title: The mechanism of the silent zone on Lorenz plots in atrial fibrillation.
abstract: Lorenz plot is an acknowledged method of the evaluation of sequences of ventricular beats in cardiac arrhythmias, particularly in atrial fibrillation. Lorenz plots are scatterplots that show the R-R intervals as a function of the preceding R-R intervals. The authors of this paper conducted studies of 83 cases of atrial fibrillation; histograms of 500 consecutive R-R intervals were made, determining the mean R-R interval, the functional refraction period (FRP) of AV node and Lorenz plots. In 22 cases (26.5%) the presence of the silent zone on a Lorenz plot was observed, similarly to the study of Nakatsu and al. The silent zone appeared only in cases when the statistical distribution of R-R intervals was reflected by a bimodal histogram (less frequently by a trimodal histogram). The silent zone was never observed in cases of monomodal distribution of R-R intervals. The authors discuss Nakatsu's findings and argue that the silent zone in a Lorenz plot is a morphological expression of bimodal distribution of R-R intervals in atrial fibrillation. The silent zone may be caused by pharmacotherapy (e.g. digoxin), increased parasympathetic tension or other factors prolonging FRP. The presence of the silent zone is not a predictor of a spontaneous termination of atrial fibrillation.
authors.affiliation: Department of Gerontology, Medical Academy of Białystok.
authors.forename: W
authors.initials: W
authors.lastname: Pedich
authors.forename: J
authors.initials: J
authors.lastname: Popiołek
authors.forename: D
authors.initials: D
authors.lastname: Tobiaszewska
mesh_terms: D001281:Atrial Fibrillation / Q000097:blood / Q000175:diagnosis*; D002320:Cardiovascular Physiological Phenomena; D004077:Digoxin / Q000097:blood; D004562:Electrocardiography; D006329:Heart Conduction System / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D016011:Normal Distribution; D012680:Sensitivity and Specificity