Comparison of the rectilinear biphasic waveform with the monophasic damped sine waveform for external cardioversion of atrial fibrillation and flutter

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  • Comparison of the Rectilinear BiphasicW

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    Exsintim(RLeffiastuthofibpaprousiwiunsuccess rates for the RLB defibrillator were 99.1% for AFand 99.2% for atrial flutter, and the corresponding suc-

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    Sme(A94da1).deure(BransmstrJ,forsion of AF. Since acquiring the RLB defibrillator earlyafter its release in 1999, we have used it for cardio-veanno

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    thevesetins(C1,056 patients (outpatients and inpatients) who under-went 1,503 external cardioversion procedures for AF

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    2Thersion of AF in a larger sample of patients with AFd atrial flutter. Patients with AF and atrial flutter hadt been evaluated in the previous study.7 We then

    with a RLB defibrillator in our electrophysiologiclaboratory. During this same period, we performed337 cardioversion procedures in 305 patients for atrialflutter using the RLB waveform. Hence, 1,361 pa-tients underwent 1,877 cardioversion procedures withthe RLB defibrillator. The results of all RLB cardio-version procedures were reviewed to determine theoverall efficacy of this waveform in our large clinicalpopulation. We compared the overall success rate ofRLB shocks with that of our previous cardioversionstudy in 2,025 patients (1,490 for AF and 535 for atrialflutter) who underwent 2,848 external cardioversions

    m the Department of Cardiovascular Medicine, Cleveland Clinicndation, Cleveland, Ohio; the Section of Cardiology, University ofbraska Medical Center, Omaha, Nebraska; and Zoll Medical,lington, Massachusetts. Manuscript received November 19,03; revised manuscript received and accepted March 2, 2004.Address for reprints: Mark J. Niebauer, PhD, MD, Department ofrnal Medicine, Section of Cardiology, 982265 Nebraska Medi-Center, Omaha, Nebraska 68198-2265. E-mail: mniebaue@c.edu.ince its introduction in 1962 by Lown et al,1external direct-current cardioversion has been the

    thod of choice2 for terminating atrial fibrillationF) and atrial flutter. This method is safe and 70% to% effective38 when the conventional monophasicmped sine (MDS) shock waveform is used (Figure

    An external defibrillator has been developed thatlivers a rectilinear biphasic (RLB) waveform (Fig-

    1). This defibrillator, manufactured by Zoll Corp.urlington, Massachusetts), was approved based on adomized comparison with the MDS waveform in aall prospective, multicenter trial.1 The trial demon-ated that RLB shocks, using a set energy up to 170are significantly more effective than MDS wave-m shocks of up to 360 J for the external cardiover-004 by Excerpta Medica, Inc. All rights reserved.American Journal of Cardiology Vol. 93 June 15, 2004rospectively compared the RLB results with ourvious MDS waveform cardioversion results to as-s differences in effectiveness in achieving tran-nt, persistent, and overall successful cardioversionsinus rhythm.

    ETHODSThis study was a retrospective trial that evaluatedresults of external transthoracic electrical cardio-

    rsion using the RLB waveform in a general clinicalting. The study was reviewed and approved by thetitutional review board of the Cleveland Clinicleveland, Ohio).From October 1999 to September 2001, there wereaveform With the MSine Waveform

    Cardioversion of Aand Fl

    Mark J. Niebauer, PhD, MD, James E. BPatrick J. T

    ternal cardioversion using the monophasic dampede (MDS) waveform is successful 70% to 94% of thee when using up to 360 J. The rectilinear biphasicB) defibrillator has been shown to be superior incacy to the MDS waveform in atrial cardioversion insmall randomized study. This larger, retrospectivedy compares the results of the RLB waveform withse of the MDS waveform for cardioversion of atrialrillation (AF) and atrial flutter in a large cohort oftients. We performed 1,877 external cardioversioncedures in 1,361 patients for AF and atrial flutter byng the RLB defibrillator. We compared these resultsth those of the MDS defibrillator in 2,025 patients whoderwent 2,818 cardioversion procedures. The overallonophasic Dampedfor Externalrial Fibrillationtterwer, MS, Mina K. Chung, MD, andou, MD

