Moderate intensity supine exercise causes decreased cardiac volumes and increased outer volume variations - a cardiac magnetic resonance imaging study

Abstract

Background The effects on left and right ventricular (LV, RV) volumes during physical exercise remains controversial. Furthermore, no previous study has investigated the effects of exercise on longitudinal contribution to stroke volume (SV) and the outer volume variation of the heart. The aim of this study was to determine if LV, RV and total heart volumes (THV) as well as cardiac pumping mechanisms change during physical exercise compared to rest using cardiac magnetic resonance imaging (CMR). Methods 26 healthy volunteers (6 women) underwent cine CMR at rest and exercise. Exercise was performed using a custom built ergometer for one-legged exercise in the supine position during breath hold imaging. Cardiac volumes and atrio-ventricular plane displacement were determined. Heart rate (HR) was obtained from ECG. Results HR increased during exercise (60 ± 2 to 94 ± 2 bpm, p < 0.001). LVEDV remained unchanged (p = 0.81) and LVESV decreased with -9 ± 18% (p < 0.05) causing LVSV to increase with 8 ± 3% (p < 0.05) (Figure 1A-C). RVEDV and RVESV decreased (-7 ± 10% and -24 ± 14% respectively, p < 0.001) and RVSV was increased with 5 ± 17% although not statistically significant (p = 0.18) (Figure 1 D-F). Longitudinal contribution to RVSV decreased during exercise (-6 ± 15%, p < 0.05) but was unchanged for LVSV (p = 0.74). THV decreased during exercise (-4 ± 1%, p < 0.01) and total heart volume variation (THVV) increased during exercise from 5.9 ± 0.5% to 9.7 ± 0.6%, p < 0.001) (Figure 2). Conclusions