Increased ventricular contractility is not sufficient for effective
positive inotropic intervention.
Binkley, Philip F., Douglas B. Van Fossen, Garrie J. Haas, Carl V.
Leier, James W. Overstreet,.
The Ohio State University, Division of Cardiology, Department
APStracts 3:0039H, 1996.
Positive inotropic intervention with dobutamine in patients with
congestive heart failure is accompanied by complementary vascular
changes, as measured by the aortic input impedance spectrum, which
promote the efficient transfer of augmented myocardial contractile
power. It is unknown whether this is a nonspecific response to
increased ventricular contractility or is a function of the
properties of the positive inotropic agent employed. Therefore, the
influence of two different positive inotropic interventions,
dobutamine and dopamine, on ventricular-vascular coupling was
examined in 15 patients with congestive heart failure. Significant
reductions in characteristic aortic impedance, wave reflection, and
low frequency impedance moduli were noted with dobutamine and were
not seen with dopamine. Consequently, a significantly (p=.0008)
greater increase in pulsatile, rather than steady state, power output
was noted with dopamine which was reflective of a significantly
diminished efficiency of power transfer. Therefore, optimal transfer
of increased ventricular contractile power in patients having
congestive heart failure requires increases in large vessel
compliance and complementary changes in ventriculoarterial coupling.
Received 21 September 1995; accepted in final form 2 January
1996.
APS Manuscript Number H897-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 January 96