Magnetic resonance imaging-based hemodynamic wall shear stress alters aortic wall tissue biomechanics in bicuspid aortic valve patients

Miriam Nightingale, Michael Baran Scott, Taisiya Sigaeva, David Guzzardi, Julio Garcia, S. Chris Malaisrie, Patrick McCarthy, Michael Markl, Paul W.M. Fedak, Elena S. Di Martino, Alex J. Barker*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Objective: In this study we aimed to conclusively determine whether altered aortic biomechanics are associated with wall shear stress (WSS) independent of region of tissue collection. Elevated WSS in the ascending aorta of patients with bicuspid aortic valve has been shown to contribute to local maladaptive aortic remodeling and might alter biomechanics. Methods: Preoperative 4-dimensional flow magnetic resonance imaging was performed on 22 patients who underwent prophylactic aortic root and/or ascending aorta replacement. Localized elevated WSS was identified in patients using age-matched healthy atlases (n = 60 controls). Tissue samples (n = 78) were collected and categorized according to WSS (elevated vs normal) and region. Samples were subjected to planar biaxial testing. To fully quantify the nonlinear biomechanical response, the tangential modulus (local stiffness) at a low-stretch (LTM) and high-stretch (HTM) linear region and the onset (TZo) and end stress of the nonlinear transition zone were measured. A linear mixed effect models was implemented to determine statistical relationships. Results: A higher LTM in the circumferential and axial direction was associated with elevated WSS (P = .007 and P = .018 respectively) independent of collection region. Circumferential TZo and HTM were higher with elevated WSS (P = .024 and P = .003); whereas the collection region was associated with variations in axial TZo (P = .013), circumferential HTM (P = .015), and axial HTM (P = .001). Conclusions: This study shows strong evidence that biomechanical changes in the aorta are strongly associated with hemodynamics, and not region of tissue collection for bicuspid valve aortopathy patients. Elevated WSS is associated with tissue behavior at low stretch ranges (ie, LTM and TZo).

Original languageEnglish (US)
Pages (from-to)465-476.e5
JournalJournal of Thoracic and Cardiovascular Surgery
Volume168
Issue number2
DOIs
StatePublished - Aug 2024

Funding

Funding for this work provided by The National Heart, Lung, and Blood Institute of the National Institutes of Health under award numbers R01HL133504 and R01HL115828 . The Melman Bicuspid Aortic Valve Program . Bluhm Cardiovascular Institute , and The National Science and Engineering Research Council of Canada Discovery grant RGPIN-2019 to 07178 .

Keywords

  • 4D flow MRI
  • aortic aneurysm
  • bicuspid aortic valve
  • tissue biomechanics
  • wall shear stress

ASJC Scopus subject areas

  • Surgery
  • Pulmonary and Respiratory Medicine
  • Cardiology and Cardiovascular Medicine

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