Biomechanics of Failed Pulmonary Autografts Compared With Normal Pulmonary Roots

Abstract

Failed pulmonary autografts retained nonlinear response to mechanical loading typical of healthy human arterial tissue. Remodeling increased wall thickness but decreased wall stiffness in failed autografts. Increased compliance may explain progressive autograft root dilatation in autograft failures.

Biomechanics of Failed Pulmonary Autografts Compared to Native Aortic Roots

“…Availability of explanted pulmonary autograft specimens offered a unique opportunity to study the biomechanical consequences of remodeling after the Ross operation. In a previous study, altered biomechanical characteristics were shown in explanted autografts compared with native pulmonary roots at pulmonary pressures [12]. In this study, we have demonstrated that autograft roots, explanted after progressive dilatation, did not remodel to represent native aortic roots biomechanically at systemic pressures in this patient population.…”

“…Understanding the biomechanics of vascular remodeling in explanted autografts is important for designing strategies to prevent dilatation. We previously demonstrated that vascular remodeling in explanted autografts resulted in increased compliance compared to native pulmonary roots at pulmonary pressures [12]. We hypothesized that pulmonary autografts explanted after progressive dilatation were also more compliant than native aortic roots at systemic pressures.…”

Numerical simulation of arterial remodeling in pulmonary autografts

“…Our results show that a valveless pulmonary autograft placed in aortic position will remodel such that its macroscopic behavior leans more towards aorta-like behavior, as measured through planar biaxial tensile tests. In contrast, when studying excessively dilated pulmonary autografts in ten patients, Mookhoek et al [11,12] observed a decreased stiffness compared to both the native aorta and pulmonary artery, suggesting a failure of the tissue to remodel. Developing a mathematical model about this phenomenon may help to understand neoaortic valve failures, assuming that pulmonary (neoaortic) root dilatation is a major determinant of neoaortic valve regurgitation.…”

Pulmonary autograft in aortic position: is everything known?

“…The study of Mookhoek et al (50) adds a piece in the puzzle of the mechanical phenomena related to the dilatation of pulmonary autograft under systemic conditions. The authors focused their attention on the idea that failed pulmonary autografts retained nonlinear response to mechanical loading typical of healthy human arterial tissue, as nonlinear stress-strain response was present in both failed autografts and normal pulmonary roots.…”

“…The authors applied the mathematical-physical model in which the explanted autograft and pulmonary roots were assumed incompressible and nonlinear hyper-elastic materials (50). They found that non-linear stress-strain response was present in both failed and normal pulmonary roots, but remodeling increased wall thickness and decreased stiffness in the failed specimens after Ross operation.…”