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Electrophysiologic Characteristics of Atrial TachycardiaOriginating from the Right Pulmonary Veins or PosteriorRight Atrium: Double Potentials Obtained from the Posterior

Wall of the Right Atrium Can Be Useful to Predict Foci of AtrialTachycardia in the Right Pulmonary Veins or Posterior Right Atrium

TAKUMI YAMADA, M.D.,∗ YOSHIMASA MURAKAMI, M.D.,∗ MASAHIRO MUTO, M.D.,∗

TARO OKADA, M.D.,∗ MITSUHIRO OKAMOTO, M.D.,∗ JUNJI TOYAMA, M.D.,∗

YUKIHIKO YOSHIDA, M.D.,† NAOYA TSUBOI, M.D.,† TERUO ITO, M.D.,†TAKAHISA KONDO, M.D.,‡ YASUYA INDEN, M.D.,‡ MAKOTO HIRAI, M.D.,‡

and TOYOAKI MUROHARA, M.D.‡From the ∗Division of Cardiology, Aichi Prefectural Owari Hospital, Cardiovascular Center, Ichinomiya, Japan; †Division of Cardiology,Nagoya Dai-ni Red Cross Hospital, Cardiovascular Center, Nagoya, Japan; and ‡Department of Cardiology, Nagoya University Graduate

School of Medicine, Nagoya, Japan

Double Potentials Can Predict AT Foci. Introduction: The right pulmonary veins (RPVs) and pos-terior wall of the right atrium (PRA) are anatomically located adjacent to each other. The aim of this studywas to demonstrate the electrophysiologic characteristics of atrial tachycardia (AT) originating from thePRA or RPVs.

Methods and Results: A total of 26 consecutive patients with AT originating from the RPVs or PRAunderwent detailed atrial endocardial mapping and successful radiofrequency catheter ablation. Eight fociwere found in the PRA and 18 foci in the RPVs. Analysis of P wave configuration showed that lead V1 wasthe most helpful in distinguishing the AT foci between these two sites. In all cases, double potential (DP)configurations were recorded from several electrodes of a multielectrode catheter placed in the PRA, and thefirst DP component (FP) was the earliest potential recorded from the right atrium during the tachycardia.The amplitude of the FP was higher than that of the second DP component (SP) for AT foci originating inthe PRA, whereas the reverse occurred for those in the RPV. The activation sequence of the FP was fromsuperior to inferior for the AT foci in the superior RPV, whereas the reverse occurred for the AT foci in theinferior RPV.

Conclusion: P wave configuration in lead V1 is helpful in distinguishing AT foci between those originatingin the PRA and RPVs. The DPs obtained from the PRA can be useful in predicting whether AT foci originatefrom the PRA or RPVs. (J Cardiovasc Electrophysiol, Vol. 15, pp. 745-751, July 2004)

radiofrequency catheter ablation, atrial tachycardia, posterior wall of the right atrium, right pulmonary vein,double potential

Introduction

Radiofrequency (RF) catheter ablation has recently provento be effective and safe in eliminating atrial tachycardia(AT).1,2 Many investigations have reported on the major fociof AT, and the major foci have been found not only in theright atrium but also in the left atrium.1,2 The transseptal pro-cedure is needed for RF catheter ablation of AT originatingfrom the left atrium. If it is known ahead of time that the ATis suggested to originate from the right atrium, we can avoidperforming the transseptal puncture for the RF catheter abla-

Address for correspondence: Takumi Yamada, M.D., Division of Cardiology,Aichi Prefectural Owari Hospital, Cardiovascular Center, 2135 Kariyasuka,Yamato-cho, Ichinomiya 491-0934, Japan. Fax: 81-586-45-6800; E-mail:takumi-y@fb4.so-net.ne.jp

Manuscript received 15 September 2003; Accepted for publication14 January 2004.

