Geometrical effects in the hemodynamics of stenotic and non-stenotic left coronary arteries-numerical and in vitro approaches.

Atherosclerosis is a common cardiovascular disease found in the left coronary artery (LCA), closely linked to local hemodynamic, which, in turn, is highly influenced by the artery geometry. The hemodynamics in the LCA was studied in a patient-specific geometry without any sign of disease using both numerical and in vitro approaches. The influence of non-planarity was evaluated through two models of the patient-specific LCA that deviate from its original geometry in their planarity. Afterwards, in all models, irregular stenoses were created by a procedure in which the stenosis emerges by diffusion from low wall shear stress (WSS) areas. The WSS distribution and flow patterns were evaluated in all the models. The experimental results validate the numerical code developed to study the blood flow assuming a steady state Newtonian behavior. Comparison between the planar and non-planar idealized LCA revealed no significant differences in low WSS regions forming stenotic regions with identical shape. In the patient-specific LCA, the low WSS regions are not consistent with the idealized models leading to a different stenosis shape. The results revealed that the non-planarity has an unquestionable effect in helicity. It was also demonstrated that eccentricity of the vessels cross section and the position of the apex in relation to the axis of the parent branch contribute to the flow patterns observed. Numerical results of pulsatile blood flow assuming a non-Newtonian behavior, in the patient-specific LCA, reinforce the non-planarity effect in local hemodynamics.