Biomechanical remodeling of the murine descending thoracic aorta during late-gestation pregnancy

Ana I Vargas; Samar A Tarraf; Timothy P Fitzgibbons; Chiara Bellini; Rouzbeh Amini

doi:10.1016/j.crphys.2023.100102

Biomechanical remodeling of the murine descending thoracic aorta during late-gestation pregnancy

Curr Res Physiol. 2023 Jul 18:6:100102. doi: 10.1016/j.crphys.2023.100102. eCollection 2023.

Authors

Ana I Vargas¹, Samar A Tarraf¹, Timothy P Fitzgibbons², Chiara Bellini¹, Rouzbeh Amini^{1

3}

Affiliations

¹ Department of Bioengineering, Northeastern University, Boston, MA, 02115, United States.
² Department of Medicine, Division of Cardiovascular Medicine, University of Massachusetts Medical School, Worcester, MA, 01655, United States.
³ Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, United States.

Abstract

With the rise in maternal mortality rates and the growing body of epidemiological evidence linking pregnancy history to maternal cardiovascular health, it is essential to comprehend the vascular remodeling that occurs during gestation. The maternal body undergoes significant hemodynamic alterations which are believed to induce structural remodeling of the cardiovascular system. Yet, the effects of pregnancy on vascular structure and function have not been fully elucidated. Such a knowledge gap has limited our understanding of the etiology of pregnancy-induced cardiovascular disease. Towards bridging this gap, we measured the biaxial mechanical response of the murine descending thoracic aorta during a normotensive late-gestation pregnancy. Non-invasive hemodynamic measurements confirmed a 50% increase in cardiac output in the pregnant group, with no changes in peripheral blood pressure. Pregnancy was associated with significant wall thickening ( ∼14%), an increase in luminal diameter ( ∼6%), and material softening in both circumferential and axial directions. This expansive remodeling of the tissue resulted in a reduction in tensile wall stress and intrinsic tissue stiffness. Collectively, our data indicate that an increase in the geometry of the vessel may occur to accommodate for the increase in cardiac output and blood flow that occurs in pregnancy. Similarly, wall thickening accompanied by increased luminal diameter, without a change in blood pressure may be a necessary mechanism to decrease the tensile wall stress, and avoid pathophysiological events following late gestation.

Keywords: Aortic distensibility; Aortic stiffness; Late gestation; Law of Laplace; Normotensive pregnancy; Tensile wall stress.