Investigation of fluid dynamic effects of endovascular intervention in a model of descending aortic dissection

Abstract

With advances in endovascular technology and technique, Thoracic EndoVascular Aortic Repair (TEVAR) has emerged as an integral component of the management of Stanford Type B dissection of the descending aorta. Whereas this modality is considered vital in the treatment of patients experiencing severe complications as a result of dissection, it has not been shown to be demonstratively superior to treatment with medical therapy alone in the absence of malperfusion, rupture, or aneurysmal degeneration. However, results from various clinical studies on the relative benefits of these therapies may be confounded by the vast heterogeneity in dissection anatomy and hemodynamics. Therefore, little is known regarding which patients should undergo TEVAR, as well as the effect of stent-graft deployment on the functional status of the aorta. In order to address this knowledge gap, compliant models of the aorta possessing a mobile intimal flap mimicking dissection were fabricated and imaged via four-dimensional phase contrast magnetic resonance (4D PCMR) imaging sensitive to fluid flow. We aimed to understand how the fluid flow varies with changes to the dissection anatomy as well as the effect of varying anatomies on the fluid shear rate, which has been related to the thrombotic potential of blood-contacting surfaces. Furthermore, we aimed to study the effects of graft deployment on these hemodynamic effects. Dissection induced flow reversal in the aorta, with concomitant low and oscillatory shear zones, which were reduced in dissections with multiple tears. Device deployment was found to restore normal hemodynamics locally, while preserving distal hemodynamic alterations. These findings suggest a potential for risk-stratification based on anatomical and functional imaging as well as more aggressive intervention to rectify aberrant fluid mechanics of the dissected aorta.