The hemodynamic study on the effects of entry tear and coverage in aortic dissection

Abstract

In this work, the hemodynamic effects of the type-A aortic dissection in different entry and covering entry tear positions were mainly studied. It provides a new method or idea in the field of the aortic dissection hemodynamics, and it is of profound significance to provide basic theoretical research on the development of aortic dissection in the aspect of clinical judgment. Two type-A aortic dissection models with different entry tear positions (Model 1: The entry tear was located at the entrance of the ascending aorta, Model 2: The entry tear was located at the starting position of the descending aorta) were reconstructed according to the computed tomography (CT) images of the patients. In our study, the thoracic aortic endovascular repair was simulated by covering the entry tear (Model 3). To clarify the hemodynamic effects of entry tear and coverage, the comparative study on the true lumen (TL) and false lumen (FL) blood flow patterns of three models were carried out numerically. The velocity vector, flow ratio, pressure, time-averaged wall shear stress (TAWSS) and relative residence time (RRT) were calculated to evaluate the hemodynamic changes. The results of this work indicated that (I) the velocity of entry tear at the aorta entrance was higher; (II) The helical development of the TL and FL might be related to the helical nature of aortic arch; (III) The blood flow which passing the FL of Model 1, Model 2 and Model 3 in one cardiac cycle were approximately 26.63%, 13.39% and 1%, respectively; (IV) The difference in intima wall pressure of the TL and FL were showed a strong pulsation; (V) The TAWSS distribution in TL and FL were completely different (the TAWSS in TL intima >8 Pa, the TAWSS in FL intima <4 Pa). In brief, the aortic morphology and location of the entry tear were found to have a significant effect on the hemodynamics of the aortic dissection. In addition, the CFD method is used to obtain multi-dimensional hemodynamic information such as velocity field, pressure, TAWSS and RRT, which can help clinicians better understand the development of type-A aortic dissection and provide a theoretical basis for clinical treatment.