[Mechanism of parasystole]

Classical parasystoles are described of which the main signs are: variation of the coupling intervals, multiplicity of interectopic intervals, presence of fused ECG complexes. A detailed description of intermittent parasystolia is given. It differs from the classical form by the absence of PS-intervals and fixation of the fused PS-interval with impulses of the main rhythm. The possible mechanisms of fusion of the main and the parasystolic rhythms are described in detail. A detailed table of differential diagnosis of extrasystole and parasystole is given.