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 ameliora te detrimental consequences of myocardial ischaemia. Several experimental m odels of RCS have been introduced. most with an emphasis on functional myoc ardial status. Since only few studies have been devoted to energy metabolic considerations and none to continuous monitoring of energy-related metabol ites of myocardium during RCS. we here present such a study using microdial ysis. This study comprised the following components: Coronary occlusion and drainage on the beating heart with RCS-assist (60 min), hypothermic (30 de greesC) extracorporeal circulation (ECC) and cardioplegia (45 min), reperfu sion and rewarming to 38 degreesC on ECC (30 min). The microdialysis analyt ical outcome mainly reflected anaerobic energy metabolism in potentially is chaemic myocardium. Additionally, a pronounced increase of microdialysate c ontent of lactate, pyruvate and guanosine was observed in non-ischaemic myo cardium especially during the reperfusion phase. The planimetric calculatio n revealed an infarct size reduction from 69% to 19% and was not correlated to clear-cut improvements of potentially ischaemic myocardial energy metab olism. We conclude that prolonged (60 min) anaerobic energy metabolism does not pose an immediate threat to cell viability but could even sustain myoc yte survival.