    s rates for the MDS defibrillator were 92.4% and.8% (p 4,000 procedures confirmed and ex-ded those of the previous report by showing a veryh success rate for cardioversion of AF and atrialtter using the RLB waveform. The MDS waveform wasually effective for atrial flutter but significantly lessective in terminating AF. 2004 by Excerpta Med-, Inc.14950002-9149/04/$see front matterdoi:10.1016/j.amjcard.2004.03.006

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    second field reporting the final heart rhythm, and athird field reporting the result after each shock to thepapaareInsucba

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    14200 for AF and 648 for atrial flutter) using an MDSveform defibrillator from August 1996 to Septem-r 1999. The MDS defibrillator delivered up to 360 J,d the RLB defibrillator delivered up to 200 J (inntrast to the device used in the seminal clinicaldy by Mittal et al7 in which a maximum of 170 Js available).Definitions: Overall shock success was defined as

    nversion to a sinus atrioventricular junctionalthm with retrograde P waves or as paced atrialthm immediately after the shock with 1 identifi-

    le atrial depolarization. This confirmed the termina-n of ongoing atrial reentry. If AF was not presenten the patient left the laboratory (usually 15 to 30nutes after the shock), we termed the procedure aersistent success. However, AF or atrial flutter didur in 10% of patients before leaving the labora-y despite additional shocks with transient conver-n from the presenting dysrhythmia in some cases.those cases in which the patient left the laboratoryAF or atrial flutter after an initially successfulck, we termed the procedure a transient success.

    cent publications have addressed the phenomenonAF recurrence after cardioversion. The term im-diate recurrence of AF is now used generally to

    scribe a recurrence that occurs within 1 to 2 minuteser cardioversion, and subacute recurrence de-ibes a recurrence 2 minutes to 2 weeks after suc-sful cardioversion. Unfortunately, much of our dataceded these definitions, and review of the patientcedure records was unclear, in most cases, as tocisely when AF recurred before patient dismissalm our electrophysiologic laboratory. Hence, ournsient success procedures include all immediateurrence and early subacute recurrence procedures.verall success was defined as the sum of the tran-nt and persistent success rates for a given arrhyth-a and waveform, signifying shock effectiveness. Ifwere unable to terminate the arrhythmia to even a

    gle organized atrial beat, the procedure was termedfailure. To confirm whether a procedural result isurately reported, our database records this result in

    different fields: the final procedural result field, a

    URE 1. The current profile of the first phase of the RLB wave-m is relatively flat compared with the higher current peakue seen with the MSD waveform.96 THE AMERICAN JOURNAL OF CARDIOLOGY VOL. 93tient. Any conflicts were resolved by review of thetients chart, where initial and final rhythm strips

    saved, and the written summary of the procedure.the very rare cases in which failure and transientcess could not be resolved by review of the data-

    se or the chart, a failure was reported.Shock waveforms: The RLB waveform was gener-d with an external RLB defibrillator (Zoll Seriesphasic Defibrillator, Zoll Corp.). The waveform wasnerated by a 115-F capacitive discharge, compris-

    an essentially constant-current 6-ms first phased a truncated, exponential 4-ms second phase (Fig-