doi: 10.1046/j.1540-8167.2004.03513.x

tion. However, the electrophysiologic characteristics of ATsoriginating from the right pulmonary veins (RPVs) and pos-terior wall of the right atrium (PRA) are thought to be verysimilar because they are anatomically located contiguouslyto each other. Schwartzman3 reported that double potentials(DPs) reflecting biatrial electrical activation were recordedin the PRA. He warned of the possibility that in the case ofAT originating from the RPV, the DPs might lead to the mis-taken impression of AT originating from the PRA. Soejimaet al.4 demonstrated that the DPs can be helpful in discrimi-nating right atrial from left atrial foci, by comparing the ATsfrom the right superior pulmonary vein (RSPV) with pac-ing from the right atrium to simulate right atrial tachycardia.However, the details of the electrophysiologic characteristicsof ATs originating from the posterior wall near the atrial sep-tum, including those from the right inferior pulmonary vein(RIPV) or PRA, are not yet known. The aim of the presentstudy was to investigate whether the electrophysiologic char-acteristics observed on the surface ECG or intracardiac elec-trograms recorded in the PRA could differentiate whether theAT originates from the RPV or PRA.

746 Journal of Cardiovascular Electrophysiology Vol. 15, No. 7, July 2004

Methods

Patient Characteristics

Twenty-six consecutive patients with AT originating fromthe PRA or RPVs were considered for inclusion in this study(16 men and 10 women; mean age 37 ± 17 years, range16–75). Each patient gave informed consent, and all antiar-rhythmic drugs were discontinued for at least five half-livesprior to the study.

Catheter Positions

In all patients, a 7-French duodecapolar catheter with1-3-1–mm interelectrode spacing (CRISTA CATHTM, CordisWebster, Baldwin Park, CA, USA) was placed in thePRA. A 7-French decapolar catheter with 1-5-1–mminterelectrode spacing between each electrode pair (DaigCorp., Minnetonka, MN, USA) also was inserted into thecoronary sinus (CS) via the subclavian vein. The positionof the proximal electrode pair at the ostium of the CS wasconfirmed with contrast injection. Two 6-French, four-polecatheters with 2-mm interelectrode spacing were placed in thehigh right atrium (HRA) and His-bundle area (HB) for record-ing and stimulation. Intracardiac echocardiography also wasutilized, with a 9-French catheter transducer (Boston Sci-entific, Natick, MA, USA) operating at 9 MHz, positionedin the body of the RA. Catheter placement in the posteriorright atrium medial to the crista terminalis was confirmedby intracardiac echocardiography (Fig. 1). Access to the left

Figure 1. Left: Position of the mapping catheters. Right: Intracardiac echocardiographic recordings from three levels of the contiguity region. The transducer(single arrowhead) is located in the right atrium, at the center of the figure. The double arrowhead indicates the ablation catheter located in the right superiorpulmonary vein. Note that the catheter placed in the posterior right atrium is medial to the crista terminalis. ABL = ablation catheter; CS = coronary sinus;CT = crista terminalis; HRA = high right atrium; ICE = intracardiac echocardiographic catheter; LA = left atrium; LAO = left anterior oblique view;PRA = decapolar catheter placed in the posterior right atrium; RA = right atrium; RAA = right atrial appendage; RAO = right anterior oblique view.

atrium was achieved with an atrial transseptal puncture. Leftatrial mapping was performed via a long sheath (8-French,Daig Corp.) placed into the left atrium through the interatrialseptum. Intravenous heparin was administered to maintain anactivated clotting time >250 seconds after the atrial transsep-tal procedure.

Activation times were measured from where the first rapiddeflection of the local electrogram crossed the baseline.

Electrophysiologic Study

If spontaneous AT did not appear at the beginning of theelectrophysiologic study, AT was provoked by programmedelectrical stimulation from the HRA or CS and/or with con-tinuous infusion of isoproterenol.

Cardiac bipolar electrograms (filtered from 30–400 Hz)were displayed simultaneously with ECG leads II and V1on a multichannel recorder (EPLab Electrophysiology Man-agement System, Quinton Electrophysiology, USA) andrecorded on paper at a speed of 100 to 200 mm/s.

