Controlled reperfusion of cardiac grafts from non-heart-beating donors.
BACKGROUND
Hearts harvested from non-heart-beating donors sustain severe injury during procurement and implantation, mandating interventions to preserve their function. We tested the hypothesis that limiting oxygen delivery during initial reperfusion of such hearts would reduce free-radical injury.


METHODS
Rabbits sustained hypoxic arrest after ventilatory withdrawal, followed by 20 minutes of in vivo ischemia. Hearts were excised and reperfused with blood under conditions of high arterial oxygen tension (PaO2) (approximately 400 mm Hg), low PaO2 (approximately 60 to 70 mm Hg), high pressure (80 mm Hg), and low pressure (40 mm Hg), with or without free-radical scavenger infusion. Non-heart-beating donor groups were defined by the initial reperfusion conditions: high PaO2/ high pressure (n = 8), low PaO2/high pressure (n = 7), high PaO2/low pressure (n = 8), low PaO2/low pressure (n = 7), and high PaO2/high pressure/free-radical scavenger infusion (n = 7).


RESULTS
After 45 minutes of reperfusion, low PaO2/ high pressure and high PaO2/low pressure had a significantly higher left ventricular developed pressure (63.6 +/- 5.6 and 63.1 +/- 5.6 mm Hg, respectively) than high PaO2/high pressure (40.9 +/- 4.5 mm Hg; p < 0.0000001 versus both). However, high PaO2/high pressure/free-radical scavenger infusion displayed only a trend toward improved ventricular recovery compared with high PaO2/ high pressure.


CONCLUSIONS
Initially reperfusing nonbeating cardiac grafts at low PaO2 or low pressure improves recovery, but may involve mechanisms other than decreased free-radical injury.
Department of Surgery, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
J T
JT
Cope
M C
MC
Mauney
D
D
Banks
O A
OA
Binns
N F
NF
De Lima
S A
SA
Buchanan
K S
KS
Shockey
S W
SW
Wilson
I L
IL
Kron
C G
CG
Tribble
D000818:Animals; D001784:Blood Gas Analysis; D004195:Disease Models, Animal; D005260:Female; D016166:Free Radical Scavengers / Q000627:therapeutic use; D006323:Heart Arrest / Q000378:metabolism*; D016027:Heart Transplantation; D008297:Male; D015425:Myocardial Reperfusion / Q000379:methods*; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D011817:Rabbits; D013997:Time Factors; D008625:Tiopronin / Q000627:therapeutic use; D014021:Tissue Preservation / Q000379:methods*; D017725:Ventricular Pressure
D016166:Free Radical Scavengers; D008625:Tiopronin; D010100:Oxygen