Blood flow through a stenosed left anterior descending coronary artery: Evaluation of loss coefficients in one-dimensional fluid-structure interaction model

Coronary arterial flow is affected by conditions such as atherosclerosis and stenosis resulting in coronary artery disease. Quantifying the flow fields across arteries is a key aspect in the functional assessment of occlusive arterial disease. An essential aspect of blood flow modeling is the mechanical interaction between the fluid flow and the arterial vessel wall. The present study focuses on the modeling of blood flow within the left anterior descending artery affected with stenosis. A one-dimensional (1D) model was developed to study the transient blood flow characteristics in the artery. The 1D model is coupled with the material tube law to account for the flexibility of the arterial wall. The loss coefficients that account for the local viscous and turbulent losses across the stenosis region are estimated accurately in terms of the varying local cross-sectional area, instead of empirical constants used in the literature. It was observed that the magnitude of viscous losses decreases with an increase in the severity of stenosis. For lower degree of stenosis (<30%), the local turbulent losses are insignificant compared to the viscous losses. The maximum deformation of the vessel wall is similar to 0.12mm at t=0.45s for s=70%. During the cardiac cycle (T=0.9s), the artery is observed to be experiencing dilation (Delta r>0) in the upstream region, whereas contraction (Delta r<0) in the downstream region for all the values of severity (s). A fractional flow reserve of 58.53% was noticed in a stenosed artery of 70% severity.