Effects of initial reperfusion temperature and pressure after prolonged cardioplegic ischemic arrest. A metabolic and functional study in rat hearts.

The effects of temperature and pressure during early cardiac reperfusion after 3.5 hours of hypothermic, cardioplegic ischemia were investigated in isolated Langendorff-perfused rat hearts. The hearts were randomized in two groups and subjected to different techniques of reperfusion. The group I hearts were exposed to rapidly rising perfusion pressure and temperature, and in group II slowly rising pressure and temperature were employed. After 60 min of reperfusion, left ventricular developed pressure, coronary flow and tissue content of high-energy phosphates were evaluated. Left ventricular pressure and coronary flow were significantly better preserved in group II. Recovery of adenosine triphosphate and creatine phosphate was significantly lower in group I (5.27 +/- 0.38 and 8.72 +/- 0.62 mumol x g dry weight-1) than in group II (9.31 +/- 0.41 and 14.97 +/- 0.62). The study thus demonstrated that functional recovery, restoration of coronary flow and normalization of high-energy phosphate stores after long periods of hypothermic cardioplegic ischemia can be considerably influenced by the employed reperfusion technique.