RECOVERY OF LEFT-VENTRICULAR FUNCTION AFTER GRADED CARDIAC ISCHEMIA AS PREDICTED BY MYOCARDIAL P-31 NUCLEAR MAGNETIC-RESONANCE

Google Scholar
  • 1 January 1985
    • journal article
    • research article
    • Vol. 97  (4) , 428-435
Abstract
The aim of this study was to determine noninvasively some critical level of high-energy phosphate stores that relates to the recovery of ventricular contractile function after graded cardiac ischemia. Rabbit hearts (n = 30) were equipped with an intraventricular balloon to monitor developed pressure and .+-. dp/dt and placed in a nuclear magnetic resonance magnet (Bruker, 4.7 Tesla). Each heart underwent 10, 20, 40 or 60 min of global ischemia followed by 1 h of reperfusion. The pH as determined by nuclear magnetic resonance dropped from 7.14 .+-. 0.04 to 7.07 .+-. 0.07 (P < 0.02) at 1 min and to 6.19 .+-. 0.08 at 30 min of ischemia; pH ceased to fall thereafter. Phosphocreatine was depleted to 10% .+-. 7% of its preischemic control in 10 min. ATP concentrations were 71% .+-. 14% and 1% .+-. 2% at 10 and 60 min. Regression analysis of recovered developed pressure on end-ischemic ATP (EIATP) revealed: developed pressure = 0.93 (EIATP) + 23 (r2 = 0.99). Anaerobic metabolism as evidenced by a fall in pH appears to be active for 30 min after normothermic ischemia and then ceases. Phosphocreatine buffers the fall in ATP during early ischemia. There is a tight correlation between EIATP and recovery of left ventricular contractile function with a threshold content of approximately 80% below which recovery of function will not be complete.