Evaluation of myocardial preservation using 31P NMR.
The purpose of this study was (1) to monitor myocardial high-energy phosphate content and recovery of left ventricular (LV) contractile function following normothermic graded cardiac ischemia and single-dose hypothermic potassium cardioplegia, and (2) to assess the temporal limits of LV functional recovery during single-dose cardioplegia maintained at 17 degrees C. Rabbit hearts (30) were perfused, equipped with an LV balloon, paced at 240 beats/min, and placed in a nuclear magnetic resonance (NMR) magnet. Hearts underwent either graded, global normothermic ischemia or potassium cardioplegia arrest maintained at 17 degrees C for 1 hr. Myocardial high-energy phosphate level, LV contractility, and temperature were monitored continuously. Phosphocreatine (PCr) fell to 10 +/- 2, 2 +/- 1, and 0% of control and ATP to 70 +/- 3, 19 +/- 7, and 0% of control at 10, 40, and 60 min of 37 degrees C ischemia. After 1 hr of reperfusion, regression analysis of final developed pressure (DP) on end ischemic ATP (EIATP) content revealed: DP = 1.02 EIATP + 18 (r = 0.95). Following single-dose cardioplegia, maintained at 17 degrees C, PCr fell to 16 +/- 3% of control at 60 min while ATP fell only to 92 +/- 5% control. With reperfusion, recovery of DP was 100%. It was concluded that (1) PCr serves as an energy buffer for ATP, (2) EIATP predicts recovery of LV function, (3) single-dose cardioplegia maintained at 17 degrees C provides complete myocardial preservation for up to 60 min.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003327:Coronary Disease / Q000378:metabolism / Q000503:physiopathology; D005069:Evaluation Studies as Topic; D006321:Heart / Q000503:physiopathology; D006352:Heart Ventricles; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D009206:Myocardium / Q000378:metabolism; D009926:Organ Preservation; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D010758:Phosphorus; D011817:Rabbits
D010710:Phosphates; D010725:Phosphocreatine; D010758:Phosphorus; D000255:Adenosine Triphosphate