    1). The amplitude of the phases changed with theected energy, up to a maximum of 200 J. The MDSveform shocks were delivered from a Zoll PD-1200fibrillator, which delivers up to 360 J of energy.Shock electrodes: Adhesive pads for external car-version (Zoll Cardiology Specialty Pad) were useddeliver the RLB and MDS shocks delivered fromcorresponding Zoll defibrillators. These electrode

    tches were positioned in a left or right anteriorentation (depending on the physicians preference)d left posterior chest wall orientation (in all cases).e anterior electrode was circular and had an activeface area of 78 cm2. The posterior electrode wastangular and had an active surface area of 113 cm2.Cardioversion procedure: The standard guidelinesanticoagulation of patients recommended by theerican College of Physicians were adhered to in

    r laboratory.8 Specifically, patients with AF 48urs duration were anticoagulated for 3 weeksfore the cardioversion procedure or underwentnsesophageal echocardiography, where no leftial thrombus was visualized in the presence ofrapeutic anticoagulation with warfarin or intrave-us heparin. Patients were sedated with intravenousium methohexital or etomidate, with constantnitoring of respiration, blood pressure, and trans-

    rmal partial pressure of oxygen. Ventilatory supports provided, if needed, to maintain an adequatertial pressure of oxygen. In all cases, the procedures directed by electrophysiologists at the Clevelandinic, and the initial shock energy, anterior patchsitions, and magnitude of any subsequent shocksried according to the preferences of the staff cardi-gist. There was no specific protocol for selection ofinitial energy setting or for any subsequent energy

    ps or number of shocks before termination of thecedure. At least 1 surface electrocardiographic leads monitored throughout the cardioversion proce-re to determine rhythm before and after shock.hen failure (no discernible P wave) occurred at theximum set energy (200 J for RLB or 360 J forS), then pressure over the anterior patch duringck delivery and/or repositioning of that patch was

    rformed before another attempt. Any concomitantof antiarrhythmic drugs was noted. In rare in-

    nces, intravenous antiarrhythmic drugs were givener initial failure or transient success to produce arsistent success.JUNE 15, 2004

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    age, and proportions of men andwomen were not significantly differ-TABLE 1 Demographics and Clinical Characteristics of Patients in All FourA

    AF

    PA

    M 1WELeHPN CVHDH

    TW

    CP

    A

    drrhythmia and Waveform Groups

    Atrial Flutter

    RLB MDS RLB

    atients (n) 305 535 1,056ge (yrs)All patients 64.5 12.4 65.5 12.3 67.0 12.3Men 64.3 12.0 65.4 12.1 65.5 12.5Women 64.9 13.4 65.9 12.8 70.5 11.0*en 229 (75.1%) 412 (77.0%) 742 (69.8%)omen 76 (24.9%) 123 (23.0%) 321 (30.2%)

    jection fraction 0.44 0.15 0.42 0.15 0.45 0.14ft atrial diameter (mm) 50.4 8.6 47.8 7.9 48.6 9.4eart diseaseatients (n) 275 470 969o structural disease 44 (16.0%) 75 (16.0%) 189 (19.5%)

    oronary artery disease 114 (41.5%) 346 (46.6%) 349 (36.0%)alvular heart disease 100 (36.4%) 283 (36.8%) 321 (33.1%)ypertensive heart disease 31 (11.3%) 60 (12.8%) 174 (18.0%)ilated cardiomyopathy 18 (6.5%) 28 (6.0%) 90 (9.3%)

    48 h 54 (17.5%) 156 (26.4%) 195 (13.5%) 327 days 67 (21.7%) 137 (23.3%) 189 (13.1%) 2

    ARRHYTHMIA AND CONDUCTION DISTURBANCEent between the corresponding AFand atrial flutter groups. However,there was a significant difference inage between men and women withAF (women were 3 years older),but this difference was the same forRLB and MDS groups. This differ-ence was not seen in the atrial fluttergroup.

    We recorded clinical disease infor-mation in 969 patients who underwentcardioversion for AF using the RLBwaveform and 1,359 patients in whomthe MDS waveform was used for thatarrhythmia. We also recorded thesedata in 275 patients with atrial flutterwho were cardioverted with the RLBwaveform and 470 corresponding pa-tients in whom the MDS waveformwas used. Many patients had a combi-nation of2 cardiac diseases. Univar-iate analysis of these data showed thatpatients with AF in the RLB group hadmore structural heart disease (19.5%)than did those in the MDS group byunivariate analysis (15.9%; p 0.05).However, the effect of structural dis-ease on cardioversion outcome wasnot confirmed by multivariate analysisof (p 0.22).

