The Annals of Thoracic Surgery, Vol 52, 949-954, Copyright © 1991 by The Society of Thoracic Surgeons
Myocardial oxygen consumption after fibrillation in the nonhypertrophied porcine ventricle
IB Krukenkamp and S Levitsky
Department of Surgery, Harvard Medical School, New England Deaconess Hospital, Boston, Massachusetts 02215.
Prior studies of nonischemic ventricular fibrillation have identified
variable bioenergetic defects that depend on the prevailing frequency of
electrical activation, coronary perfusion pressure, and left ventricular
wall tension. In hearts in the adequately perfused, vented, and
nondistended state the myocardial oxygen consumption of ventricular
fibrillation may not be significantly different than that of the empty,
beating heart. Thus, the present study investigated both global
normothermic ischemic and nonischemic prolonged ventricular fibrillation
effects on cardiac energetics when quantitated in the same heart under
constant and defined nonworking conditions. At constant heart rate and
perfusion pressure, preload recruitable stroke work was preserved in the
nonischemic group but depressed to 41% of control postischemically (p =
0.018). Under control conditions, no significant differences in myocardial
oxygen consumption between the various nonworking cardiac states were
detected. However, postischemic empty, beating hearts and empty,
fibrillating hearts both extracted (31%) and consumed (26%) less oxygen (p
less than 0.03 each) without concomitant coronary hyperemia. Prolonged
nonischemic ventricular fibrillation increased coronary blood flow 158% (p
less than 0.03) without augmenting myocardial oxygen consumption. These
data contrast with the previously reported increased oxygen demand of
ventricular fibrillation and suggest that postischemic fibrillation is not
bioenergetically deleterious in the nonhypertrophied heart under controlled
working conditions.
