ABSTRACT
Recovery of myocardial high-energy phosphate (HEP) metabolism after coronary occlusion and reperfusion may vary with ischemic duration and may provide information about the extent of tissue viability. To evaluate the differences between varying durations of ischemia and to attempt to identify metabolic indexes of salvaged viable tissue, intact New Zealand white rabbits underwent either 30 (group 1; n = 8) or 60 (group 2; n = 8) minutes of coronary occlusion followed by reperfusion. HEP metabolism was evaluated with cardiac gated phosphorus 31 (31P) nuclear magnetic resonance (NMR) spectroscopy with a 2.0 T spectrometer. While similar HEP changes were observed during ischemia in both groups, differences in HEP recovery between groups were seen following reperfusion. Group 1 animals demonstrated a gradual decrease in inorganic phosphates (Pi) (p less than 0.05 versus group 2), an immediate recovery of phosphocreatine (PCr) (p = ns versus baseline), and a gradual increase of adenosine triphosphate (ATP) to pre-ischemic levels. Group 2 animals had elevated levels of Pi (p less than 0.05 versus baseline; p less than 0.05 versus group 1), slow recovery of PCr, and continued reduction of ATP (p less than 0.05 versus baseline; p less than 0.05 versus group 1). Group 1 rabbits had a greater extent of viable myocardium than group 2 (77.1 +/- 9.7% of risk area versus 39.4 +/- 9.4%; p less than 0.001). Significant correlations were found between PCr and Pi reperfusion values and myocardial viability (r = 0.59, p less than 0.05; r = 0.73, p less than 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
