Dynamic right and left ventricular interactions in the rabbit: simultaneous measurement of ventricular pressure-volume loops.
OBJECTIVE
This study was performed to characterize the dynamic factors determining ventricular interdependence in an open-pericardium intact animal model.


METHODS
Simultaneous measures of right ventricular (RV) and left ventricular (LV) pressures and volumes in 6 urethane-anesthetized open-chested, open-pericardium rabbits. RV and LV V were calculated every 2 milliseconds. Measurements were made at initial baseline blood volume, and again after two infusions of 20 mL/kg isoconductive colloid solution. At each blood volume level, partial aortic (AO), pulmonary artery (PAO), and inferior vena caval (IVC) occlusions were performed. Biventricular diastolic compliance and end-systolic elastance were calculated from these data.


RESULTS
Baseline end-diastolic (ED) and end-systolic (ES) V were 3.29 +/- 0.55 and 2.43 +/- 0.33 mL (mean +/- SD) for the LV, and 3.38 +/- 1.56 and 2.84 +/- 1.36 mL for the RV, respectively. AO increased all LV pressure and volume (P < .05) but did not alter RV ED volume (2.85 +/- 1.20 mL) or ED pressure (3.3 +/- 2.0 to 3.6 +/- 2.1 mm Hg). PAO increased RV ES pressure (P < .05) but did not alter RV ED volume, ED pressure, or ES volume, although it decreased LV ED volume (2.82 +/- 0.59, P < .05). AO also immediately increased end-systolic RV elastance to a value greater than that defined by IVC (7.9 +/- 4.4 to 10.9 +/- 6.6 mm Hg/mL, P < .05). Intravascular volume expansion though increasing baseline pressure and volume, did not alter qualitatively biventricular responses to AO, PA, or IVC.


CONCLUSIONS
Ventricular interdependence has both systolic and diastolic components that have differing directional effects. In the pericardectomized rabbit, increases in RV ED volume decrease LV ED volume by decreasing LV diastolic compliance, but do not alter LV systolic function. Whereas, increases in LV ED volume decrease RV ES volume resulting in an increase in RV maximal elastance, but minimally alter RV diastolic function.
Pinsky
M R
MR
Department of Anesthesiology and Critical Care Medicine, University of Pittsburgh, USA.
Perlini
S
S
Solda
P L
PL
Pantaleo
P
P
Calciati
A
A
Bernardi
L
L
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D001810:Blood Volume / Q000502:physiology*; D006328:Cardiac Catheterization / Q000295:instrumentation; D002306:Cardiac Volume / Q000502:physiology; D002307:Cardiography, Impedance / Q000295:instrumentation; D003971:Diastole / Q000502:physiology; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000502:physiology; D011817:Rabbits; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation; D013318:Stroke Volume / Q000502:physiology*; D013599:Systole / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*; D016278:Ventricular Function, Right / Q000502:physiology*