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Front. Physiol. | doi: 10.3389/fphys.2019.00269

Exercise-induced changes in MRI-derived metrics of pulmonary artery stiffness in pulmonary hypertension

 Omid Forouzan1, Eric Dinges1, James R. Runo2, Jonathan G. Keevil2, Jens C. Eickhoff2, Christopher Francois2 and  Naomi C. Chesler1*
  • 1College of Engineering, University of Wisconsin-Madison, United States
  • 2University of Wisconsin School of Medicine and Public Health, United States

Background– Pulmonary hypertension causes pulmonary artery (PA) stiffening, which overloads the right ventricle (RV). Since symptoms of pulmonary hypertension (PH) are exacerbated by exercise, exercise-induced PA stiffening is relevant to cardiopulmonary status. Here we sought to demonstrate the feasibility of using magnetic resonance imaging (MRI) for non-invasive assessment of exercise-induced changes in PA stiffness in patients with PH.

Methods–MRI was performed on 7 PH patients and 8 age-matched control subjects at rest and during exercise stress. Main pulmonary artery (MPA) relative area change (RAC) and pulse wave velocity (PWV) were measured from 2D-PC images. Invasive right heart catheterization (RHC) was performed on 5 of the PH patients in conjunction with exercise stress to measure MPA pressures and stiffness index (β).

Results– Heart rate and cardiac index were significantly increased with exercise in both groups. In controls, RAC decreased from 0.27±0.05 at rest to 0.22±0.06 with exercise (P<0.05); a modest increase in PWV was not significant (P=0.06). In PH patients, RAC decreased from 0.15±0.02 to 0.11±0.01 (P<0.05) and PWV and β increased from 3.9±0.54 m/s and 1.86±0.12 at rest to 5.75±0.70 m/s and 3.25±0.26 with exercise (P<0.05 for both), respectively. These results confirm increased MPA stiffness with exercise stress in both groups and the non-invasive metrics of MPA stiffness correlated well with β. Finally, as assessed by PWV but not RAC, PA stiffness of PH patients increased more than that of controls for comparable levels of moderate exercise.

Conclusion- These results demonstrate the feasibility of using MRI for non-invasive assessment of exercise-induced changes in MPA stiffness in a small, heterogeneous group of PH patients in a research context. Similar measurements in a larger cohort are required to investigate differences between PWV and RAC for estimation of MPA stiffness.

Keywords: Relative area change, pulse wave velocity (PWV), Magnetic Resonace Imaging (MRI), Exercise, Stiffness &amp; its variations

Received: 19 Jul 2018; Accepted: 28 Feb 2019.

Edited by:

Fernando Teran Arce, University of Arizona, United States

Reviewed by:

Gabor Kovacs, Ludwig Boltzmann Institute for Lung Vascular Research, Austria
Farbod N. Rahaghi, Brigham and Women's Hospital, Harvard Medical School, United States  

Copyright: © 2019 Forouzan, Dinges, Runo, Keevil, Eickhoff, Francois and Chesler. 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.

* Correspondence: Prof. Naomi C. Chesler, College of Engineering, University of Wisconsin-Madison, Madison, United States, chesler@engr.wisc.edu