There is evolving evidence that intense exercise may place a disproportionate load on the right ventricle (RV) when compared with the left ventricle (LV) of the heart. Using a novel method of estimating end-systolic wall stress (ES-σ), we compared the RV and LV during exercise and assessed whether this influenced chronic ventricular remodeling in athletes.
For this study, 39 endurance athletes (EA) and 14 nonathletes (NA) underwent resting cardiac magnetic resonance (CMR), maximal oxygen uptake (V˙O2), and exercise echocardiography studies. LV and RV end-systolic wall stress (ES-σ) were calculated using the Laplace relation (ES-σ = Pr/(2h)). Ventricular size and wall thickness were determined by CMR; invasive and Doppler echo estimates were used to measure systemic and pulmonary ventricular pressures, respectively; and stroke volume was quantified by Doppler echocardiography and used to calculate changes in ventricular geometry during exercise.
In EA, compared with NA, resting CMR measures showed greater RV than LV remodeling. The ratios RV ESV/LV ESV (1.40 ± 0.23 vs 1.26 ± 0.12, P = 0.007) and RV mass/LV mass (0.29 ± 0.04 vs 0.25 ± 0.03, P = 0.012) were greater in EA than in NA. RVES-σ was lower at rest than LVES-σ (143 ± 44 vs 252 ± 49 kdyn·cm−2, P < 0.001) but increased more with strenuous exercise (125% vs 14%, P < 0.001), resulting in similar peak exercise ES-σ (321 ± 106 vs 286 ± 77 kdyn·cm−2, P = 0.058). Peak exercise RVES-σ was greater in EA than in NA (340 ± 107 vs 266 ± 82 kdyn·cm−2, P = 0.028), whereas RVES-σ at matched absolute workloads did not differ (P = 0.79).
Exercise induces a relative increase in RVES-σ which exceeds LVES-σ. In athletes, greater RV enlargement and greater wall thickening may be a product of this disproportionate load excess.
1Department of Medicine, St. Vincent's Hospital, University of Melbourne, Melbourne, AUSTRALIA; 2Cardiology Department, University Hospital, University of Leuven, Leuven, BELGIUM; 3Cardiology Department, St. Vincent's Hospital Melbourne, Melbourne, AUSTRALIA; and 4Alfred Hospital and Baker IDI Heart and Diabetes Institute, Melbourne, AUSTRALIA
Address for correspondence: André La Gerche, M.B.B.S., Ph.D., Department of Cardiology, St. Vincent's Hospital, PO Box 2900, Fitzroy 3065, Australia; E-mail: Andre.LaGerche@svhm.org.au.
Submitted for publication October 2010.
Accepted for publication November 2010.
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