A parametric study of the effect of arterial wall curvature on non-invasive assessment of stenosis severity: Computational fluid dynamics study

The effect of coronary arterial wall curvature on noninvasive assessment of stenosis severity was studied by examining the fractional flow reserve (FFR), pressure drop coefficient (CDP) and lesion flow coefficient (LFC) under different angles of curvature of the arterial wall models. Computational simulation of hyperemic blood flow in curved arteries with different angles of curvature (0°, 30°, 60°, 90° and 120°) was developed in three severe categories of stenosis of 70% (moderate), 80% (intermediate), and 90% (severe) area stenoses (AS) to evaluate the effect of curvature on FFR, CDP and LFC. The numerical study showed that for a given percentage of AS, the curvature of the arterial wall augmented the flow resistance in addition to the resistance caused by the stenosis. Also, there are significant differences in FFR, CDP and LFC between a straight and a curved section. With an increase in artery wall curvature from 0° to 120°, FFR significantly decreases by 5%, 8% and 20% in 70%, 80% and 90% AS respectively. For a fixed stenosis severity, CDP significantly increases, whereas LFC decreases as the angle of curvature changes from straight to curved section. We conclude that the significant differences in FFR, CDP and LFC confirms that the functional significance of stenosis assessed non-invasively could lead to misjudgment of its severity. This will notably influence the intermediate stenosis severity. So the arterial wall curvature should be considered when assessing the significance of stenosis as an alternative to FFR.