Abstract: An apparatus and method for the detection and treatment of arrhythmias using a processor having a neural network with a hierarchical arrangement including a first lower level for classifying individual waveforms, a second higher level for diagnosing detected arrhythmias and a third higher level for the application of therapy in response to a diagnosed arrhythmia. The neural network may be a back propogation neural network or an associative memory type neural network. The arrhythmias detected may be at least one of bradycardia, tachycardia and fibrillation. The apparatus may include a cardioverting/defibrillating pacemaker. In general, the apparatus acquires physiological signals representative of heart activity in a patient. A neural network receives the physiological signals and determines if any arrhythmia is present, and if present, selects therapy to be applied to the heart. A therapy generator then applies the therapy selected by the neural network.