Postischemic synthesis of high energy phosphates in isolated porcine hearts during reperfusion with 11 or 25°C hypothermic perfluorocarbon emulsion FC 43. A 31P magnetic resonance spectroscopy study

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Abstract
OBJECTIVE: One aim of coronary reperfusion after myocardial ischemia isto restore the myocardial content of high energy phosphates. Thesuperiority of the artificial oxygen carrier perfluorocarbon emulsion FC43over blood solution is known, therefore, in this paper we examined thetemperature-dependence of this substance. METHOD: The changes of the highenergy phosphates phosphocreatine (PCr) and inorganic phosphate (Pi) weredocumented in 29 isolated pig hearts, employing a 4.7 Teslamagnetic-resonance-spectroscope (MRS). After 15 min warm ischemia,reperfusion with warm blood and a cardioplegic ischemia period of 45 min,these hearts were reperfused with either 11 or 25 degrees C hypothermicoxygenated perfluorocarbon emulsion FC43, both under continuousspectroscopy. MRS is able to directly measure PCr as well as Pi. Theirrelation expresses the state of myocardial energy stores. RESULTS:Reperfusion with 11 degrees C hypothermic FC43 (n = 14) caused an increaseof the relation PCr to Pi by a factor of 9, compared to an increase by afactor of 4 with 25 degrees C emulsion (n = 15) (P < 0.05). During 80min of reperfusion with 11 degrees C cold FC43 emulsion the average flowrate was 90 +/- 12 and 96 +/- 11 ml/min during reperfusion with 25 degreesC hypothermic FC43 emulsion. Both rates fell only slightly in the course oftime. CONCLUSION: We conclude that reperfusion with 11 degrees Chypothermic oxygenated FC43 in isolated ischemic porcine hearts leads to aclear increase of the index PCr/Pi compared with reperfusion at 25 degreesC. The correlation between the synthesis of myocardial high energyphosphates with postcardioplegic ventricular function is questionable. Iffurther studies will show an improvement of myocardial function afterperfusion with hypothermic oxygenated perfluorocarbon emulsion FC43, thissolution may find clinical application in the storage of explanted humanhearts for transplantation, during transportation to the recipient.