The Annals of Thoracic Surgery, Vol 31, 144-154, Copyright © 1981 by The Society of Thoracic Surgeons
Intraaortic balloon counterpulsation: its influence alone and combined with various pharmacological agents on regional myocardial blood flow during experimental acute coronary occlusion
GK Jett, SK Dengle, PA Barnett, MR Platt, JT Willerson, JT Watson and RC Eberhart
We investigated the separate and combined effects of pharmacological and
intraaortic balloon pump (IABP) support on regional myocardial blood flow
in an experimental model of acute myocardial ischemia.
Chloralose-anesthetized dogs were ventilated with an oxygen-air mixture,
and cardiac output, arterial pressure, and heart rate were held constant.
Treatment was begun 20 minutes following permanent ligation of the left
anterior descending coronary artery (LAD). We evaluated the following
pharmacological interventions: 25% hypertonic mannitol, isosorbide
dinitrate, methyl-prednisolone sodium succinate, and propranolol. We
measured left ventricular hemodynamics and intramyocardial blood flow by
the radioactive microsphere technique prior to treatment and at 15-minute
intervals thereafter. Compared with control measurements 20 minutes
following LAD ligation, collateral blood flow to ischemic myocardium tended
to decrease with no treatment. Treatments with the four pharmacological
interventions and with IABP alone produced no significant improvement in
collateral blood flow to ischemic myocardium 15 minutes following
treatment. In contrast, mannitol, isosorbide dinitrate, and propranolol,
each combined with IABP support, produced significant improvements in
collateral flow within the same time periods. In nonischemic myocardium,
combined pharmacological and IABP treatment did not enhance myocardial
blood flow above that obtained with the pharmacological agents alone. The
most effective combination of mechanisms for improving the ischemic
region's myocardial blood flow appeared to be a reduction of extravascular
coronary flow resistance coupled with a simultaneous increase in diastolic
arterial pressure.