Effect of Altered Resistive Load on Left Ventricular Systolic Mechanics in Dogs
Open Access
- 1 March 1982
- journal article
- research article
- Published by Wolters Kluwer Health in Anesthesiology
- Vol. 56 (3) , 195-202
- https://doi.org/10.1097/00000542-198203000-00008
Abstract
The possibility that end-systolic volume is reduced at a given aortic and left ventricular (LV) pressure when systemic vascular resistance is reduced was studied. In 7 anesthetized dogs pretreated with propranolol to block reflex changes in contractility, aortic pressure and ventricular volumes were measured under baseline conditions and after reducing resistive load by opening 2 peripheral arterio-venous shunts. When resistive load was reduced, blood pressure was maintained with plasma volume expansion. Real size biplane ventricular end-diastolic areas were obtained using scintigraphic techniques and end-diastolic volumes were calculated using the area-length equation. Thermodilution stroke volume was subtracted from end-diastolic volume to obtain end-systolic volume. When resistive load decreased, mean ejection rate doubled (P < 0.01) and LV end-systolic volume decreased (P < 0.005), despite constant aortic pressure. In 7 additional dogs, pretreated with propranolol, LV pressure, instantaneous and peak LV flow were measured before and after resistive load was reduced by opening 1 shunt. Despite constant LV pressures, instantaneous, peak and total flow increased when resistance was reduced. Evidently, the LV shortens farther and faster during ejection against the same aortic and LV pressure when resistive afterload is reduced.This publication has 14 references indexed in Scilit:
- The ventricular pressure-volume diagram revisited.Circulation Research, 1978
- Contractile state of the left ventricle in man as evaluated from end-systolic pressure-volume relations.Circulation, 1977
- Vasodilator treatment for acute and chronic heart failure.Heart, 1977
- Effects of sodium nitroprusside on left ventricular diastolic pressure-volume relations.Journal of Clinical Investigation, 1977
- Left ventricular force-length relations of isovolumic and ejecting contractionsAmerican Journal of Physiology-Legacy Content, 1976
- Physiological loading of isolated mammalian cardiac muscle.Circulation Research, 1976
- Arterial impedance as ventricular afterload.Circulation Research, 1975
- SELECTIVE BLOCKADE OF ADRENOCEPTIVE BETA RECEPTORS IN THE HEARTBritish Journal of Pharmacology, 1968
- Outflow Resistance as an Independent Determinant of Cardiac PerformanceCirculation Research, 1961
- Compensations of cardiac output and other circulatory functions in areflex dogs with large A-V fistulasAmerican Journal of Physiology-Legacy Content, 1961