The continuity of consciousness

After reading George Ritchie's 1979 book Return From Tomorrow, a psychiatrist's account of his own Near-Death Experience (NDE)... I started to ask patients who had survived a cardiac arrest if they had memories from their period of unconsciousness. Within two years, 12 patients out of 50 survivors of cardiac arrest told me about their NDE. That piqued my scientific curiosity. According to our current medical concepts, it is not possible to experience consciousness during a cardiac arrest. Those