Abstract
To evaluate the myocardial protective effects of various cardioplegic infusates, 104 isolated working rat hearts were studied. Following normothermic (37 C) cardioplegic arrest (30 minutes) and hypothermic (21 C) cardioplegic arrest (60 minutes), the recovery course of cardiac function were observed.
At hypothermic condition, St. Thomas'Hospital solution (ST), glucose insulin potassium solution (GIK), lactate Ringer's potassium solution (LRK) showed significantly better restoration of aortic flow than modified Roe's solution. GK solution and Young's solution. ST added GIK solution exhibited the highest and most lasting functional recovery in mean values. On the other hand, simple external cooling, Kirsch's solution, and lactate Ringer's GK solution resulted in marked deterioration of cardiac function. At normothermic condition, ST was significantly superior than LRK. Groups of simple aortic occlusion, GIK and Young's solution followed by GIK could not recover after the reperfusion.
These results indicate that balanced electrolyte solution contained Mg _??_ (ST) may have a superior myocardial preservative action, insulin may present an inotropic effect following global ischemia at hypothermic condition, and excessively hypertonic solution (LRGK, Kirsch) may be damaging to the myocardium. It seems also that perfusion experiment of isolated working rat heart is very useful as a screening test of cardioplegic solutions, because the isolated heart has no extracoronary collateral flow and their net effect on myocardium can be clearly observed.
