RESUMO
The purpose of this study was to compare the relation of signal averaged variables of the QRS complex to spontaneous and to inducible sustained ventricular tachycardia. Signal averaging of the surface QRS complex was performed in 96 patients with coronary artery disease and ventricular arrhythmias. Twenty eight of them were evaluated by programmed electrical stimulation. Signal average variables were considered abnormal as: 1) the QRS duration as the time from the onset to end point of the QRS vector complex greater than 120 ms, 2) the maximal amplitude of the terminal 40 ms of the QRS vector complex less than 25 microV, 3) the duration of low (less than 40 microV) amplitude signal of QRS vector complex less than or equal to 40 ms. The ventricular late potentials were defined as the pressure of 2 or 3 abnormal averaged variables. Programmed electrical stimulation was performed using single and double extrastimuli at sinus rhythm and at ventricular pacing rates 100, 120, 140 bpm, followed by ventricular burst pacing (3 and 10 consecutive beats) at sinus rhythm. If stimulation of the right ventricular apex did not initiate ventricular arrhythmias (sustained ventricular tachycardia, ventricular fibrillation or two repetitive nonsustained ventricular tachycardias) right ventricular outflow tract stimulation was performed. Sustained ventricular tachycardia was defined as ventricular tachycardia lasting 30 s or requiring termination because hemodynamic compromise. Quantitative comparison of signal averaged variables was performed in patients with inducible versus noninducible ventricular tachycardia and in patients with spontaneous versus non-spontaneous ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)
