The purpose of this study was to analyze how two different models of "pure" artificial ventricular parasystole (PA) deviated from the rules (numerical description of the number of sinus beats interposed between consecutive manifested PA beats) described in the mathematical model reported by Glass et al. In the latter, two parameters were used so that the ventricular cycle length (TE)/atrial cycle length (TS) ratio was plotted versus the refractory period/TS ratio. Therefore, 30-second rhythm strips were obtained from 6 patients in whom the ventricles were paced while TS was kept constant by atrial stimulation (model 1) and from 7 patients in whom the ventricles were paced during sinus rhythm (model 2). In 45/50 (90%) of pacing runs using model 1 and in 22/25 (88%) using model 2 the expected mathematical rules were observed: a) for any TE/TS ratio there occurred only 3 different values; b) not more than 1 of 3 values was odd; and c) the sum of the lesser 2 values was one integer less than the larger value. In model 1 nonfulfillment of rules occurred because ventricular pacing could not overcome the effects of the initial conditions (given by the moment of the cycle at which the first ventricular stimulus of the run was delivered) but in model 2 this was produced by the normal, autonomically-related variations of sinus cycle lengths. In conclusion, deviations for the mathematical rules were due to deterministic initial conditions (in model 1) and to apparently stochastic fluctuations in sinus rate (in model 2).
|Original language||English (US)|
|Journal||Journal of Investigative Medicine|
|State||Published - Jan 1 1996|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)