P Wave Analysis

Twelve-lead surface ECG recordings were obtained forall patients. Spontaneous or pharmacologically induced AVblock allowed analysis of the P wave configuration indepen-dent of the T wave. P waves were classified into four types:(1) positive = P waves showing deflections above the iso-electric line; (2) negative = P waves inscribed below the iso-electric line; (3) biphasic = P waves showing both positive

Yamada et al. Double Potentials Can Predict AT Foci 747

and negative components; and (4) isoelectric = flat P waves.Biphasic P waves were recorded as (±) and isoelectric as(0). The P wave configuration in lead V1 during the tachy-cardia was compared with that during sinus rhythm in eachpatient.

Analysis of Intracardiac Electrograms

Activation times were measured from the earliest atrialactivation recorded from the PRA catheter to the onset of thesurface P wave during AT, and the amplitude of the two DPcomponents recorded from the PRA catheter was measured.The local atrial activation time relative to the P wave at thesuccessful ablation site also was measured. In patients withATs originating from the RPVs, the activation sequence ofthe first DP component (FP) recorded from several of theelectrodes placed in the PRA during the AT and differentialpacing, which meant pacing from another RPV to simulateATs from another RPV, was evaluated.

RF Catheter Ablation

The presumed ablation site exhibited the earliest bipolaractivity and/or a local unipolar QS pattern during the AT. RFenergy was applied with an EPT-1000 generator (EP Tech-nologies, Mountain View, CA, USA) delivering a 500-kHzsine wave output between the distal electrode of the ablationcatheter (7-French, EP Technologies) and a cutaneous patchelectrode placed over the left scapula. A temperature controlmodel with a maximal temperature setting of 60◦C was used.If the tachycardia was not affected within 10 seconds, the RFdischarge was terminated, and the catheter was repositionedfor a repeat attempt. If the AT terminated or changed its rate

Figure 2. Schema showing atrial tachycardia sites and representative 12-lead ECGs from patient 21 with a right inferior pulmonary vein focus (left) andpatient 1 with a posterior right atrial focus (right). The open circles in the middle panel indicate the right atrial foci and the closed circles the left atrial foci.The left atrial focus showed positive P waves in lead aVL and positive P waves in lead V1. During sinus rhythm, the P wave was biphasic in lead V1 (�);however, during the tachycardia, lead V1 became completely positive (•), suggesting a left atrial origin. The right atrial focus exhibited positive P waves inlead aVL and biphasic P waves in lead V1 (∗). IVC = inferior vena cava; LAA = left atrial appendage; PV = pulmonary vein; SVC = superior vena cava.Other abbreviations as in Figure 1.

dramatically during the first 10 seconds of the application,the RF delivery was continued for 30 to 60 seconds.

The protocols used to provoke the ATs were repeated toassess the effects of the RF ablation 30 minutes after the lastpulse. Successful ablation was defined as the absence of anyatrial premature beats and the inability to provoke ATs withthe same protocols as those used before the ablation.

Statistical Analysis

Continuous variables are expressed as group mean ± SD.Comparisons of parametric data were analyzed with usingthe Student’s t-test. The Chi-square test was used to comparenonparametric data in different groups. P < 0.05 was consid-ered statistically significant. The sensitivity, specificity, andpositive and negative predictive values were calculated forthe selected ECG leads.

Results

Baseline Data

A total of 26 atrial foci in 26 patients were successfullyablated. Eight foci were found in the PRA (PRA group) and18 foci in the RPVs (RPV group). Twelve of the 18 foci foundin the RPVs were located in the RSPVs and 6 in the RIPVs(Fig. 2). There was no significant difference with regard tomale gender and mean age between the PRA and RPV groups.One patient with a PRA focus and one with an RSPV focushad typical atrial flutter; one with a PRA focus, one withan RSPV focus, and one with an RIPV focus had paroxys-mal atrial fibrillation; and one with an RIPV focus had AVreciprocating tachycardia. Two patients with a PRA focus,

