Abstract: As particularly useful for implantable medical devices we teach a method and apparatus for orienting electrocardiogram input from electrodes of unknown vector orientation. This can be used for locating a fiducial point in the electrocardiogram signal by which other parameterization of measurements taken of the electrocardiogram signal can be made. It is of particular relevance in any cardio electrogram reading where the orientation of the electrogram signal is unknown, and knowledge of the orientation and a fiducial point can form the basis for useful analysis of electrogram signals for detection of physiologic conditions.