    Arrhythmia duration: The arrhyth-mia duration data are presented inTable 2. Our database recorded ar-rhythmic duration as 3 categories, ifknown:2 days, 2 to 7 days, and7days. We had complete data concern-ing AF duration in 1,441 RLB pro-cedures and 2,014 MDS procedures.Corresponding data were availablefor 308 patients in the RLB groupand 590 patients in the MDS groupwho underwent cardioversion foratrial flutter. Using univariate analy-sis, significantly more MDS cardio-versions were performed for epi-sodes of AF 2 days in duration

    .0%) compared with the RLB group (13.5%; p

    .05). However, multivariate analysis failed to con-arrhythmia duration as a significant factor in

    erall cardioversion success (p 0.08) when cor-ted for other variables. When the arrhythmia dura-n data for atrial flutter were analyzed, the MDSup had significantly more patients with atrial fluttert was 2 days in duration and significantly fewer

    tients with atrial flutter 7 days in duration. Pa-nts with atrial flutter demonstrated the arrhythmiaa longer period before cardioversion than did those

    th AF.Procedural outcome: A persistently successful re-t occurred in 91.9% of RLB cardioversions for AF,

    MDS

    1,490

    67.4 11.666.1 11.870.1 10.6*,027 (68.9%)463 (31.1%)0.44 0.1548.5 9.0

    1,359216 (15.9%)547 (40.2%)487 (38.4%)252 (18.5%)112 (8.2%)33 (2.4%)

    Patients

    up

    MDS

    2,17090 (87.1%)*16 (5.3%)*64 (7.6%)*67 82

    200

    2,01463 (18.0%)*87 (14.2%)64 (67.8%)

    lysis details andStatistical analysis: All continuous variables are ex-ssed as mean SD. Univariate efficacy compari-s across waveforms, arrhythmias, and other non-

    antitative data were performed with the chi-squaret. Unpaired t test was used to compare quantitativeults. Multivariate analysis of clinical characteristicss performed with multivariate linear regression. Forcomparisons, p 0.05 was considered statisticallynificant.

    SULTSClinical characteristics: The clinical characteristicsall patients with AF and atrial flutter are listed inble 1. Mean ejection fraction, left atrial diameter,

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    7 days 183 (59.4%) 297 (50.3%)* 1,057 (73.4%) 1,3

    Univariate analysis results are shown for the arrhythmic duration data. See text for anaiscussion.*p 0.05, MDS versus RLB (same arrhythmic).p 0.01, atrial flutter versus AF (same waveform).ypertrophic cardiomyopathy 7 (2.5%) 8 (1.7%) 28 (2.9%)

    Univariate results for structural disease data are shown.*p 0.05, age for men versus age for women.p 0.05 versus MDS waveform group.Multivariate analysis showed no differences for structural heart disease.

    ABLE 2 Cardioversion Procedure Results and Arrhythmia Duration forith Atrial Fibrillation and Atrial Flutter

    Atrial Flutter Group AF Gro

    RLB MDS RLB

    ardioversion outcomerocedures (n) 337 648 1,540Persistently successful 324 (96.1%) 637 (98.3%) 1,416 (91.9%) 1,8Transiently successful 11 (3.1%) 10 (1.5%) 111 (7.2%) 1Failure 2 (0.8%) 1 (0.2%) 13 (0.9%) 1Mean overall successful

    energy level (J)61 46 231 108 96 50 2

    Median overall successfulenergy level (J)

    50 200 100

    rrhythmic duration (total) 308 590 1,441S/AF CARDIOVERSION USING THE RLB WAVEFORM 1497

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    TABLE 3 Antiarrhythmic Drug Use in the Atrial Fibrillation Groups

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    14d an additional 7.2% of the procedures producednsiently successful cardioversion. Hence, the over-success rate for the RLB waveform was 99.1%

