A stochastic characterization of chronic ventricular ectopic activity

A novel approach for studying the generation of ventricular ectopic beats (VEBs) is reported. The approach is based on the hypotheses that VEBs are often generated by a mechanism (VEB mechanism) which is stable over time, but whose activity is modulated by a variety of physiologic influences. The hypothesis suggests that VEB generation should be predictable and should be related to other physiologic parameters. The relationship should be reproducible under similar conditions,. To pursue this hypothesis, an analytic approach was developed which represents VEB generation with a conditional probability distribution. The distribution gives the probability that the next beat is a VEB, given information about the preceding beats. Using this approach on a database of half-hour ECG (electrocardiogram) tapes, it is shown that VEB generation is usually related to the preceding beat type and timing, and that this relationship is often reproducible over time. It is concluded that, in a given patient, VEB generation often shows consistent patterns which might serve as a potentially valuable characterization of the patient´s VEB mechanism.