Comparison of myocardial metabolism by using PET after resuscitation between ventricular fibrillation cardiac arrest and asphyxia cardiac arrest

Abstract

Objective To characterize myocardial metabolism using positron emission tomography (PET) in porcine models of ventricular fibrillation cardiac arrest (VFCA) and asphyxiation cardiac arrest (ACA) after resuscitation. Methods Thirty-two healthy miniature pigs were randomized into two groups. The pigs of VFCA group (n=16) were subject to programmed electric stimulation to create a ventricular fibrillation cardiac arrest, and the pigs of ACA group (n=16) were subjected to endotracheal tube clamping to establish a cardiac arrest (CA). Once modeling was established, pigs with CA were left untreated for a period of 8 min. Two minutes following initiation of cardiopulmonary resuscitation (CPR), defibrillation was attempted until the restoration of spontaneous circulation (ROSC) was achieved or animals died. To assess myocardial metabolism, PET was performed before modeling, 4 hrs and 24hrs after ROSC. To analyze 18F-FDG myocardial uptake in PET, the maximum standardized uptake value (SUVmax) ) was measured. Results ROSC was obtained in 100% of pigs in VFCA group and only 50% in ACA group. The average survival time in VFCA pigs was significantly longer than that in ACA pigs (22.63±0.95) hvs. (8.75±2.54)h, P<0.01. VFCA pigs had better mean arterial pressure and cardiac output after ROSC than ACA pigs. Myocardial metabolism imaging using PET demonstrated that myocardial metabolism injuries after ACA were more severe and widespread than those after VFCA at 4 hrs and 24hrs after ROSC and SUVmax) was much higher in VFCA group than that in ACA group [4 h after ROSC: (1.9±0.3) vs. (1.0±0.4), P<0.01; 24 h after ROSC: (2.4±0.6) vs. (1.2±0.5), P<0.01]. Conclusions Compared with VFCA, ACA causes more severe cardiac metabolism dysfunction associated with less successful resuscitation and shorter survival time; therefore they should be treated as different pathological entities. Key words: Ventricular fibrillation; Asphyxia; Cardiac arrest; Return of spontaneous circulation; Myocardial metabolism; PET; Maxinum standardized uptake value; Survival time