Effect of cardiopulmonary resuscitation on restoration of myocardial ATP in prolonged ventricular fibrillation

Abstract

Background: It is known that a short period of cardiopulmonary resuscitation (CPR) prior to defibrillation improves survival in patients with unwitnessed sudden collapse. However, there has been no report about whether CPR restores myocardial adenosine triphosphate (ATP) during prolonged ventricular fibrillation (VF). The aim of this study is to investigate the effect of CPR in restoring of myocardial high energy phosphate during prolonged VF.Methods: Seventy two adult male Sprague-Dawley rats (330-400 g) were enrolled in the study. Baseline ATP and ADP prior to induction of VF were measured from 9 animals (No-VF group). Sixty three animals were subjected to 4 minutes of untreated VF. Then, animals were randomized into No-CPR group (n=37) and CPR group (n=26). In No-CPR group, ATPs and ADPs were measured 4 (No-CPR4, n=9), 6 (No-CPR6, n=10), 8 (No-CPR8, n=8), or 10 (No-CPR10, n=10) minutes after induction of VF, respectively. CPR group received 2 (CPR2, n=10), 4 (CPR4, n=8), or 6 (CPR6, n=8) minutes of mechanical chest compressions, respectively.Results: Myocardial ATP (nmol/mg•protein) and ATP/ADP ratio in No-VF group was 5.49±1.71 and 0.23±0.12. Myocardial ATP in No-CPR group decreased as duration of VF was prolonged (4.27±1.58 in No-CPR4, 4.13±1.31 in No-CPR6, 3.77±1.42 in No-CPR8, and 3.52±0.90 in No-CPR10, respectively; p<0.05 between No-CPR8 and No-CPR10 vs. No-VF group). Myocardial ATP in CPR2 was not different compared to No-VF group. However, myocardial ATP decreased as CPR time was prolonged than 2 minutes (5.27±1.67 in CPR2, 3.77±1.05 in CPR4, and 3.49±1.08 in CPR6, respectively; p<0.05 between CPR4 and CPR6 vs. no-VF group). Myocardial ATP/ADP ratio in No-CPR group tended to be lower (0.13±0.05 in No-CPR4, 0.15±0.04 in No-CPR6, 0.17±0.06 in No-CPR8, and 0.17±0.05 in No-CPR10, respectively) than No-VF group. Myocardial ATP/ADP ratio in CPR2 increased to the level of No-VF group and tended to decrease as CPR time was prolonged (0.26±0.15 in CPR2, 0.20±0.09 in CPR4, and 0.19±0.03 in CPR6, respectively).Conclusion: Myocardial ATP decreases as duration of ventricular fibrillation is prolonged. Cardiopulmonary resuscitation for 2 minutes after prolonged ventricular fibrillation restores myocardial ATP.