748 Journal of Cardiovascular Electrophysiology Vol. 15, No. 7, July 2004

TABLE 1

P Wave Configuration During Tachycardia

Electrocardiographic LeadPt. TachycardiaNo. Focus I II III aVR aVL aVF V1 sV1

RA Focus1 PRA (+) (+) (−+) (−) (+) (+) (+−) (+−)2 PRA (+) (+) 0 (−) (+) (+) (+−) (+)3 PRA (+) (+) (+) (−) (+) (+) (+−) (+)4 PRA (+) (+) (+) (−) (+) (+) (+−) (+−)5 PRA (+) (+) (−+) (−) 0 (+) (+−) (+−)6 PRA (+) (+) (+) (−) (−) (+) (+) (+)7 PRA (+) (+) (+) (−) 0 (+) (+−) (+−)8 PRA (+) (+) (+) (−) (−) (+) (+) (+−)

LA Focus9 RSPV (+) (+) (+) (−) (+) (+) (+−) (+)10 RSPV (+) (+) (+) (−) (−) (+) (+) (+−)11 RSPV (+) (+) (+) (−) (+) (+) (+−) (+−)12 RSPV (+) (+) (+) (−) (+) (+) (+) (+−)13 RSPV (+) (+) (+) (−) (−) (+) (+) (+)14 RSPV (+) (+) (+) (−) 0 (+) (+) (+−)15 RSPV (+) (+) (+) (−) 0 (+) (+) (+−)16 RSPV (+) (+) (+) (−) 0 (+) (+) (+)17 RSPV (+) (+) (+) (−) (−) (+) (+) (+−)18 RSPV (+) (+) (+) (−) (+) (+) (+) (+)19 RSPV (+) (+) (+) (−) 0 (+) (+) (+−)20 RSPV (+) (+) (+) (−) 0 (+) (+) (+−)21 RIPV (+) (+) (+) (−) (+) (+) (+) (+−)22 RIPV (+) (+) 0 (−) 0 (+) (+) (+−)23 RIPV (+) (+) (+) (−) (+) (+) (+) (+−)24 RIPV (+) (+) 0 (−) (+) (+) (+) (+−)25 RIPV (+) (+) (+) (−) (+) (+) (+) (+−)26 RIPV (+) (+) (+) (−) (+) (+) (+) (+−)

PRA = posterior wall of the right atrium; RIPV = right inferior pulmonaryvein; RSPV = right superior pulmonary vein; sV1 = sinus V1. Otherabbreviations as in Figure 1.

two with an RSPV focus, and one with an RIPV focus hadtachycardia-induced cardiomyopathy.

P Wave Configuration

The P wave configuration for all the patients is summa-rized in Table 1. Leads I, aVR, and aVL did not show asignificant correlation between P wave configuration and lo-cation of the AT foci in either the PRA or RPVs. P wavepolarity in lead I was positive in all cases and in lead aVRwas negative in all cases. Of the 8 cases in the PRA group, 4showed a positive P wave deflection in lead aVL, 2 a negativedeflection, and 2 an isoelectric P wave, whereas in 18 casesin the RPVs group, 9 exhibited a positive P wave deflectionin lead aVL, 3 a negative deflection, and 6 an isoelectric Pwave. Only lead V1 revealed a significant difference in the Pwave polarity between the PRA and RPVs groups (P < 0.01).Of the 8 cases in the PRA group, 6 had a biphasic P wavedeflection in lead V1 and 2 a positive deflection, whereas ofthe 18 cases in the RPVs group, 2 had a biphasic P wavedeflection in lead V1 and 16 a positive deflection.

Sensitivity, Specificity and Predictive Accuracy

Using the criterion that a positive P wave in lead aVL indi-cates AT foci in the PRA resulted in a poor prediction (sensi-tivity 50.0%, specificity 50.0%, positive predictive accuracy30.8%, negative predictive accuracy 69.2%). The criterionthat a positive P wave in lead V1 indicates AT foci in the RPVs

was associated with a sensitivity 88.9%, specificity 75.0%,positive predictive accuracy 88.9%, and negative predictiveaccuracy 75.0%. The combination of a negative P wave inlead aVL or a biphasic P wave in V1 had a sensitivity 100%,specificity 72.2%, positive predictive accuracy 61.5%, andnegative predictive accuracy 100% in predicting AT foci inthe PRA.