    527 of 1,540). In comparison, MDS waveformcks resulted in persistent success in 87.1% of cor-ponding procedures, and an additional 5.3% werenverted only transiently, resulting in an overall suc-s rate of 92.4% (2,006 of 2,170). The difference

    tween waveform groups was highly significant in allult subgroup comparisons, with fewer failures andre persistently and transiently successful cardiover-ns in the RLB group. This difference was con-ed in the univariate (p 0.001) and multivariate0.0001) analyses.The average persistently successful energy selectedcardioversion of AF using the RLB waveform was 49 J (median 100), and the corresponding valuethe MDS waveform was 264 82 J (median 200).

    r transiently successful cardioversions of AF, theerage energy selected was 127 59 J (median 100)

    the RLB waveform and the corresponding MDSlue was 319 68 J (median 360). We did notrform a statistical analysis to compare the average

    Persistent Success Transien

    MDS RLB MDS

    miodarone 626 (92.3%) 373 (93.5%) 24 (3.5%)*Blocker 493 (90.1%) 538 (93.6%) 24 (4.4%)

    otalol 272 (87.2%) 163 (87.2%) 26 (8.3%)lecainide 189 (88.3%) 147 (92.5%) 12 (5.6%)ropafenone 37 (94.9%) 50 (96.2%) 0 (0%)*rocainamide 104 (88.9%) 34 (89.5%) 10 (8.5%)uinidine 8 (72.7%) 25 (89.3%) 3 (27.3%)oricizine 4 (100%) 11 (73.3%) 0 (0%)isopyramide 10 (90.9%) 26 (78.8%) 1 (9.1%)ofetilide 0 (0%) 75 (83.3%) 0 (0%)*ny AAD 1,541 (86.5%) 1,173 (92%) 92 (5.1%)one 386 (89.4%) 243 (90%) 24 (5.6%)ll patients 1,927 (87.2%) 1,416 (91.7%) 116 (5.2%)

    Combinations of drugs were used in some patients.*p 0.05 versus no-drug group.AAD antiarrhythmic drug.

    ABLE 4 Antiarrhythmic Drug Use in the Atrial Flutter Groups

    MSD

    Persistent Success Transient Success Failure

    miodarone 189 (97.4%) 5 (2.6%) 0 (0%)Blocker 151 (99.3%) 1 (0.7%) 0

    otalol 48 (98%) 0 1 (2%)lecainide 65 (98.5%) 1 (1.5%) 0ropafenone 21 (100%) 0 0rocainamide 64 (100%) 0 0uinidine 7 (100%) 0 0oricizine 2 (100%) 0 0isopyramide 9 (100%) 0 0ofetilide 0 0 0o AAD 167 (97.7%) 3 (1.8%) 1 (0.6%)ll patients 637 (98.3%) 10 (1.5%) 1 (0.2%)

    There were no significant effects of AADs use in patients of either waveform groupatients. See Table 3 for abbreviation.98 THE AMERICAN JOURNAL OF CARDIOLOGY VOL. 93ergy values between the 2 waveforms because theergies were selected in a nonsystematic manner.We previously reported the superior efficacy of

    al simultaneous external shocks using maximumtput of 2 MDS waveform defibrillators in patients inom the maximum 360-J output of a single device

    d failed.9 Because of the unusually high energies ofse cardioversion procedures, those data were notluded in the overall analysis in our MDS group.wever, we performed external cardioversions usingRLB waveform in 14 of those same patients who

    d developed recurrent AF some months after thevious 720-J cardioversions with the MDS wave-m. In all 14 patients, we succeeded in convertingto sinus rhythm using 50- to 200-J RLB shocks.

