Impact of coronary tortuosity on the coronary blood flow: a 3D computational study.

Tortuous coronary arteries are commonly observed but the etiology and clinical importance are still unclear. Hemodynamic factors are vital modulators of the vascular structure and a full understanding of hemodynamic changes caused by the coronary tortuosity (CT) is meaningful for clinical researches. A three-dimensional computational fluid dynamic study was conducted to evaluate hemodynamic changes caused by the CT. Six idealized small sections of the left anterior descending coronary artery (LAD) with different levels of tortuosity were employed. The dynamic vessel motion was added to the three-dimensional tortuous coronary models to make the computational results more realistic. The rest and exercise conditions were modeled by specifying proper boundary conditions. Results showed that a low and oscillated wall shear stress (WSS) region was formed at the inner wall downstream of the bend section when the bend angle was larger than 120°. The resistance of the coronary arteries increased up to 92% due to the CT during exercise. A maximum increase of 96% was observed in the mean diastole driving pressure for the CT model as compared to the non-tortuous model during exercise. This study indicated that the severe CT may be a risk factor for atherosclerosis and may make the regulation of the blood flow ineffective during exercise.