The field of nonlinear dynamics offers different approaches to the analysis of electrophysiologic phenomena. Although these approaches have been applied to the evaluation of atrioventricular nodal function, there are no published reports discussing their use in the study of ventricular excitability in the human heart. This communication deals with the findings observed in 4 patients (3 of whom were pacemaker dependent) with complete atrioventricular block while evaluating the ventricular capture capabilities of pacemaker spikes, referred to as stimulusresponse locking (SRL). The approach used by Chialvo and Jalife in their microelectrode studies was followed. Thus the cycle lengths were decreased from 1440 to 300 ms while keeping the voltage (from 7 to 0.5 V) and pulse duration (from 0.5 to 0.25 ms) constant. Although the events occurring between 1:1 and 3:1 were analyzed, we concentrated on those appearing at SRL patterns slightly less, equal to, or greater than 3:1. Multiple patterns were observed (for example, 18:7; 10:4; 8:3; 11:4; 3:1; 14:1) which fulfilled the rule that between M:N and M':N', M+M':N'+N' should be observed. Invariably, the 4:2 pattern reflected jsupernormality. In conclusion, progression of SRL in the human ventricles as a pmction of the pacing cycle length (rate of stimulation) followed a wide variety of patterns observed in other dynamical systems. However, in the human heart, jsupernormality may produce deviations from the expected behavior.
|Original language||English (US)|
|Journal||Journal of Investigative Medicine|
|State||Published - Jan 1 1996|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)