title: A shorter R-R interval causes a larger endocardial R wave amplitude in cases with atrial fibrillation.
abstract: Endocardial electrograms were recorded with a Medtronic programmer model (9742A) in 15 patients with implanted pacemakers required for bradycardia and atrial fibrillation. Telemetered unipolar ventricular endocardial electrograms were recorded for 2 minutes, and the R wave amplitudes of the shortest R-R intervals were compared to that of the longest R-R intervals. Eleven of the 15 cases showed R wave amplitudes of the shortest R-R intervals an average of 2.1 mV larger than the R wave amplitudes of the longest R-R intervals. Three cases showed no difference, and one the opposite condition. In all four, the average recorded R-R interval exceeded 670 ms. The shortest R-R interval among the 11 cases with a larger R wave amplitude was 545 +/- 100 ms. The endocardial R wave amplitude of the shortest R-R intervals were larger than the R wave amplitudes of the longest R-R intervals. Shorter intervals were followed by larger endocardial R wave amplitudes (P < 0.005 with the Wilcoxon's rank sum test).
authors.affiliation: Department of Thoracic Surgery, Tokyo Women's Medical College, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yokoyama
authors.forename: S
authors.initials: S
authors.lastname: Nitta
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000628:therapy; D001919:Bradycardia / Q000503:physiopathology* / Q000628:therapy; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D004699:Endocardium / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D013686:Telemetry