AJP - Heart and Circulatory Physiology, Vol 235, Issue 6 690-H700, Copyright © 1978 by American Physiological Society
Volume overload heart failure: length-tension curves, and response to beta-agonists, Ca2+, and glucagon
W. H. Newman
Left ventricular force-generating capacity was determined in 19
anesthetized dogs with heart failure (HF) from aortocaval fistula. At the
time of study all dogs had ascites, edema, and elevated pulmonary wedge
pressure. Length-contractile force (CF) curves recorded from the left
ventricle (LV) with a modified Walton-Brodie arch indicated that the LV was
operating on the ascending limb of the length-CF curve at 62.4 +/- 0.1%
Lmax in the normal group and in the HF group at 83.4 +/- 2.7% Lmax. In HF
the length-CF curve was depressed when compared to normal and was further
depressed when CF in grams was normalized for changes in LV wall thickness
and expressed as g/cm2. Additionally, dose-response curves of CF in
response to injected norepinephrine, isoproterenol, glucagon, and calcium
were depressed when compared to the normal group while the response of
heart rate and blood pressure was not different. These findings indicate
that volume overload HF is associated with depressed ventricular muscle
function and a depressed response to inotropic drugs.
