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Why is exercise capacity reduced in subjects with pectus excavatum?
L Zhao1, M S Feinberg, M Gaides
1Pulmonary and Heart Institutes, Sheba Medical Center, Tel-Hashomer, Israel; and Sackler Medical School, Tel-Aviv University, Tel-Aviv, Israel.
The Journal of Pediatrics
|February 5, 2000
Summary
Patients with pectus excavatum (PE) experience reduced exercise capacity when sitting due to impaired heart function. Exercise performance improves when lying down, suggesting venous return limitations affect upright exercise in PE.
Area of Science:
- Cardiology
- Exercise Physiology
- Thoracic Surgery
Background:
- Exercise capacity is frequently limited in individuals with pectus excavatum (PE).
- The underlying physiological mechanisms for this exercise intolerance in PE remain largely unknown.
- Understanding these mechanisms is crucial for improving patient management and quality of life.
Purpose of the Study:
- To quantitatively assess exercise capacity in patients with PE.
- To investigate the role of impaired venous return to the heart in exercise intolerance among PE patients.
- To compare exercise parameters between PE patients and healthy controls.
Main Methods:
- 13 patients with PE and 20 healthy controls underwent incremental cycling tests in both sitting and supine positions.
- Exercise stroke volume (SV) was measured using Doppler echocardiography during the tests.
- Peak oxygen uptake (V'O(2)max) was determined as a measure of exercise capacity.
Main Results:
- Peak oxygen uptake (V'O(2)max) was significantly lower in PE patients compared to controls when exercising in the sitting position (P =.02).
- No significant difference in V'O(2)max was observed between groups during supine exercise.
- Stroke volume (SV) was higher during supine exercise than sitting exercise in PE patients, but not in controls, indicating a positional effect on cardiac filling.
Conclusions:
- Patients with PE exhibit reduced exercise capacity and stroke volume in the sitting position.
- Exercise performance in PE patients improves significantly when transitioning to a supine position.
- These findings suggest that reduced cardiac filling due to impaired venous return in the upright position contributes to exercise intolerance in pectus excavatum.