Electrophysiologic Study and RF Catheter Ablation

The results of the electrophysiologic study and RF catheterablation are given in Table 2. In all cases, the DP configu-rations were recorded from several of the electrodes placedin the PRA during the tachycardia. The first DP component(FP), second DP component (SP) or HB, and CS electrogramsexhibited the earliest atrial activation during the tachycardiain that order in all cases in the PRA group (Fig. 3A). TheFP, SP and HB, or CS showed the earliest atrial activationduring the tachycardia in that order in all the cases in theRPVs group (Figs. 3B and 3C). The FP was the earliest atrialactivation during the tachycardia in all cases in both groups.The interval between the FP and the onset of the P wave wassignificantly longer in the PRA group than in the RPVs group(−42.6 ± 4.4 ms vs −34.0 ± 3.2 ms; P < 0.001). The am-plitude of the FP was larger than that of the SP in all cases inthe PRA group, whereas the reverse occurred in all cases inthe RPVs group. Both the SP in the PRA group and FP in theRPVs group exhibited a very low amplitude (0.04–0.14 mV).The activation sequence of the FPs was superior to inferiorin all cases of AT originating from the RSPVs, whereas thereverse occurred in all cases with the AT from the RIPVs.With differential pacing from the RPVs, the same result wasobserved.

RF catheter ablation eliminated the ATs in all 26 cases.In all cases in the PRA group, detailed mapping was per-formed with the guidance of a duodecapolar catheter placedin the PRA, and RF applications to an area within 3 mmfrom the guiding catheter eliminated the ATs. The local ac-tivation time relative to the P wave onset at the successfulablation site did not show a significant difference betweenthe two groups (PRA group −47.6 ± 2.8 ms vs RPVs group−48.3 ± 4.4 ms).

TABLE 2

Electrophysiologic Parameters and Results of Radiofrequency Ablation

Tachycardia Focus

PRA (n = 8) RPV (n = 18) P Value

FP-P (ms) −42.6 ± 4.4 −34.0 ± 3.2 <0.001A-P (ms) −47.6 ± 2.8 −48.3 ± 4.4 NS

AmplitudeFP (mV) 0.33 ± 0.12 0.08 ± 0.02 <0.001SP (mV) 0.07 ± 0.02 1.44 ± 0.59 <0.001FP/SP ratio 4.48 ± 1.76 0.06 ± 0.02 <0.001

RP AblationSuccess 8/8 18/18 NSRecurrence 0/8 0/18 NSComplications 0/8 0/18 NSFollow-up period (months) 17 ± 6 15 ± 6 NS

A = local atrial activation at the successful ablation site; FP = firstcomponent of the double potential; RF = radiofrequency; RPV = rightpulmonary vein; SP = second component of the double potential; X-P =activation time of X relative to the P wave. Other abbreviations as in Table 1.

Yamada et al. Double Potentials Can Predict AT Foci 749

In all cases in both groups, no complications occurred, andno recurrence was found during a follow-up period of 15 to17 months.

In two early cases with ATs originating from the RSPVs,some RF applications were delivered to the PRA area because

