Objective: To characterize two porcine models of cardiac arrest: ventricular fibrillation cardiac arrest (VFCA) and asphyxiation cardiac arrest (ACA).Design and Methods: Thirty-two pigs were randomized into two groups.The VFCA group (n=16) were subject to programmed electrical stimulation and the ACA group (n=16) underwent endotracheal tube clamping to induce CA.Once induced, CA remained untreated for a period of 8 minutes.Two minutes following initiation of cardiopulmonary resuscitation (CPR), defibrillation was attempted until return of spontaneous circulation (ROSC) was achieved or animals died.Results: ROSC was 100% successful in VFCA and 50% successful in ACA.CPR duration in VFCA was about half as short as in ACA.The survival time of VFCA was significantly longer than for ACA.VFCA had better mean arterial pressure and cardiac output after ROSC than ACA.Arterial blood gas analysis indicated more detrimental metabolic disturbances in ACA compared with VFCA.Myocardial metabolism imaging using Positron Emission Tomography demonstrated that myocardial injuries after ACA were more severe and widespread than after VFCA.Lower contents of myocardial energy metabolism enzymes (Na+-K+-ATPase enzyme activity, Ca2+-ATPase enzyme activity, superoxide dismutase and phosphodiesterase) were found in ACA relative to VFCA.By comparison, the overall heart morphologic structure and the mitochondrial crista structure were less severely injured in the VFCA group than that in the ACA group.Conclusions: Compared with VFCA, ACA causes more severe cardiac dysfunction, myocardium injury and metabolism hindrance associated with less successful resuscitation and shorter survival time; therefore they should be treated as different pathological entities.