Discrepant outcome between myocardial energy-related metabolites and infarct size limitation during retroperfusion of the coronary sinus.

The basic idea of retroperfusion of the coronary sinus (RCS) is to ameliorate detrimental consequences of myocardial ischaemia. Several experimental models of RCS have been introduced, most with an emphasis on functional myocardial status. Since only few studies have been devoted to energy metabolic considerations and none to continuous monitoring of energy-related metabolites of myocardium during RCS, we here present such a study using microdialysis. This study comprised the following components: Coronary occlusion and drainage on the beating heart with RCS-assist (60 min), hypothermic (30 degrees C) extracorporeal circulation (ECC) and cardioplegia (45 min), reperfusion and rewarming to 38 degrees C on ECC (30 min). The microdialysis analytical outcome mainly reflected anaerobic energy metabolism in potentially ischaemic myocardium. Additionally, a pronounced increase of microdialysate content of lactate, pyruvate and guanosine was observed in non-ischaemic myocardium especially during the reperfusion phase. The planimetric calculation revealed an infarct size reduction from 69% to 19% and was not correlated to clear-cut improvements of potentially ischaemic myocardial energy metabolism. We conclude that prolonged (60 min) anaerobic energy metabolism does not pose an immediate threat to cell viability but could even sustain myocyte survival.