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

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 less than 0.01). RVEF increased from 44% +/- 4 (mean +/- SD) to 60% +/- 6 (P less than 0.001). LVEF increased from 62% +/- 6 to 76 +/- 5 (P less than 0.001). A wider scatter was observed in delta RVEF than in delta LVEF. There was a 14% increase in LVEDV-index and a 14% decrease in LVESV-index (P less than 0.001). A multiple regression analysis with delta RVEF as the dependent variable and delta HR, delta systolic BP, delta LVEF, delta LVEDV-index and LVESV-index as independent variables showed a significant correlation between delta RVEF and delta LVEF and delta systolic BP (P less than 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.