Jt. Cope et al., INTRAVENOUS PHENYLEPHRINE PRECONDITIONING OF CARDIAC GRAFTS FROM NON-HEART-BEATING DONORS, The Annals of thoracic surgery, 63(6), 1997, pp. 1664-1668
Background. Hypoxia and warm ischemia produce severe injury to cardiac
grafts harvested from non-heart-beating donors. To potentially improv
e recovery of such grafts, we studied the effects of intravenous pheny
lephrine preconditioning. Methods. Thirty-seven blood-perfused rabbit
hearts were studied. Three groups of non-heart-beating donors underwen
t intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7)
, or 50 mu g/kg (n = 7) before initiation of apnea. Non-heart-beating
controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occur
red after 6 to 12 minutes of apnea, followed by 20 minutes of warm in
vivo ischemia. A 45-minute period of ex vivo reperfusion ensued. Nonis
chemic controls (n = 7) were perfused without antecedent hypoxia or is
chemia. Results. Phenylephrine 25 mu g/kg significantly delayed the on
set of hypoxic cardiac arrest compared with saline controls (9.6 +/- 0
.5 versus 7.7 +/- 0.4 minutes; p = 0.00001), yet improved recovery of
left ventricular developed pressure compared with saline controls (57.
1 +/- 5.3 versus 41.0 +/- 3.4 mm Hg; p = 0.04). Phenylephrine 25 mu g/
kg also yielded a trend toward less myocardial edema than saline vehic
le (p = 0.09). Conclusions. Functional recovery of nonbeating cardiac
grafts is improved by preconditioning. We provide evidence that the my
ocardium can be preconditioned with phenylephrine against hypoxic card
iac arrest. (C) 1997 by The Society of Thoracic Surgeons.