ANALYSIS OF ABNORMAL SIGNALS WITHIN THE QRS COMPLEX OF THE HIGH-RESOLUTION ELECTROCARDIOGRAM

This paper presents a new, quantitative approach to measuring abnormal intra-QRS signals, using the high-resolution electrocardiogram (HRECG ), These signals are conventionally known as QRS ''notches and slurs.' ' They are measured qualitatively and form the basis for the ECG ident ification of myocardial infarction, The HRECG is used for detection of ventricular late potentials (LP), which are linked with the presence of a reentry substrate for ventricular tachycardia (VT) after a myocar dial infarction, LP's are defined as signals from areas of delayed con duction which outlast the normal QRS period, Our objective is to quant ify very low-level abnormal signals that may not outlast the normal QR S period, In this work, abnormal intra-QRS potentials (AIQP) were char acterized by removing the predictable, smooth part of the QRS from the original waveform, This was represented as the impulse response of an ARX parametric model, with model order selected empirically from a tr aining data set, AIQP were estimated using the residual of the modelin g procedure, Critical AIQP parameters to separate VT and non-VT subjec ts were obtained using discriminant functions, Results suggest that AI QP indexes are a new predictive index of the HRECG for VT, The concept of abnormal intra-QRS potentials permits the characterization of path ophysiological signals contained wholly within the normal QRS period, but related to arrhythmogenesis, The new method may have other applica tions, such as detection of myocardial ischemia and improved ECG ident ification of the site of myocardial infarction, particularly in the ab sence of Q waves.