The Annals of Thoracic Surgery, Vol 44, 66-72, Copyright © 1987 by The Society of Thoracic Surgeons
Surgical revascularization of acute evolving myocardial infarction without blood cardioplegia fails to restore postischemic function in the involved segment
J Vinten-Johansen, KB Faust, SA Mills and AR Cordell
This study determines the additional protection provided by multidose
hypothermic potassium blood cardioplegia over cardiopulmonary bypass alone
following one hour of coronary occlusion. In 19 anesthetized dogs having an
open-chest procedure, the left anterior descending coronary artery (LAD)
was occluded for one hour, and this resulted in loss of active shortening
in the affected zone (sonomicrometry). Cardiopulmonary bypass was
established, and the dogs were divided into two groups based on the mode of
reperfusion. In 10 dogs, hearts were arrested for one hour with amino
acid-enhanced multi-dose blood cardioplegia; the ligatures were removed
prior to the second infusion. In the 9 remaining dogs, the ligatures were
removed and reperfusion was initiated with unmodified blood on total vented
bypass. Both groups were reperfused for one additional hour. Postischemic
levels of adenosine triphosphate (ATP) were comparable in the blood
cardioplegia and bypass groups, and subendocardial levels averaged 42.8%
and 45.8% of controls, respectively. Levels of creatine phosphate returned
to control values. Subendocardial water content was significantly less in
the blood cardioplegia hearts than the bypass hearts (79.4 +/- 0.5% vs.
81.5 +/- 0.5%; p less than .05); subendocardial water content in the blood
cardioplegia group was not different from controls (78.6 +/- 0.1%). Blood
cardioplegia restored significantly more fractional shortening than total
vented bypass alone (39.3 +/- 9.8% vs. 6.3 +/- 9.1% of control), despite
similarities in postischemic levels of ATP. We conclude that blood
cardioplegia allows better myocardial salvage in the setting of evolving
infarction. Therefore, attention must be directed to both the conditions
(bypass, delivery pressure) and composition (cardioplegia) of reperfusion.