Quantification of vascular graft compliance under physiological loading conditions of the ascending aorta

Abstract

[ES] Las enfermedades aórticas letales, como los aneurismas y las disecciones, que involucran anomalías en las paredes de la aorta, son tratadas mediante reparación endovascular con la inserción de una endoprótesis (stent). Este dispositivo de malla ayuda a mantener el vaso sanguíneo abierto, pero su rigidez puede causar complicaciones como fugas de sangre, trombosis, daño local o fallo del injerto. Este estudio tiene como objetivo cuantificar el comportamiento de un injerto vascular sintético bajo diferentes rangos de cargas fisiológicas de la aorta ascendente, con el propósito de determinar la complacencia del vaso a través de diversas mediciones de volumen y presión. Para ello, se realizarán pruebas que incluyen tensión uniaxial, torsión e inflación. El objetivo es mejorar los resultados del tratamiento y reducir los riesgos asociados a este procedimiento.

[EN] Advancements in the treatment of vascular diseases require a deep understanding of the biomechanical properties of vascular grafts. This thesis focuses on evaluating the mechanical behavior of a synthetic Dacron vascular graft, with an emphasis on the ascending aorta, which is the most important artery in the cardiovascular system and is responsible for managing the high pressure blood flow coming directly from the heart. Despite progress in graft technology, achieving accurate compliance with the mechanical behaviour of the aorta remains a challenge. The main objective is to evaluate the compliance and deformation responses of the graft under various physiological conditions: normotension, hypertension, and hypotension. A testing protocol was developed, involving controlled axial forces, inflation pressures, and torsion to simulate different blood pressure conditions. The compliance of the graft was measured through extension-inflation-torsion tests and some calculations. The results revealed that the graft compliance varied with pressure conditions, displaying nonlinear stress-strain behavior typical of biological tissue properties. Specifically, under hypertensive conditions, the graft exhibited increased stiffness and reduced compliance, mirroring the natural response of blood vessels to high pressure. These conclusions emphasize the importance of further research to optimize graft performance, particularly under hypertensive conditions, and to explore customized solutions for different aortic segments.