1. A method for discriminating between cardiac rhythms in mammals, the method comprising: recording a plurality of electrograms; computing covariance of heart beats; establishing a template matrix upon a comparison of heart beats during a specified time window; classifying pattern using a pattern recognition method; establishing pre-defined threshold; detecting a ventricular tachycardia (VT) when predefined threshold is exceeded; detecting a supraventricular tachycardia (SVT) when predefined threshold is not exceeded.