University of Oulu

Kiema M, Sarin JK, Kauhanen SP, Torniainen J, Matikka H, Luoto E-S, Jaakkola P, Saari P, Liimatainen T, Vanninen R, Ylä-Herttuala S, Hedman M and Laakkonen JP (2022) Wall Shear Stress Predicts Media Degeneration and Biomechanical Changes in Thoracic Aorta. Front. Physiol. 13:934941. doi: 10.3389/fphys.2022.934941

Wall shear stress predicts media degeneration and biomechanical changes in thoracic aorta

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Author: Kiema, Miika1; Sarin, Jaakko K.2,3,4; Kauhanen, S. Petteri2;
Organizations: 1A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
2Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland
3Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
4Department of Medical Physics, Medical Imaging Center, Pirkanmaa Hospital District, Tampere, Finland
5Department of Heart and Thoracic Surgery, Kuopio University Hospital, Heart Center, Kuopio, Finland
6Research Unit of Medical Imaging, Physics and Technology, Oulu University Hospital, Oulu, Finland
7Science Service Center, Kuopio University Hospital, Kuopio, Finland
8Gene Therapy Unit, Kuopio University Hospital, Kuopio, Finland
9Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 4 MB)
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Language: English
Published: Frontiers Media, 2022
Publish Date: 2023-06-30


Objectives: In thoracic aortic aneurysm (TAA) of the ascending aorta (AA), AA is progressively dilating due to the weakening of the aortic wall. Predicting and preventing aortic dissections and ruptures in TAA continues to be challenging, and more accurate assessment of the AA dilatation, identification of high-risk patients, and timing of repair surgery are required. We investigated whether wall shear stress (WSS) predicts pathological and biomechanical changes in the aortic wall in TAA.

Methods: The study included 12 patients with bicuspid (BAV) and 20 patients with the tricuspid aortic valve (TAV). 4D flow magnetic resonance imaging (MRI) was performed a day before aortic replacement surgery. Biomechanical and histological parameters, including assessing of wall strength, media degeneration, elastin, and cell content were analyzed from the resected AA samples.

Results: WSSs were greater in the outer curves of the AA compared to the inner curves in all TAA patients. WSSs correlated with media degeneration of the aortic wall (ρ = -0.48, ρ < 0.01), elastin content (ρ = 0.47, ρ < 0.01), and aortic wall strength (ρ = -0.49, ρ = 0.029). Subsequently, the media of the outer curves was thinner, more rigid, and tolerated lower failure strains. Failure values were shown to correlate with smooth muscle cell (SMC) density (ρ = -0.45, ρ < 0.02), and indicated the more MYH10⁺ SMCs the lower the strength of the aortic wall structure. More macrophages were detected in patients with severe media degeneration and the areas with lower WSSs.

Conclusion: The findings indicate that MRI-derived WSS predicts pathological and biomechanical changes in the aortic wall in patients with TAA and could be used for identification of high-risk patients.

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Series: Frontiers in physiology
ISSN: 1664-042X
ISSN-E: 1664-042X
ISSN-L: 1664-042X
Volume: 13
Article number: 934941
DOI: 10.3389/fphys.2022.934941
Type of Publication: A1 Journal article – refereed
Field of Science: 217 Medical engineering
Funding: This study was supported by the Academy of Finland (JPL 321535 and 328835), Finnish Foundation of Cardiovascular Diseases (JPL) and Oiva Vaittinen will donation (18405).
Copyright information: © 2022 Kiema, Sarin, Kauhanen, Torniainen, Matikka, Luoto, Jaakkola, Saari, Liimatainen, Vanninen, Ylä-Herttuala, Hedman and Laakkonen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.