Objective features of the surface electrocardiogram during ventricular tachyarrhythmias.

The aim of this study was to quantify the electrocardiographic signal characteristics of three types of ventricular arrhythmia; monomorphic ventricular tachycardia, polymorphic ventricular tachycardia and ventricular fibrillation. Patients in a coronary care unit were monitored using a single bipolar ECG lead. Thirty episodes of ventricular tachyarrhythmia (ten from each group) were recorded automatically by computer. Frequency analysis of ten consecutive 1 s epochs from each recording gave 100 spectra for each tachyarrhythmia group. Each spectrum was characterised by the frequency, there were significant differences in all characteristics between the tachyarrhythmia groups (P<0.025). Ventricular fibrillation had a higher mean dominant frequency (4.8 Hz) than polymorphic ventricular tachycardia (3.7 Hz) and monomorphic ventricular tachycardia (3.8 Hz). The dominant frequency of ventricular fibrillation was also more variable than that of monomorphic ventricular tachycardia (P<0.01). Mean peak size was largest for monomorphic ventricular tachycardia (0.78) and smallest for ventricular fibrillation (0.64). The single spectral peaks seen throughout this study indicate that all three tachyarrhythmias have an underlying periodic mechanism. The differences in spectral characteristics show that varying degrees of myocardial electrical organisation can be quantified from surface ECG features.