. The OSI can reach a maximum value of 0.5 in regions with the high oscillating shear stress indicating the greater susceptibility of these regions to develop atherosclerosis [5,7,23,42]. Figure 3a, b demonstrates the WSS at the moments of late diastole and peak systole in the cardiac cycle over the endothelial surface of the healthy thoracic aorta.…”

“…However, the role of high wall shear stresses on the plaque rupture and atherothrombosis has been widely accepted [3,4,12,29]. Accurate knowledge of stresses developed in both healthy and diseased vessels is critical in analyzing biomechanical determinants of plaque rupture [3,29,42]. Therefore, we quantify the hemodynamics for moderate and severe stenosed aortic arch and its branches to demonstrate the impact of plaque location and size to the high stress magnitude.…”

Coronary tortuosity and its role in myocardial ischemia in patients with no coronary obstructions

“…These patients also had more angina crises (p < 0.05). 44 The only retrospective study on the theme was done by a Chinese team, and included 48 patients with angina chest pains who underwent myocardial scintigraphy and coronarography, and exclusion criteria included individuals with obstructive coronary disease, myocardial bridge, coronary spasm, coronary fistula, hypertrophic cardiomyopathy, myocarditis, and aortic stenosis.…”