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-heartbeating donors. To potentially improve recovery of such grafts, we studied the effects of intravenous phenylephrine preconditioning.


METHODS
Thirty-seven blood-perfused rabbit hearts were studied. Three groups of non-heart-beating donors underwent intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7), or 50 microg/kg (n = 7) before initiation of apnea. Non-heart-beating controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occurred 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. Nonischemic controls (n = 7) were perfused without antecedent hypoxia or ischemia.


RESULTS
Phenylephrine 25 microg/kg significantly delayed the onset 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 microg/kg also yielded a trend toward less myocardial edema than saline vehicle (p = 0.09).


CONCLUSIONS
Functional recovery of nonbeating cardiac grafts is improved by preconditioning. We provide evidence that the myocardium can be preconditioned with phenylephrine against hypoxic cardiac arrest.
Cope
J T
JT
Department of Surgery, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
Mauney
M C
MC
Banks
D
D
Binns
O A
OA
Moore
C L
CL
Rentz
J J
JJ
Shockey
K S
KS
King
R C
RC
Kron
I L
IL
Tribble
C G
CG
D000704:Analysis of Variance; D000818:Animals; D001834:Body Water / Q000378:metabolism; D006323:Heart Arrest / Q000601:surgery*; D016027:Heart Transplantation / Q000379:methods*; D007262:Infusions, Intravenous; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D017202:Myocardial Ischemia / Q000601:surgery; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption; D010656:Phenylephrine / Q000008:administration & dosage*; D011817:Rabbits; D016277:Ventricular Function, Left
D010656:Phenylephrine