The Interaction of different mechanical forces on atherosclerotic plaques in coronary lesions with differing degrees of eccentricity

Background: Wall shear stress (WSS) and pressure drop (PD) within coronary atherosclerotic lesions may contribute to plaque rupture. The relationship between these mechanical forces and lesion eccentricity throughout the cardiac cycle is unclear. Methods: Three-dimensional models of human coronary arteries were reconstructed from the coronary angiograms of four subjects. These arteries exhibited similar morphology, dimensions and lesion severity but each had a different stenosis eccentricity index (EI). Both WSS and PD were calculated throughout the cardiac cycle using computational fluid dynamics (CFD) and compared between patients to understand the effects of lesion eccentricity. To verify the CFD results, in vitro particle image velocimetry (PIV) was performed using pulsatile flow and two artificial models corresponding to the dimensions of the coronary arteries but representing extremes of lesion eccentricity. Results: On CFD analysis, both WSS and PD values were higher in more eccentric coronary lesions throughout cardiac cycle (WSS\PD values throughout the cardiac cycle of 46–109 Pa\2985–7891 Pa, 132–223 Pa\3377–8075 Pa, 200–560 Pa\3827–8295 Pa and 376–609 Pa\4276–8504 Pa for arteries with EI of 0.05, 0.64, 0.75 and 0.97, respectively; both P values <0.0001). Large variations were seen in PD throughout the cardiac cycle, while WSS did not vary significantly. PIV confirmed that higher WSS and PD values were observed in the eccentric model compared to the concentric model (WSS\PD values of 14–82 Pa\175}–6847 Pa and 5–44 Pa\50–2351 Pa for EI of 1 and 0, respectively; P <0.01 and P = 0.03). Conclusion: Our results demonstrate that lesion eccentricity in human coronary arteries affects mechanical forces throughout cardiac cycle.