AJP - Heart and Circulatory Physiology, Vol 267, Issue 5 1895-H1906, Copyright © 1994 by American Physiological Society
Determinants of end-systolic pressure during different load alterations in the in situ left ventricle
L. P. van der Linden, E. T. van der Velde, H. C. van Houwelingen, A. V. Bruschke and J. Baan
Department of Cardiology, University of Leiden, The Netherlands.
Because of the strong dependency of the end-systolic pressure-volume
relation on the type of transient loading intervention in the in situ left
ventricle (LV), experiments in the basal inotropic state in 16 open-chest
anesthetized dogs were reanalyzed to find additional variables to model and
predict end-systolic pressure (ESP) of both afterloading and preloading
interventions by a single equation. Random-coefficients regression analysis
was performed on 22 experiments in the basal inotropic state
simultaneously, yielding an overall R2 of 0.97. The major part of total
variance of ESP was due to linear terms of end-systolic volume (ESV) (74%)
and stroke volume (SV) (19%). The SV effect was consistently negative and
quantitatively quite important. An average load-independent end-systolic
elastance of 6.7 mmHg/ml and an average SV effect of -5.7 mmHg/ml ejected
were estimated, separating the "force-length" property from shortening
effects in the in situ LV. History-related effects appeared to be only
minor.
