AJP - Regulatory, Integrative and Comparative Physiology, Vol 237, Issue 3 225-R231, Copyright © 1979 by American Physiological Society
Rate of generation of myocardial power density normalized by cardiac frequency
A. H. Moreno, M. E. Bloomfield and E. A. Grossi
We introduce a frequency normalized, power averaged, rate of generation of
power density (FARPD) that extends the range of applicability of the
averaged rate of generation of power density (ARPD) to any cardiac
frequency encountered in experimental or clinical situations. Normalization
eliminates the frequency-dependent mathematical artifacts arising during
the computation of quantities containing time derivatives of the pressure,
while preserving the effects of changes in heart rate on the cardiac muscle
itself (Bowditch type of phenomena). The distribution of normal values in a
group of 51 control dogs was very close to the standard normal
distribution. These values had no statistically significant differences
with those of a smaller control group studied by independent investigators.
Isoproterenol and propranolol produced highly significant statistical
changes in FARPD. Alterations in pre- and afterload produced changes that
were not significant for the former and significant at the 5% level for the
latter. These changes were small when compared to those resulting from
typical inotropic interventions.
