The right and left ventricular intracavitary and transmural pressure-strain relationships.
The magnitude of pericardial pressure and therefore the shape of the right ventricular end-diastolic transmural pressure-volume relationship remains controversial. To investigate ventricular compliance, eight dogs anesthetized with fentanyl were instrumented as follows. Right and left ventricular intracavitary pressures were measured with micromanometer-tipped catheters. Right and left ventricular free wall segment lengths were measured by sonomicrometry. Pericardial pressure was measured over the right and left ventricles by means of flat liquid-containing balloon transducers, and transmural pressures were calculated as the difference between intracavitary and pericardial pressures. After defining the pressure-segment length relationship by vena caval constriction followed by release and blood transfusion, the pericardium and chest were opened widely and the cardiac volume manipulation was repeated; this allowed direct measurement of transmural right ventricular end-diastolic pressure for each level of strain recorded with the chest and pericardium closed. When intracavitary right or left ventricular end-diastolic pressure was raised from zero to 20 mm Hg, the respective transmural pressures increased from 0.2 +/- 0.6 (SD) mm Hg to 2.5 +/- 1.8 mm Hg and from 0.3 +/- 0.7 mm Hg to 6.0 +/- 2.5 mm Hg. Ventricular segmental strain increased by 7.0 +/- 0.8% and 6.0 +/- 0.2%, respectively. No statistically significant differences were found between right ventricular calculated (intracavitary minus pericardial pressure) and measured (open pericardium, open chest) transmural pressures at a given strain, thereby confirming the accuracy of our pericardial pressure measurements.(ABSTRACT TRUNCATED AT 250 WORDS)
Traboulsi
M
M
Department of Medicine, Faculty of Medicine, University of Calgary, Alberta, Canada.
Scott-Douglas
N W
NW
Smith
E R
ER
Tyberg
J V
JV
D000818:Animals; D003187:Compliance; D003971:Diastole / Q000502:physiology; D004285:Dogs; D006352:Heart Ventricles / Q000033:anatomy & histology; D009200:Myocardial Contraction / Q000502:physiology*; D010496:Pericardium / Q000502:physiology*; D011312:Pressure; D016276:Ventricular Function