Variability in repeated pattern ventricular arrhythmia: application of a reentry model

Repeated pattern ventricular arrhythmia (RPVA) is often observed in electrocardiogram recordings as a repeated sequence of a fixed number of normal sinus QRS complexes interposed between ventricular ectopic beats. The number of interposed sinus complexes is defined as the order of the repeated pattern ventricular arrhythmia. Regions of orders as a function of sinus RR and coupling intervals and duration of refractory periods of normal conduction and reentry pathways were derived from a computer model that simulates a reentry mechanism. Refractory periods of both the normal and reentry conduction pathways could be estimated from electrocardiogram measured time intervals. A variable relationship of RR intervals for different orders was found among patients. According to the reentry model, these order changes were more likely to occur with changes in the reentry refractory period than with heart rate changes. The longer RR intervals of interpolated beats in some patients were also explained by the model.