[A method of averaged ECG signal does not identify patients with ventricular tachycardia in disorders of intraventricular conduction]. / Technika usredniania sygnalu EKG nie pozwala na wyodrebnienie chorych z czestoskurczem komorowym przy zaburzeniach przewodnictwa sródkomorowego.

ABSTRACT

Conduction defect are known to delay and fragment the ecg signal and may be expected to cause changes on the signal-averaged ecg that mimic ventricular late potentials. The aim of our study was to asses whether signal-averaged ECG (SAE) identify patients (pts) with sustained ventricular tachycardia (VT) after myocardial infarction (MI) who display right or left bundle branch block (RBBB or LBBB). We studied 23 pts with RBBB and 25 pts with LBBB. SEA was recorded with bidirectional filters at 25-250 HZ and 40-250 Hz using Simson method. The total filtered QRS duration (QRSd), root mean square voltage in the terminal 40ms of the QRS (RMS40) and low amplitude signal duration less than 40uV (LAS40)) were measured. Signal-averaged parameters with a filter at 25-250 Hz were [table see text] Signal-averaged parameters with a filter at 40-259 Hz were [table see text] In conclusion SAE parameters do not allow separation of pts with sustained VT from pts with RBBB or LBBB after MI. These data indicate that conduction defects have effects on signal-averaged ecg parameters and may result in masking of ventricular late potentials.