Figure 3. A: Cardiac recordings during sinus rhythm (left) and those duringthe tachycardia originating from the posterior wall of the right atrium (PRA)(right). Double potentials (DPs) were recorded from several electrodes ofa decapolar catheter placed in the PRA. The single arrowheads indicatethe first DP components (FPs) and the double arrowheads the second DPcomponents (SPs). The amplitude of the FP is spiky and higher than that ofthe SP during both sinus rhythm and the tachycardia. The interval betweenthe double potentials during the tachycardia is longer than that during sinusrhythm. The SPs are low-amplitude potentials and are considered to reflectfar-field left atrial activity. The FP recorded from the fifth pair of electrodesin the PRA is 39 ms before the onset of the P wave. The voltage calibrationon the PRA channels is 1 mV. AT = atrial tachycardia; HBE = His-bundleelectrogram; PRA-1 = distal pair of electrodes in the PRA; PRA-2 to −7 =second to seventh pair of electrodes in the PRA; SR = sinus rhythm. Otherabbreviations are as in Figure 1. B: Cardiac recordings during sinus rhythm(left) and those during the tachycardia originating from the right superiorpulmonary vein (RSPV) (right). The DP configurations recorded during sinusrhythm are similar to those in panel A. However, during the tachycardia, theamplitude of the FP is lower than that of the SP. Note that the order ofoccurrence of the DPs becomes reversed when the tachycardia begins. TheFP from electrode pair PRA-1 is 31 ms before the onset of the P wave. Thesingle arrowheads indicate both the FPs during sinus rhythm and the SPsduring the tachycardia and are considered to reflect right atrial activity.The double arrowheads indicate both the SPs during sinus rhythm and theFPs during the tachycardia and are considered to reflect far-field left atrialactivity. The voltage calibration on the PRA channels is 0.5 mV. CSd(p) =distal (proximal) electrode pair of the CS catheter. C: Cardiac recordingsduring sinus rhythm (left) and those during the tachycardia originating fromthe right inferior pulmonary vein (RIPV) (right). The DP configurationsrecorded during both sinus rhythm and the tachycardia are similar to thosein panel B. Note that the activation sequence of the FP is from superior toinferior for the AT focus in the RSPV, whereas the reverse occurs for the ATfocus in the RIPV. The FP from electrode pair PRA-5 is 30 ms before theonset of the P wave. The voltage calibration on the PRA channels is 0.5 mV.

the DPs recorded in the PRA gave us the mistaken impressionthat the AT was from the PRA. In both cases, there was noeffect on the ATs by any of the RF applications to the PRAarea. However, a common change in the local electrogramsat the ablation site (described later) was observed after the

750 Journal of Cardiovascular Electrophysiology Vol. 15, No. 7, July 2004

Figure 4. Upper panels: Electrograms recorded at the ablation site in thePRA during the tachycardia originating from the right superior pulmonaryvein (A); lower panels: those during sinus rhythm (B). Left panels: Electro-grams recorded before the radiofrequency (RF) applications; right panels:those after the RF applications. The single arrowheads indicate the left atrial(LA) potentials and the double arrowheads the right atrial (RA) potentials.Note that the amplitude of the RA component has been reduced significantlyby the RF applications, whereas that of the LA component has not changed.Other abbreviations are as in Figure 3A.

ablation (Fig. 4). During AT, the amplitude of the FP didnot change and that of the SP became reduced. During sinusrhythm, the amplitude of the SP did not change and that ofthe FP became reduced.

Discussion

P Wave Configuration

Predicting AT foci is very important for the RF catheter ab-lation of AT. Saksena et al.5 performed simultaneous cathetermapping of initiating ATs in right and left atrial regions andconcluded that the P wave morphology on surface ECG didnot correlate with the site of origin in specific atrial regions.Tang et al.6 and Tse et al.7 reported that the P wave configura-tion in leads I, aVL, and V1 was very helpful in discriminatingright atrial from left atrial foci. The present study showed thatthe P wave configuration in lead aVL was not helpful, andonly that in lead V1 was helpful in discriminating whetherthe AT originated from the PRA or from the RPVs. When thecriterion of a positive P wave in lead V1 was used for predict-ing left atrial foci, all of the sensitivity, specificity, positivepredictive accuracy, and negative predictive accuracy resultswere lower in the present study than in the cases reported byTang et al.6 and Tse et al.7 It might be because cases withAT foci from the right atrial septum were not included in theprevious study.6,7 The P wave configuration in lead V1 maynot be a fully reliable index; rather, it may be helpful in dis-criminating right atrial from left atrial foci in the posteriorwall near the atrial septum.

Kuo et al.8 reported that the combination of the P wavepolarity in leads V1 and aVL might be more helpful thanany single lead for predicting whether the arrhythmogenicfocus of atrial fibrillation arises from the superior vena cava

or RSPV. However, that was less helpful than lead V1 indiscriminating whether the AT originated from the PRA orfrom the RPVs in this study. This probably is because moreatrial ectopies from the superior vena cava showed a positiveP wave in lead V1, generally suggesting a left atrial originthan those from the PRA.

