Differentiation between parasystole and reentry in concealed bigeminy.
There are two different theories to explain the mechanism of concealed bigeminy: one is '2:1 concealed reentry'; the other is 'irregular parasystole.' Two exemplary cases of the even-number variant of concealed bigeminy are presented. In case 1, the mechanism can be explained by an irregular parasystole due to a modulated parasystole; however, findings during temporary sinus arrest caused by vagal stimulation indicate that this case is not governed by a parasystole, but by a 2:1 concealed reentry. In case 2, the mechanism can be explained by a 2:1 concealed reentry without parasystole; however, findings during temporary sinus arrest indicate that this case is governed by an irregular parasystole due to a type-I second-degree entrance block. Thus, in cases of concealed bigeminy without pure ectopic cycles, it does not seem easy to explain the mechanism of concealed bigeminy on the theory of a modulated parasystole.
Kinoshita
S
S
Health Administration Center, Hokkaido University, Sapporo, Japan.
Konishi
G
G
Okada
F
F
D000328:Adult; D005117:Cardiac Complexes, Premature / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial; D015716:Electrocardiography, Ambulatory; D006327:Heart Block / Q000503:physiopathology*; D006801:Humans; D008297:Male; D013599:Systole / Q000502:physiology*; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology*; D014630:Vagus Nerve / Q000503:physiopathology