Method and apparatus for computer enabled analysis of ECG (electro cardiographic) data by exploiting computerized three-dimensional spatial presentation of the measured data using vectors. A three-dimensional presentation of the human heart may be correlated with waveforms specific for standard ECG or derived ECG signals based on the dipole approximation of the heart electrical activity. Additional tools for analyzing ECG data are also provided which may be used to determine the time of cardiac electrical events, to select specific beats for automated cardiac interval determination, and to flag ECGs that have been evaluated by automated means but may benefit by human reading.