INTRAVENOUS PHENYLEPHRINE PRECONDITIONING OF CARDIAC GRAFTS FROM NON-HEART-BEATING DONORS

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.