title: Pre-excited RR intervals during atrial fibrillation in the Wolff-Parkinson-White syndrome: influence of the atrioventricular node refractory period.
abstract: The ventricular rate and percent of pre-excited QRS complexes during atrial fibrillation were compared in two groups of patients with the Wolff-Parkinson-White syndrome. Group A consisted of 22 patients whose anterograde effective refractory period of the accessory pathway was longer than that of the atrioventricular (AV) node. Group B consisted of 23 patients in whom this relation was reversed. No patient had organic heart disease. Both groups had a similar effective refractory period of the accessory pathway (288 +/- 37 vs. 280 +/- 26 ms), whereas that of the AV node was shorter in group A than group B (242 +/- 25 vs. 285 +/- 27 ms, p = 0.0001). Patients in group A had a lower percent of pre-excited QRS complexes during atrial fibrillation (39 +/- 43% vs. 93 +/- 20%, p = 0.0001). In the 21 patients whose refractory period was measured, the difference was plotted against the percent of pre-excited QRS complexes; there was a significant correlation between the two (r = -0.83, p less than 0.001). In patients in whom pre-excited RR intervals were present, the pre-excited RR intervals were compared between the two groups. Both groups had similar effective refractory periods of the accessory pathway (265 +/- 22 vs. 280 +/- 27 ms) and ventricle (200 +/- 17 vs. 211 +/- 26 ms). The effective refractory period of the AV node was shorter in group A (248 +/- 22 vs. 285 +/- 28 ms, p = 0.0005). The shortest pre-excited RR interval did not show any difference (244 +/- 37 vs. 265 +/- 41 ms). However, both the average (328 +/- 39 vs. 397 +/- 56 ms, p = 0.001) and longest (495 +/- 109 vs. 666 +/- 205 ms, p = 0.02) pre-excited RR intervals were shorter in group A.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of Kentucky Medical Center, Lexington 40536-0084.
authors.forename: O
authors.initials: O
authors.lastname: Fujimura
authors.forename: C S
authors.initials: CS
authors.lastname: Kuo
authors.forename: B A
authors.initials: BA
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D001281:Atrial Fibrillation / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D001283:Atrioventricular Node / Q000503:physiopathology*; D004594:Electrophysiology; D005260:Female; D006339:Heart Rate; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology*; D012032:Refractory Period, Electrophysiological; D013997:Time Factors; D014927:Wolff-Parkinson-White Syndrome / Q000145:classification / Q000150:complications / Q000503:physiopathology*