Ikeda M; Kyushu University, Fukuoka, Japan.
Hieda M; Yoshida K; Imabayashi M;

Physiological Reports. 14(21), 2026 Nov.

Exercise cardiovascular magnetic resonance imaging (exCMR) enables
quantitative assessment of biventricular responses during physiological
stress. We aimed to characterize right ventricular (RV)-left ventricular
(LV) volumetric relationships in healthy adults using exCMR. Eighteen
healthy adults (9 males, 9 females) underwent exCMR.
Electrocardiography-gated short-axis cine and phase-contrast flow images
were obtained at rest, at a target heart rate of 100 beats/min (Ex1), and
at 40% of peak work rate determined by cardiopulmonary exercise testing
(Ex2). The RV-LV volumetric relationship was operationally represented by
the RV/LV end-diastolic and end-systolic volume ratios derived from
simultaneous cine volumetry. All participants completed the protocol, and
all cine and phase-contrast datasets were analyzed. During exercise,
stroke volume increased in both ventricles predominantly through a
reduction in end-systolic volume (ESV), whereas end-diastolic volume (EDV)
changed little. Cine-derived LV and RV stroke volumes showed internal
concordance with phase-contrast flow-derived measurements. The RV/LV EDV
ratio (1.03, 1.03, and 1.03 at rest, Ex1, and Ex2, respectively) and RV/LV
ESV ratio (1.09, 1.09, and 1.08 at rest, Ex1, and Ex2, respectively)
remained stable across stages. Healthy adults maintained a stable relative
RV-LV volumetric relationship during low-to-moderate intensity supine
exercise. These findings provide quantitative physiological reference data
for future disease-focused studies.