Double Potentials

Schwartzman3 reported that the DPs were formed by thesimultaneous recording of biatrial electrical activities, andthe FP or SP reflected either the activity of the right atriumor that of the left atrium, respectively, in the order of theactivation sequence. Soejima et al.4 demonstrated that DPscan be helpful in discriminating right atrial from left atrialfoci. However, their study used pacing models to simulatethe right atrial tachycardia and did not include the ATs origi-nating from the RIPVs. In all cases in the present study, withAT foci from the PRA or RPVs including RIPVs, the DPswere recorded from the PRA. In the ATs originating from thePRA, the FP was suggested to reflect the activity of the PRAdirectly, and the SP reflected the activity of the left atrium as afar-field potential, whereas the DPs in the ATs from the RPVswere suggested to reflect the reverse electrical phenomenon.

Study Limitations

The analysis regarding the sensitivity, specificity, and pre-dictive values of the P wave morphology was performed in alimited population with only AT foci from either the PRA orRPVs in the present study. Therefore, our analysis regardingthe sensitivity, specificity, and predictive values of the P wavemorphology may be less useful in clinical practice where allsites of AT origin have to be considered. However, the analy-sis regarding the sensitivity, specificity, and predictive valuesof the P wave morphology largely depends on the numberof AT foci. Because we wanted to emphasize the efficacy ofthe P wave morphology in discriminating the AT foci in thePRA from those in the left atrium, we analyzed the diagnos-tic ability of the P wave morphology in patients with AT focifrom focal regions.

Clinical Implications

Schwartzman3 did not mention the amplitude of the DPs.However, the characteristics of the DPs in the cardiac trac-ings shown in his report were the same as those of the DPs inthe present study. Although Soejima et al.4 emphasized theusefulness of the reversal of the DPs rather than that of theamplitude of the DPs in discriminating right atrial from leftatrial foci, their data about the amplitude of the ATs from theRSPVs showed the same trend as that in the present study.If they had recorded the DPs using a multipolar catheter,the same results as ours would have been obtained. Thesefindings suggest that left atrial activity is recorded as thelower-amplitude potential of the DPs in the PRA, whereasright atrial activity is recorded as the higher-amplitude po-tential. When DPs preceding the onset of the P wave by morethan 30 ms are recorded from the PRA during ATs, an FPwith a higher amplitude than the SP would indicate an AToriginating from the PRA, and an FP with a lower amplitudethan the SP would indicate an AT originating from the RPV.This rule will be helpful to determine the ablation site for AToriginating from the PRA or RPVs.

Yamada et al. Double Potentials Can Predict AT Foci 751

It has been demonstrated recently that not only atrial pre-mature beats originating from the pulmonary veins9,10 butalso those from the PRA11 can become a trigger of atrial fib-rillation. Although the present study highlighted ATs, the DPsrecorded from the PRA can be a useful index in RF catheterablation of focal atrial fibrillation as well.

Conclusion

The P wave configuration in lead V1 is helpful in distin-guishing AT foci between those originating in the PRA andRPVs. The DPs obtained from the PRA can be useful in pre-dicting whether AT foci originate from the PRA or RPVs.

References

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4. Soejima K, Stevenson WG, Delacretaz E, Brunckhorst CB, Maisel WH,Friedman PL: Identification of left atrial origin of ectopic tachycar-

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9. Haissaguerre M, Jais P, Shah DC, Takahashi A, Hocini M, Quiniou G,Garrigue S, Mouroux AL, Metayer PL, Clementy J: Spontaneous initi-ation of atrial fibrillation by ectopic beats originating in the pulmonaryveins. N Engl J Med 1998;339:659-666.

10. Haissaguerre M, Jais P, Shah DC, Garrigue S, Takahashi A, Lavergne T,Hocini M, Peng JT, Roudaut R, Clementy J: Electrophysiological endpoint for catheter ablation of atrial fibrillation initiated from multiplepulmonary venous foci. Circulation 2000;101:1409-1417.

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