Bare Metal Stenting for Residual Arch Dissections: A Computational Analysis.

PURPOSE: Type A Thoracic Aortic Dissections are a highly morbid and complex clinical challenge often managed with hemiarch or total arch repair. Hemiarch repair is more commonly performed due to improved neurologic morbidity profile however it leaves behind a residual dissection flap which can lead to aneurysmal degeneration. Bare metal stent placement in conjunction with hemiarch repair is a novel technique which can theoretically avoid leaving a residual dissection flap. In this paper we analyze the biomechanical changes observed after in silico deployment of a bare metal stent in a post-hemiarch type A aortic dissection.

METHODS: We obtain computed tomography scans from pre-operative bare metal stent patients and perform high-fidelity segmentations. This geometry is then utilized for in silico stent deployment via finite element analysis. Deformed geometries are then utilized for computational fluid dynamic simulations to analyze the evolution of pressure gradients in the aorta.

RESULTS: We analyze the resulting geometry from in silico stent deployment for three different stiffness ratios between the flap and aortic wall. We demonstrate an acceptable stress evolution in the stent across all 3 stiffness configurations. We show a reduction in the false luminal volume across all stiffness ratios. Our analysis of pressure distributions that evolve in the aorta show that even in scenarios of high flap stiffness, where the false lumen volume shrinks correspondingly less, we still achieve a reduction in the pressure gradient across the aorta.

CONCLUSION: We show that bare metal stent deployment hemodynamically stabilizes the aorta via our finite element analysis and subsequent computational fluid dynamic modelling.