Effect of Bipole Configuration on Atrial Electrograms During Atrial Fibrillation JEFFREY M. BAERMAN. KRISTINA M. ROPELLA, ALAN V. SAHAKIAN, JOEL A. KIRSH, and STEVEN SWIRYN From the Division of Cardiology, Department of Medicine, Evanston Hospital, and Northwestern University Medical School, and the Feinberg Cardiovascular Research Institute, and the Departments of Biomedical and Electrical Engineering, Nortbwestern University, Evanston. Illinois BAERMAN, J.M., ET AL.: Effect of Bipole Configuration on Atrial Electrograms During Atrial Fibrilla- tion. Despite an increasing body 0/ work on (he nature of fibrillatory rhythms, and the application of different bipole configurations in anfijibrilialory devices, little published work has assessed (he effect of bipole configuration on the endocardial recordings of fibrillatory rhythms. To address this issue, a spe- cially designed 6 Fr decapolar catheter was used to record in(ra-a(ria/ elec(rograms during sus(ained atriaJ fibrillation in 15 patien(s. SimuKaneous filtered (30-500 Hz) and unfiitered (0.05-5,000 Hz} recordings of atriai fibrillation were performed of four different bipole configurations: (a} 1-mm interelectrode spacing ad/acen( to the atrial wall; (h| 10-mm interelectrode spacing adjacent (0 the atrial wall: (c} 10-mm inter- electrode spacing 24 mm from (he dis(aJ cafhe(er tip; (d) 1-nim intereJectrode spacing 24 mm from the distal catheter tip. One minute of such data was recorded, and each 4.27-second segment (X 14 segments) was analyzed for atrial rate, eJectrogram amp/i(ude, ampJitude probability density function (apdf), me- dian frequency in (he 2-9 Hz band, and eJectrogram morphoJogy. Changes in bipoJe coniiguration resulted in profound changes in caJcuJoted atrial rate, amplitude, and apdfiP < 0.001 by two-way AN OVA in each instance). Specifically, closer interbipole spacing and cJoser proximity to the atriaJ waJJ resulted in Jower calculated atrial rates, higher electrogram amplitudes, and higher apdf values. In contrast, median fre- quency proved to be a more robust measure despite multiple configurations (P> 0.10 by two-way ANOVA). These changes signijicandy afected (he predictive value of previously published detection criteria for rate (P < 0.01) and apdf (P < 0.00001}. Bipole location also affected morphoJogy, with Jocations adjacent to the atrial wall and with closer interbipole spacing having more discrete electrograms and greater apparent organiza(ion (P < 0.0001). Further, when data segments from aJI patients and bipole configurations were grouped, rate and apdf were found to be strongly inversely correlated (r = -0.808}. In concJusion; (1) Bipole con/iguration has important effects on calculated atrial rate, electrogram ampJitude, and apdf during atrial fibrillation; (2) Median frequency and frequency domain analysis may be a more robust way of characterizing atrial fibrillation despite the use of diferent bipole conjigurations; (3) Changes in bfpoJe configuration affect the efficacy of detection criteria, and considerations about (he leveJ of organization of a cardiac rhythm; (4} Rate and apdf may be largely redundant measures of fibrillatory rhythms; and (5) Traditional estimates of atrial rates up to 700/min during atriaJ fibrillation, based on the unipolar or widely spaced bipolar leads of the surface electrocardiogram, reflect the effects of their recording methods, and are an overestimation ofthe true atrial rate. (PACE, Vol. 13, /anuary 1990} antitachycardia devices, atrial rate, jibrillatory electrograms, surface eJectrocardiography Supported in part by the Dee and Moody Institutional Re- search Fund of Evanston Hospital. Address for reprints: leffreyM.Baerman.M.a. Cardiac Elec- . Endocardial catheter systems are receiving trophysiology—Burch 300, Evanston Hospital. 2650 Ridge Av- increasing emphasis in the treatment of fibrilla- enue, Evanston, IL 60201. tory rhythms by antitachycardia devices.'" Pre- 78 January 1990 PACE, Vol. 13