Asensitivity is expressed as ( y/ x)/(y/x)x100, where y is ps, pd
or sv and x is an independent parameter: determinants of stroke
volume and systolic and diastolic aortic pressure.
Stergiopulos, Nikos, Jean-Jacques Meister, and Nico Westerhof.
Biomedical Engineering Laboratory, Swiss Federal Institute of
Technology, PSE-Ecublens, 1015 Lausanne, Switzerland, Laboratory for
Physiology, Institute for Cardiovascular Research, ICaR-VU, Free
University, Amsterdam, The Netherlands
APStracts 2:0542H, 1995.
We investigated how parameters describing the heart and the arterial
system contribute to the systolic (Ps), diastolic pressure (Pd) and
stroke volume (SV). We have described the heart by the varying
elastance model using 6 parameters and the systemic arterial tree by
the three element windkessel model, leading to a total of 6+3
parameters. Application of dimensional analysis lead to a total of 6
dimensionless parameters describing dimensionless systolic and
diastolic pressures, i.e. pressures with respect to venous pressure
(Ps/Pv and Pd/Pv). Stroke volume (SV) was normalized with respect to
unloaded ventricular volume (Vd). Sensitivity analysis showed that
Ps/Pv Pd/Pv, and SV/Vd could be accurately described by four, three,
and three dimensionless parameters, respectively. With this limited
number of parameters it was then possible to obtain empirical
analytical expressions for Ps/Pv, Pd/Pv and SV/Vd. The analytic
predictions were tested against the model values and found to be as
follows: Ps-predicted = (1.0007 0.0062) Ps, r=0.987, Pd-predicted =
(1.016 0.0085) Pd, r=0.992, and SV-predicted = (0.9987 0.0028) SV,
r=0.996. We conclude that aortic systolic and diastolic pressures and
stroke volume can be accurately described by a limited number of
parameters, and that for any condition of the heart and the arterial
system Ps, Pd and SV can be presented in analytical form.
Received 14 August 1995; accepted in final form 9 November 1995
APS Manuscript Number H763-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95