POSTISCHEMIC SYNTHESIS OF HIGH-ENERGY PHOSPHATES IN ISOLATED PORCINE HEARTS DURING REPERFUSION WITH 11 OR 25-DEGREES-C HYPOTHERMIC PERFLUOROCARBON EMULSION FC-43 - A P-31 MAGNETIC-RESONANCE SPECTROSCOPY STUDY

Objective: One aim of coronary reperfusion after myocardial ischemia i s to restore the myocardial content of high energy phosphates. The sup eriority of the artificial oxygen carrier perfluorocarbon emulsion FC4 3 over blood solution is known, therefore, in this paper we examined t he temperature-dependence of this substance. Method: The changes of th e high energy phosphates phosphocreatine (PCr) and inorganic phosphate (Pi) were documented in 29 isolated, pig hearts, employing a 4.7 Tesl a magnetic-resonance-spectroscope (MRS). After 15 min warm ischemia, r eperfusion with warm blood and a cardioplegic ischemia period of 45 mi n, these hearts were reperfused with either 11 or 25 degrees C hypothe rmic oxygenated perfluorocarbon emulsion FC43, both under continuous s pectroscopy. MRS is able to directly measure PCr as well as Pi. Their relation expresses the state of myocardial energy stores, Results: Rep erfusion with 11 degrees C hypothermic FC43 (n=14) caused an increase of the relation PCr to Pi by a factor of 9, compared to an increase by a factor of 4 with 25 degrees C emulsion (n=15) (P <0.05). During 80 min of reperfusion with 11 degrees C cold FC43 emulsion the average fl ow rate was 90+/-12 and 96+/-11 ml/min during reperfusion with 25 degr ees C hypothermic FC43 emulsion. Both rates fell only slightly in the course of time. Conclusion: Ne conclude that reperfusion with 11 degre es C hypothermic oxygenated FC43 in isolated ischemic porcine hearts l eads to a clear increase of the index PCr/Pi compared with reperfusion al 25 degrees C. The correlation between the synthesis of myocardial high energy phosphates with postcardioplegic ventricular function is q uestionable. If further studies will shaw an improvement of myocardial function after perfusion with hypothermic oxygenated perfluorocarbon emulsion FC43, this solution may find clinical application in the stor age of explanted human hearts for transplantation, during transportati on to the recipient. (C) 1997 Elsevier Science B.V.