Time relationship between two pacemakers in nodal parasystole

Mechanism of escape, extrasystolic, and parasystolic arrhythmias. Study on an electrical analogue

A simple analogue of the heart consisting of a system of neon relaxation oscillators is presented. The analogue may display rhythm patterns similar to sinus rhythm, escape rhythm, isorrhythmic dissociation with synchronization, atrial extrasystoles, ventricular extrasystoles, and parasystole. The strict rules followed by these arrhythmias, as well as the deviations from the rules commonly followed by the equivalent heart arrhythmias, may be easily reproduced on the analogue. Such features are the Treppe phenomenon and captured beats in escape rhythm, fixed coupling intervals in extrasystoles, partial or complete atrioventricular block in very premature atrial extrasystoles, prolongation of the period following an atrial extrasystole, interpolated premature beats, complete compensatory pause and the rule of bigeminy in ventricular extrasystoles, slight instability of the parasystolic period, multiple length parasystolic periods slightly different from the exact multiples of the parasystolic idioperiod, preference of the parasystoles for certain phase in the sinus cycle, synchronization at a phase difference and fluctuation repeatedly and without interruption from a parasystolic to an extrasystolic rhythm and synchronization in escape rhythm with isorrhythmic dissociation. The mechanisms involved in these phenomena are discussed in detail. The striking similarity between the properties of the cardiac pacemakers and those of the relaxation oscillators on the one hand and betwen the rhythm patterns of the heart and those of the analogue on the other may permit the hypothesis that the mechanisms operating in the analogue may be used in analyzing and understanding heart arrhythmias.