The Annals of Thoracic Surgery, Vol 22, 50-57, Copyright © 1976 by The Society of Thoracic Surgeons
A comparison of the hemodynamic effects of inotropic agents
LC Argenta, MM Kirsh, EL Bove, VM Cimmino, B Lucchesi, J Straker, R Baker, R Lee and H Sloan
This experimental study was conducted to compare and contrast the
cardiovascular effects of the drugs most commonly used to alleviate low-
cardiac-output syndrome. Twenty-five adult mongrel dogs were infused with
sodium pentobarbital (60 mg/min) until their cardiac output fell to 50+/-5%
of the average control values determined by thermodilution technique prior
to pentobarbital infusion. The dogs were then divided into six groups, and
one of the following agents or combinations of agents was administered to
each group: isoproterenol, glucagon, dopamine, dobutamine, levarterenol and
phentolamine, or levarterenol and nitroprusside. All drugs, except for
glucagon and the combination of levarterenol and nitroprusside, produced an
increase in cardiac output above the nonfailure baseline values. However,
this increase was accompanied by an undesirable, pronounced tachycardia
except when levarterenol was used simultaneously with phentolamine. Both
dopamine and the combined infusion of levarterenol and phentolamine proved
the most effective in restoring systemic arterial pressure to near baseline
values, and both were able to increase renal blood flow above the failure
baseline values. While renal blood flow remained elevated with all dosages
of levarterenol and phentolamine, it tended to decrease with larger doses
of dopamine. These experiments demonstrate that there are major advantages
in the use of simultaneously infused levarterenol and phentolamine for
control of low-cardiac-output syndrome: increased cardiac output without
elevated peripheral vascular resistance, restoration of systemic arterial
pressure and consequent improved coronary flow, absence of tachycardia, and
augmented renal blood flow.
