The Annals of Thoracic Surgery, Vol 41, 58-64, Copyright © 1986 by The Society of Thoracic Surgeons
Inotropic response of the salvaged myocardium after acute coronary occlusion
LD Berrizbeitia, W Piccione, JC Austin, K Sawtelle, GR Dance, RJ Shemin and LH Cohn
We determined the response of the reperfused myocardium to inotropic
stimulation with dobutamine hydrochloride. The middle part of the left
anterior descending coronary artery (LAD) was occluded in 15 greyhounds for
3 hours. Group 1 (N = 8) was reperfused for 3 hours in the beating, working
heart. Group 2 (N = 7) was put on cardiopulmonary bypass (CPB) for 1 hour,
received 500 ml of potassium cardioplegia in the aortic root and in the
area of ischemia through an internal mammary-LAD graft, and the LAD was
reperfused off CPB for 3 hours. After 3 hours of reperfusion, dobutamine
was given at 10 micrograms/kg/min for 20 minutes. Regional myocardial
function was determined with subendocardial ultrasonic crystals in the area
of ischemia and in the base of the heart; segmental contractility was
determined from the ratio of peak left ventricular pressure to end-systolic
segment length; and global contractility was determined by the slope of the
ventricular pressure wave at a developed pressure of 40 mm Hg. Measurements
were made prior to LAD occlusion (control), at the end of 3 hours of
reperfusion (6 hours from the beginning of occlusion), and after 20 minutes
of dobutamine infusion. Dobutamine infusion improved segmental function in
all animals compared with 3 hours of reperfusion. The study shows that the
reperfused myocardium responds favorably to inotropic stimulation after 3
hours of occlusion and 3 hours of reperfusion, and that the contractile
response both to reperfusion and to inotropic stimulation is greatly
affected by the method of reperfusion.