    The RLB and MDS waveforms were highly suc-sful in cardioversion of atrial flutter, with no sig-cant difference between groups (Table 2). Specif-lly, the persistent success rates for the RLB andS waveforms were 96.1% and 98.3%, respec-

    ely. As expected, the persistent success rate of atrialtter cardioversion was significantly greater (p.001) than that of AF cardioversion regardless of

    ccess Failure Total

    RLB MDS RLB MDS RLB

    21 (5.3%)* 28 (4.1%) 5 (1.2%) 678 39930 (5.2%) 30 (5.5%) 7 (1.2%) 547 57523 (12.3%) 14 (4.5%) 1 (0.5%) 312 18711 (6.9%) 13 (6.1%) 1 (0.6%) 214 1592 (3.8%)* 2 (5.1%) 0 (0%) 39 523 (7.9%) 3 (2.6%) 1 (2.6%) 117 383 (10.7%) 0 (0%) 0 (0%) 11 281 (6.7%) 0 (0%) 3 (20%) 4 153 (9.1%) 0 (0%) 4 (12.1%) 11 33

    13 (14.4%)* 0 (0%) 2 (2.2%) 0 9091 (7.1%) 145 (8.1%) 11 (0.9%) 1,782 1,27526 (9.6%) 22 (5.1%) 1 (0.4%) 432 27017 (7.6%) 167 (7.6%) 12 (0.8%) 2,210 1,545

    RLB Waveform

    al Persistent Success Transient Success Failure Total

    4 103 (98.1%) 2 (1.9%) 0 (0%) 1052 135 (95.7%) 5 (3.5%) 1 (0.7%) 1419 24 (92.3%) 2 (7.7%) 0 266 23 (92%) 2 (8%) 0 251 18 (90%) 2 (10%) 0 204 12 (85.7%) 2 (14.3%) 0 147 1 (100%) 0 0 12 0 0 0 09 3 (100%) 0 0 30 8 (72.7%) 2 (18.2%) 1 (9.1%) 111 58 (98.3%) 1 (1.7%) 0 598 324 (96.1%) 11 (3.3%) 2 (0.6%) 337

    pared with patients without AADs. Combinations of drugs were used in somehathoincHothehapreforAF

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  • waveform. However, a significantly smaller percent-age of atrial flutter cardioversion procedures (1.5% to3.1%) resulted in transient success, compared with theAF patients (5.3% to 7.6%; p 0.001). The percent-age of cardioversion procedural failures was signifi-cantly greater in patients with AF in the MDS groupthan in patients in all other arrhythmic subgroups (p0.001). The use of antiarrhythmic drugs on the over-all cardioversion success rate was not significant bymultivariate analysis (p 0.06) (Tables 3 and 4).

    Adverse events: There were 15 adverse events re-corded during all cardioversion procedures. Therewere no deaths, but 6 patients (5 in the MDS groupand 1 in the RLB group) required hemodynamic sup-port and/or pressors after successful cardioversion dueto bradycardia and hypotension. Six patients (2 in theMDshosupressedpleRLdirthewiinjwerepthesulolo

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    onds after the shock.10 These 2 waveforms are dis-tinct, however, and only the RLB waveform defibril-lator was used in this study. In this study, we reportedthe transient success rates for AF cardioversion withthe 2 waveforms and for atrial flutter, which have notbeen previously reported. We saw no significant de-crease in the proportion of patients with AF who hadtransient success after RLB shocks compared withthose receiving MDS shocks, but we found a signifi-cantly smaller percentage of overt failures with theRLB waveform. Our results showed a significantlylarger proportion of patients with transient successesin addition to persistent successes with the RLB wave-form. However, the relative increase in transientlysuccessful cardioversions in the RLB group can beexplained by the overall reduction in cardioversionfaicesgro

    vitMapre

    1. Larrh2. LatriaJ M3. Hdigi4. L535. Vuneelec1996. VATMcard1567. MMarverssine8.Ant9. SWilsynJ A10.RiccardS group, 2 in the RLB group, and 2 in whom nocks were delivered) required aggressive ventilatoryport (endotracheal intubation or bag mask) due topiratory insufficiency after receiving intravenousation. All 12 of these patients recovered com-tely with supportive treatment. Two patients (in theB group) developed ventricular fibrillation afterect-current shock due to poor synchronization ofshock. These patients were promptly defibrillated

    thout sequelae. One patient reported a rotator cuffury after successful MDS cardioversion. Therere no strokes or transient ischemic cerebral eventsorted within 30 days after cardioversion. However,se data may be incomplete because long-term re-ts are not routinely followed in our electrophysi-gic laboratory database.

