title: Left ventricular unloading decreases rate of isovolumic right ventricular pressure decline.
abstract: To determine whether direct ventricular interaction affects right ventricular (RV) relaxation, we compared the minimum rate of change of RV pressure (dP/dtmin) and the time constant, tau, of isovolumic RV pressure decline in open-chest, anesthetized pigs following a normal left ventricular (LV) contraction and an acutely unloaded LV contraction. Rapid removal of blood via the LV apex into a prosthetic ventricle during a single systole decreased the LV pressure-time integral 68.3% and peak systolic pressure 49.9% without changing RV end-diastolic conditions. Micromanometers measured ventricular chamber pressures during single RV isovolumic beats, which were produced by transient pulmonary artery occlusion in both the control and the LV-unloaded states. When the LV was unloaded, RV tau rose significantly from 41.7 +/- (SD) 7.1 to 49.8 +/- 9.4 ms, P < 0.005 (pericardium intact) and 42.9 +/- 10.8 to 51.8 +/- 13.9 ms, P < 0.005 (pericardium opened). Simultaneously, RV dP/dtmin decreased from -400.5 +/- 136.6 to -288.3 +/- 46.8 mmHg/s, P = 0.14 (pericardium intact), and -342.4 +/- 104.2 to -241.2 +/- 118.9 mmHg/s, P < 0.01 (pericardium opened). These data indicate that LV systolic unloading decreases the rate of RV relaxation. We conclude that RV relaxation is influenced by direct anatomic ventricular interaction.
authors.affiliation: Department of Cardiac Surgery, California Pacific Medical Center, San Francisco 94115.
authors.forename: C D
authors.initials: CD
authors.lastname: Brown
authors.forename: E
authors.initials: E
authors.lastname: Chow
authors.forename: D J
authors.initials: DJ
authors.lastname: Farrar
mesh_terms: D000818:Animals; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000033:anatomy & histology / Q000502:physiology*; D006339:Heart Rate; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D009200:Myocardial Contraction; D010496:Pericardium / Q000502:physiology; D011651:Pulmonary Artery / Q000502:physiology; D013552:Swine; D013599:Systole; D016277:Ventricular Function, Left