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

Repeated pattern ventricular arrhythmia (RPVA) is often observed in electro cardiogram recordings as a repeated sequence of a fixed number of normal si nus QRS complexes interposed between ventricular ectopic beats. The number of interposed sinus complexes is defined as the order of the repeated patte rn 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 re entry mechanism. Refractory periods of both the normal and reentry conducti on pathways could be estimated from electrocardiogram measured time interva ls. A variable relationship of RR intervals for different orders was found among patients. According to the reentry model, these order changes were mo re likely to occur with changes in the reentry refractory period than with heart rate changes. The longer RR intervals nf interpolated beats in some p atients were also explained by the model.