Computational model of coronary tortuosity

Coronary tortuosity is the abnormal curving and twisting of the coronary arteries. Although the phenomenon of coronary tortuosity is frequently encountered by cardiologists its clinical significance is unclear. It is known that coronary tortuosity has significant influence on the hemodynamics inside the coronary arteries, but it is difficult to draw definite conclusions due to the lack of patient-specific studies and an absence of a clear definition of tortuosity.

In this work, in order to investigate a relation of coronary tortuosity to such diseases as atherosclerosis, ischemia, and angina, a numerical investigation of coronary tortuosity was performed. First, we studied a correlation between a degree of tortuosity and flow parameters in three simplified vessels with curvature and zero torsion. Next, a statistical analysis based on flow calculations of 23 patient-based real tortuous arteries was performed in order to investigate a correlation between tortuosity and flow parameters, such as pressure drop, wall shear stress distribution, and a strength of helical flow, represented by a helicity intensity, and concomitant risks.

Results of both idealized and patient-specific studies indicate that a risk of perfusion defects grows with an increased degree of tortuosity due to an increased pressure drop downstream an artery. According to the results of the patient-specific study, a risk of atherosclerosis decreases in more tortuous arteries - a result different from an outcome of the idealized study of arteries with zero torsion. Consequently, a modeling of coronary tortuosity should take into account all aspects of tortuosity including a heart shape that introduces additional torsion to arteries. Moreover, strength of a helical flow was shown to depend strongly on a degree of tortuosity and affect flow alterations and accompanying risks of developing atherosclerosis and perfusion defects. A corresponding quantity, helicity intensity, might have a potential to be implemented in future studies as a universal single parameter to describe tortuosity and assess congruent impact on the health of a patient.