    SCUSSIONOur results confirmed and extended our previousults in the smaller, prospective, randomized study,ich demonstrated the superiority of the RLB wave-m over the MDS waveform. Most striking was thenificant decrease in overt failures for cardioversionAF observed with the RLB waveform. The resultsour cardioversion procedures for atrial flutterwed that external electrical cardioversion is highlycessful in this type of arrhythmia, regardless of theveform used.Another, recently approved biphasic waveform de-rillator uses a truncated exponential biphasic wave-m and has also been shown to be superior to theS waveform in conversion from AF for 30 sec-ARRHYTHMIA AND CONDUCTION DISTURBANCElures because the percentage of persistently suc-sful cardioversions also increased in the RLBup.

    Acknowledgment: We thank Dianna Bash, RN, foral assistance in patient data management and Sawnrion-Phillips for expert secretarial assistance inparing this report.

    own B, Amarasingham R, Newman J. New method for terminating cardiacythmias: use of synchronized capacitor discharge. JAMA 1962;182:548555.own B, Perloth MG, Kaidbey S, Abe T, Harken DW. Cardioversion ofl fibrillation: a report on the treatment of 65 episodes in 50 patients. N Engled 1963;269:325331.agemeijer F, Van Houwe E. Titrated energy cardioversion of patients on

    talis. Br Heart J 1975;37:13031307.undstrom T, Ryden L. Chronic atrial fibrillation. Acta Med Scand 1988;223:59.an Gelder IC, Crijns HJ, Van Gilst WH, Verwer R, Lie KI. Prediction of

    ventful cardioversion and maintenance of sinus rhythm from direct currenttrical cardioversion of chronic atrial fibrillation and flutter. Am J Cardiol1;68:4146.an Gelder IC, Crijns HJ, Tielman RG, Brugeman J, de Kam PJ, Gosselink, Verheught FWA, Lie KI. Chronic atrial fibrillation: success of serial

    ioversion therapy and safety of oral anticoagulation. Arch Intern Med 1996;:25852592.

    ittal S, Ayati S, Stein KM, Schwartzmann D, Cavlovich D, Tchou PJ,kowitz SM, Slotwiner DJ, Scheiner MA, Lerman BB. Transthoracic cardio-ion of atrial fibrillation: comparison of rectilinear biphasic versus dampedwave monophasic shocks. Circulation 2000;101:12821287.

    Albers GW, Dalen JE, Laupacis A, Manning W, Petersen P, Singer D.ithrombotic therapy in atrial fibrillation. Chest 2001;119:194S206S.aliba W, Juratli N, Chung MK, Niebauer MJ, Erdogan O, Trohman R,

    koff BL, Augostini R, Mowrey KA, Nadzam GR, Tchou PJ. Higher energychronized external direct current cardioversion for refractory atrial fibrillation.m Coll Cardiol 1999;34:20312034.Page RL, Kerber RE, Russell JK, Trouton T, Wakare J, Gallik D, Olgin JE,

    ard P, Dalzell GW, Reddy R, et al. Biphasic versus monophasic waveform forioversion of atrial fibrillation. J Am Coll Cardiol 2002;39:19561963.S/AF CARDIOVERSION USING THE RLB WAVEFORM 1499

    Comparison of the Rectilinear Biphasic Waveform With the Monophasic Damped Sine Waveform for External Cardioversion of Atrial Fibrillation and FlMETHODSDefinitionsShock waveformsShock electrodesCardioversion procedureStatistical analysis

    RESULTSClinical characteristicsArrhythmia durationProcedural outcomeAdverse events

    DISCUSSIONAcknowledgment

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