Acute Effects of Submaximal Aerobic Exercise on Aortic Wall Stress Measured by Magnetic Resonance Imaging in Patients with Thoracic Aortic Disease
Bibliographic record
Abstract
Background: Current guidelines recommend that clinically stable patients with thoracic aortic disease (AD, including aneurysm or dissection) with well-controlled blood pressure (BP) perform regular ‘mild-to-moderate’ intensity aerobic exercise. However, these guidelines are not based on physiological evidence, and may be restrictive to some fitter patients. Importantly, no studyhas measured thoracic aortic wall stress (AWS; a measure of stress on the aorta and an independent predictor of dissection and/or rupture) during exercise in individuals with or without AD. Purpose: We sought to measure thoracic AWS, using magnetic resonance imaging (MRI), during submaximal aerobic exercise in participants with AD compared to age-matched (i.e., older) and younger healthy controls (OC and YC, respectively). We hypothesized that resting AWS will be higher in AD versus OC and YC but that the response to exercise will not be different between groups, and at moderate exercise will be below the maximal tensile strength reported for human thoracic aorta aneurysm (1200 kPa). Methods: Seven participants with stable AD (2 females, 69±11yrs, 3 with unrepaired ascending aortic aneurysm) were compared to 9 OC (4 females, 66±6yrs) and 7 YC (4 females, 29±6yrs) without AD. Participants underwent comprehensive evaluation of cardiac and aortic structure and function at rest and during light and moderate intensity stepping exercise (Ergospect Cardio Step) using MRI. Cardiac output (Qc) and aortic dimensions were measured at rest and during exercise using ungated free breathing cardiac MRI. Aortic wall thickness was measured at rest using black-blood fat-suppressed cardiac-gated fast spin echo MRI. Circumferential ascending and descending thoracic AWS was calculated in accordance with LaPlace law, as the product of systolic blood pressure and aortic diameter divided by wall thickness. Given that Qc directly influences AWS, we also related the change in AWS to the change in Qc during exercise. Baseline characteristics and AWS/Qc slopes were compared using one-way ANOVA, and a two-way mixed effects ANOVA evaluated the exercise response within and between groups. Results: Ascending AWS was not different between groups at rest (p=0.13), increased with exercise (p<0.01), and the response to exercise did not differ between groups (interaction, p=0.27). Descending AWS was lower in YC at rest (p=0.03), which persisted during all exercise stages (effect of group, p<0.01). The rise in descending AWS was up 3-fold larger in AD (YC: +21±15 kPa; OC: +46±18 kPa; AD: +62±30 kPa) resulting in a significant interaction (p<0.01). Importantly, all AWS values during exercise were below the aneurysmal rupture threshold. For example, at moderate intensity exercise, ascending AWS was 184±42kPa, 235±36kPa, and 216±68kPa in the YC, OC, and AD, respectively, and the highest value reported in any individual was 312kPa. Lastly, patients with AD had higher AWS/Qc slopes in both the ascending (YC: 6±5kPa/L/min; OC, 9±4 kPa/L/min; AD: 18±7kPa/L/min; p=0.01) and descending thoracic aorta (YC: 4±2kPa/L/min; OC: 10±6kPa/L/min; AD: 18±11kPa/L/min; p<0.01). Conclusion: In clinically stable, normotensive patients with thoracic AD, ascending and descending AWS remains well below the aneurysm rupture threshold during moderate-intensity aerobic exercise. Compared to YC, the AWS response to exercise is higher in OC, and even more so in patients with thoracic AD, which is further demonstrated when indexed to Qc. These preliminary findings highlight the potential of AWS as a novel quantitativemetric for safely prescribing individualized exercisetraining programs for these patients. Dr. Margaret "Marmie" Perkins Hess Heart Research Pilot Grant (Cardiovascular Research Institute, UofA). PDF in Health Innovation & Enhancement (Alberta Innovates). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".