Selective beat signal averaging and spectral analysis of beat intervals to determine the mechanisms of premature ventricular contractions

Selective beat signal averaging and spectral analysis were implemented to identify whether reentry, triggered activity or parasystole is the mechanism of the isolated premature ventricular contraction (PVC). 2-hour, high resolution ECG recordings were digitally obtained from 9 patients with frequent PVCs (>250/hr). For reentry, in 7/9 patients with a positive average for late potentials (LP) there were no changes of LP in sinus beats before and after PVCs. However, changes in the T/U waves in the difference waveform between the pre-PVC beat and its precedent beat (in 2/9 patients), and their T/U wave amplitudes (in 9/9 patients, mean amplitude difference of 0.0269 mV) implied a triggered activity, mechanism. Also, significant periodicities in PVC interval series and low correlation between sinus and PVC intervals (in 9/9 patients), suggested a parasystolic mechanism. Based on the limited data set, triggered activity and parasystole may be significant PVC mechanisms while reentry may not