Brown, James Thomas;
(2025)
Cardiovascular Magnetic Resonance Augmented Cardiopulmonary Exercise Testing (CMR-CPET) in Exercise Intolerance.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
1.1 Background Exercise intolerance is common to many diseases. Investigation of exercise intolerance frequently isolates the respiratory and/or cardiovascular systems, but this approach neglects other systems that can contribute significantly . Furthermore, many investigations are performed in the resting state. Without assessing all relevant systems in the exercise state, any understanding of exercise intolerance would be incomplete. Combining Cardiovascular Magnetic Resonance Imaging (CMR) and Cardiopulmonary Exercise Testing (CPET) - “CMR-CPET” - allows simultaneous and comprehensive measurement of physiological metrics that determine exercise capacity. CPET allows measurement of oxygen consumption (VO2) and carbon dioxide production (VCO2), and derivation of various metrics associated with respiratory and metabolic function. CMR allows accurate measurement of cardiac output (CO) and ventricular size and function. From these two tests, arteriovenous blood oxygen content gradients (avO2) can be calculated. This metric represents tissue oxygen extraction at the skeletal muscle level. A comprehensive assessment of the respiratory, cardiovascular and musculoskeletal system function is therefore possible with this technique at rest, and importantly, during exercise. 1.2 Aims In this thesis, using CMR-CPET, I aimed to assess the mechanisms affecting exercise tolerance in different patient groups. Firstly, I measured these CMR-CPET metrics at rest and at peak exercise, examining differences between groups. Secondly, I assessed if these metrics provided prognostic information in patients with systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH). 1.3 Results and Conclusions I demonstrated that there are differences in tissue oxygen extraction at peak exercise which may explain exercise capacity differences between subtypes of pulmonary arterial hypertension, and differences in stroke volume augmentation during exercise in patients with prolonged COVID-19 symptoms. Finally, I showed that in SSc-PAH, right ventricular contractile reserve provides additional prognostic information to current risk stratification tools. CMR-CPET aids our understanding of the mechanisms causing exercise intolerance, provides novel biomarkers and identifies potential treatment targets.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Cardiovascular Magnetic Resonance Augmented Cardiopulmonary Exercise Testing (CMR-CPET) in Exercise Intolerance |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2025. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Cardiovascular Science |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10207692 |
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