Right and left ventricular ejection fraction and left ventricular volume changes at rest and during exercise in normal subjects

The effect of exercise upon right and left ventricular ejection fractions (RVEF and LVEF) as well as the changes upon left ventricular end-diastolic and end-systolic volume indices (LVEDVI and LVESVI) were investigated. Twenty-two normal subjects were studied at rest and during upright submaximal exercise. RVEF was determined using a first-pass method. LVEF was measured using multiple gated blood pool imaging.During the exercise test ECGs remained normal. HR and BP increased significantly (P<0.01). RVEF increased from 44%±4 (mean±SD) to 60%±6 (P<0.001). LVEF increased from 62%±6 to 76±5 (P<0.001). A wider scatter was observed in ΔRVEF than in ΔLVEF. There was a 14% increase in LVEDV-index and a 14% decrease in LVESV-index (P<0.001). A multiple regression analysis with ΔRVEF as the dependent variable and ΔHR, Δsystolic BP, ΔLVEF, ΔLVEDV-index and LVESV-index as independent variables showed a significant correlation between ΔRVEF and ΔLVEF and δsystolic BP (P<0.05). Our data provide insight into the mechanisms by which the pump performance is increased in normal subjects. The central mechanisms observed are the Starling effect and an increase in contractility of the myocardium. This is connected in the general circulation to an increase in afterload, indicating a redistribution of blood from the vascular beds to the muscles and to the heart.