title: A study of the factors influencing the appearance of the Ashman phenomenon.
abstract: The electrocardiograms of 29 patients with atrial fibrillation and aberrancy (Ashman phenomenon) were studied. The length of the cycles manifesting aberrancy (R-RA) varied from 270 to 520 msec (mean 372 +/- 55). It correlated negatively with the heart rate (r-0.899, p less than 0.001) and for equal heart rates in separate persons it varied with the length of the preceding R-R cycle (p less than 0.01). Above a critical R-RA length of 520 msec and outside an R-R/R-RA ratio range of 1.5-3.6 aberrancy is never observed: this finding is important for the differentiation of aberrancy from ventricular ectopy.
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis*; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction