On-line processing of orthogonal exercise electrocardiograms

Abstract

A special program has been developed for on-line processing of orthogonal electrocardiograms during exercise with a small computer system. Special measures were taken to obtain high measurement accuracy and to prevent errors due to baseline drift, skeletal muscle noise or premature beats. The program was tested on exercise electrocardiograms from 47 normal men and 50 patients with coronary artery disease. Single representative complexes were obtained by averaging of beats selected with the aid of the spatial velocity time function of the QRS complex and the ST segment. The method used is comparable to, but faster than, cross correlation of the spatial velocity time functions. The onset and end of the QRS complex during exercise were determined using templates derived from the first record of the particular subject. This algorithm resulted in a lower measurement error than other methods for waveform analysis.