Method for tachycardia discrimination

Abstract

A cardiac discrimination method in which feature values of a heart related signal (e.g., cardiac biopotentials) determined to be non-baseline are compared with feature values of a heart related signal determined to be normal baseline. The feature values are extracted on an event-basis (a periodically), for obtaining feature values of a complex. For each complex, the feature values form a sequence with the value having the largest absolute value for the sequence given special identity as a fiducial point. The normal baseline complexes' characteristic sequence and a non-baseline complex's sequence are aligned according to the fiducial points, and unoccupied positions on the ends of the sequences resulting from the alignment are filled with zeros to create normal baseline and non-baseline vectors. The similarity value and dissimilarity value of the normalized non-baseline vector with respect to the normalized normal baseline vector are determined. The type of tachycardia (VT or non-VT) and consequently the selection of appropriate therapy are determined by the location in a discrimination plane of a discrimination point, the coordinates of which are equal to the similarity and dissimilarity values. In addition, the location of a similarly generated hemodynamic discrimination point can be used to discriminate hemodynamically stable and unstable tachycardias based on the features derived from events in hemodynamic related signals. Furthermore, physiological indicators may be processed in a similar manner to determine an ideal rate at which the heart should be paced by a pacemaker.