The Annals of Thoracic Surgery, Vol 38, 108-116, Copyright © 1984 by The Society of Thoracic Surgeons
Norepinephrine plus phentolamine improves regional blood flow during experimental low cardiac output syndrome
JH Lemmer, MJ Botham, P McKenney, RA Gerren, MM Kirsh and KP Gallagher
A complication of cardiac surgical procedures is postoperative low cardiac
output syndrome. Treatment with norepinephrine plus phentolamine (N + P) is
beneficial, but the effect of these agents on regional organ blood flow has
not been evaluated. Therefore, in 6 dogs with long-term instrumentation,
pentobarbital was infused to simulate low cardiac output (32 + 10% of the
conscious control level). Infusions of N + P at 0.2, 0.5, and 1.0
microgram/kg/min restored cardiac pump performance to conscious control
levels. Regional blood flows, determined with tracer-labeled microspheres,
were substantially reduced in the low cardiac output state but increased to
values not markedly different from control levels in all organs studied
except stomach fundus during infusion of N + P. The pressure-work index, an
indirect measure of myocardial oxygen consumption, did not increase to more
than the conscious level except at the highest dose. The data demonstrate
that simultaneous infusion of N and P is capable of successfully improving
cardiac pump performance with restoration of vital organ perfusion and
without evidence of excessive myocardial oxygen consumption.
