Transient numerical simulation of the right coronary artery originating from the left sinus and the effect of its acute take-off angle on hemodynamics

Background: An anomalous origin of the right coronary artery from the left coronary artery sinus is usually characterized by an acute take-off angle. Most affected patients have no clinical symptoms; however, some patients have decreased blood flow into the right coronary artery during exercise, which can lead to symptoms such as myocardial ischemia. Most researchers who have studied an anomalous origin of the right coronary artery from the left coronary artery sinus have done so through clinical cases. In this study, we used numerical simulation to evaluate the hemodynamics of this condition and the effect of an acute take-off angle on hemodynamic parameters. We expect that the results of this study will help in further understanding the clinical symptoms of this anomaly and the hemodynamic impact of an acute take-off angle. Methods: Three-dimensional models were reconstructed based on the computed tomography images from 16 patients with a normal right coronary artery and 26 patients with an anomalous origin of the right coronary artery from the left coronary artery sinus. A numerical simulation of a two-way fluid-structure interaction was executed with ANSYS Workbench software. The blood was assumed to be an incompressible Newtonian fluid, and the vessel was assumed to be an isotropic, linear elastic material. Hemodynamic parameters and the effect of an acute take-off angle were statistically analyzed. Results: During the systolic period, the wall pressure in the right coronary artery was significantly reduced in patients with an anomalous origin of the right coronary artery (t = 1.32 s, P=0.0001; t =1.34-1.46 s, P<0.0001). The wall shear stress in the abnormal group was higher at the beginning of the systolic period (t =1.24 s, P=0.0473; t =1.26 s, P=0.0193; t =1.28 s, P=0.0441). The acute take-off angle was smaller in patients with clinical symptoms (27.81 degrees +/- 4.406 degrees) than in patients without clinical symptoms (31.86 degrees +/- 2.789 degrees; P=0.017). In the symptomatic group, pressure was negatively correlated with the acute take-off angle (P=0.0185-0.0341, r=-0.459 to -0.4167). Conclusions: This study shows that an anomalous origin of the right coronary artery from the left coronary artery sinus causes changes in hemodynamic parameters, and that an acute take-off angle in patients with this anomaly is associated with terminal ischemia of the right coronary artery.