Depletion of myocardial adenosine triphosphate during prolonged untreated ventricular fibrillation: effect on defibrillation success

We studied left ventricular endomyocardial adenosine triphospate levels in 13 large mongrel dogs before and during ventricular fibrillation induced cardiac arrest to assess whether myocardial adenosine triphosphate content could predict successful cardiopulmonary resuscitation. Endomyocardial biopsies were performed during sinus rhythm (control), after 15 min of ventricular fibrillation or 10 min of ventricular fibrillation and 5 min of open chest cardiopulmonary resuscitation, after 20 min of ventricular fibrillation and 10 min of open chest cardiopulmonary resuscitation and after 40 min ventricular fibrillation and 15-20 min open chest cardiopulmonary resuscitation. Myocardial adenosine triphosphate was measured utilizing a bioluminescence method adapted for use with endomyocardial biopsies and normalized to protein content. Left ventricular endomyocardial adenosine triphosphate content fell significantly over time from a control level of 8.88 ±0.9 pg/mg protein to 5.73 ± 0.5 pg/mg protein at 15 min of cardiac arrest, to 3.4 ± 0.4 μg/mg protein after 30 min of cardiac arrest and to 1.98 ± 0.3 μg/mg protein after 60 min of cardiac arrest (P < 0.001). Adenosine triphosphate levels were significantly different between animals that received 10 min of ventricular fibrillation and successful open chest cardiopulmonary resuscitation and those that received 40 min of ventricular fibrillation and unsuccessful open chest cardiopulmonary resuscitation (4.35 ± 0.48 vs. 2.11 ± 0.43 μg/mg protein; P < 0.025). Endomyocardial adenosine triphosphate levels falling below 3.5 μg/mg protein were associated with only 2/6 animals being successfully resuscitated, while 6/7 successfully resuscitated animals had adenosine triphosphate levels ≥ 3.5 μg/ mg protein (Positive Predictive Value = 0.75, Negative Predictive Value = 0.80). Myocardial adenosine triphosphate content diminishes significantly during prolonged ventricular fibrillation and once levels fall below 3.5 μg/mg protein, successful resuscitation is rare.