The Pattern of the First and Second Return Cycle After Premature Atrial Stimulation

Abstract

Several investigators (Han et al., 1968; Bonke et al., 1969, 1971; Goldreyer and Damato, 1971; Strauss and Bigger, 1972; Klein et al., 1973; Pauley et al., 1973a,b; Strauss et al., 1973; Childers et al., 1973; Miller and Strauss, 1974; Narula, 1974; Ticzon et al., 1975; Masini et al., 1975; Steinbeck and Lüderitz, 1975; Breithardt and Seipel, 1976; Engel et al., 1976; Dhingra et al., 1976; Strauss and Wallace, 1976; Strauss et al., 1976) have studied the effects of premature atrial stimulation on sinoatrial node function. Depending on the prematurity of the atrial stimulation, different types of response were observed. Premature atrial stimulations elicited in the last part of the atrial cycle, induce return cycles (or postextrasystolic cycles) longer than the basal one, making compensatory pauses. When premature atrial stimulations are introduced earlier, return cycles of almost the same length occur (“plateau” effect). In other cases, return cycles shorter than the basal ones may occur when premature atrial stimulations are introduced early in the atrial cycle, shortly after atrial refractoriness is ended.