The link between abnormal intra QRS potentials and premature ventricular beats

Cardiac late potentials have shown the value of high-resolution ECGs for identifying a re-entrant substrate, but they are usually obtained during sinus rhythm and have not been directly linked to an arrhythmia mechanism. Abnormal intra-QRS potentials (AIQPs) are presumed to be a reflection of those late potentials which originate in early activated regions of the ventricles but which do not outlast the QRS complex. Using a high-resolution, digital ambulatory ECG recorder (three channels, 1000 Hz/channel, 16-bit A/D resolution and removable 340- or 510-MByte hard disc), 15 or 22 hours of XYZ lead data were recorded from 80 patients with frequent premature ventricular beats (PVBs). A data structure was centered on PVBs of highly similar morphology. 36 patients met this criterion. Five sinus beats before and after the PVB were organized so that a signal-averaged version of each indexed sinus beat was obtained. A total of 87 PVB sequences were analyzed. Using previously-published methods for obtaining AIQP resulted in 26 sequences with a significant change in the RMS value of the AIQP signal in the sinus beat immediately preceding the PVB. It is hypothesized that the PVB mechanism that is most likely associated with changes in the AIQP is re-entry. For this data set, one could conclude that 30% of the PVBs were caused by re-entry