A cardioverter / defibrillator comprising: a set of conductive electrodes (14, 34) including a number of electrodes (18, 20, 22, 36, 38) yun pot (12, 32) housing a functional circuit wherein: the set of conductive electrodes (14, 34) is coupled to the canister (12, 32) and the functional circuit is configured to perform steps for discriminating between cardiac rhythms of the heart ofa patient (10, 30) to determine those that are appropriate for therapy, including the steps of: receiving several cardiac complexes from said electrodes (18, 20, 22 , 36, 38) get a heartbeat and determine from it whether it is likely an arrhythmia and, if so, cause lassiguientes Estapar: (a) analyzing the cardiac complex using a subsequent first mathematical determination to obtain unprimer result, and comparing the first result to a first threshold to obtain a first Boolean value (B) analyzing said subsequent cardiac complex using a second mathematical determination to obtain unsegundo results, analyzing said second mathematical determination is a variability of correlations of losrecientes of said various cardiac complexes compared to a template, and compare the second resultadocon a second threshold to obtain a second Boolean value (C) performing a first Boolean logic function using the second Boolean value to determine at least ifs needed therapy.Un cardioversor/desfibrilador implantable que comprende: un conjunto de electrodos conductores (14, 34) que incluye un cierto número de electrodos (18, 20, 22, 36, 38) yun bote (12, 32) que aloja un circuito funcional en el que: el conjunto de electrodos conductores (14, 34) está acoplado al bote (12, 32) y el circuito funcional está configurado para realizar etapas para discriminar entre ritmos cardíacos del corazón deun paciente (10, 30) para determinar aquellos que son apropiados para terapia, incluyendo las etapas de:recibir varios complejos cardíacos desde dichos electrodos (18, 20, 22, 36, 38) obtener un latido del corazón y determinar
