AJP - Heart and Circulatory Physiology, Vol 246, Issue 3 435-H447, Copyright © 1984 by American Physiological Society
Mechanical determinants of transient changes in stroke volume
B. K. Slinker, K. B. Campbell, J. A. Ringo, P. A. Klavano, J. D. Robinette and J. E. Alexander
To better define beat-to-beat regulation of stroke volume (SV), the
several-beat transient response of the left ventricle (LV) to sudden
changes in hydraulic loading impedance was studied. Data were collected
from eight canine isolated heart-lung preparations with controlled LV
loading impedance. At a selected diastolic interval, a sudden increase in
hydraulic loading resistance was induced. The resulting transient response
in SV, end-diastolic pressure (EDP), and end-systolic pressure (ESP) was
analyzed by comparing the relative predictive capability of six competing
models, each incorporating different degrees of complexity in the
relationship between SV and EDP and ESP. The basic model assumed linear LV
pressure-volume relationships at both end diastole and end systole.
Incorporation of nonlinear, end-state interaction or coronary perfusion
pressure effects into the basic model did not improve predictive
performance. Models incorporating SV and ESP of the preceding beat as well
as ejecting beat ESP and EDP were consistently superior to all other
models. The ranking of the relative influence of the determinants of SV was
1) ejecting beat ESP, 2) preceding beat ESP, 3) ejecting beat EDP, and 4)
preceding beat SV.
