Electrophysiological Characteristics and Radiofrequency ...

Circulation Journal Vol.68, December 2004

adiofrequency (RF) ablation is the therapy of choice for patients with the Wolff – Parkinson –White(WPW) syndrome.1–5 It is a curative procedure

with a high success rate and low morbidity.6–10 The identifi-cation of the shortest atrioventricular or ventriculo-atrialconduction time is considered the key to the successfulablation of accessory pathways.6–10 In previous studies, themean ventriculo-atrial (VA) interval at successful ablationsites of concealed accessory pathways (AP) was between33ms and 68ms.6–10 In contrast, AP associated with longretrograde conduction times and decremental conductionproperties are a well known cause of the permanent form ofjunctional reciprocating tachycardia (PJRT), a nearly inces-sant tachyarrhythmia characterized by negative P waves inleads II, III, aVF of the surface electrocardiogram, and anRP/PR ratio >1.11 Several studies have examined the char-acteristics and outcome of RF ablation of these AP.12–14

However, distinctly longer VA conduction times than thetypical values may also be present in a significant subset ofpatients with the WPW syndrome, in the absence of elec-trocardiographic or clinical characteristics of PJRT. Thereis no report of the results of RF ablation in patients with AP

and long VA conduction times who do not have typicalPJRT.

The present study examined the electrophysiologicalcharacteristics and outcomes of RF ablation in 34 patientswho presented with paroxysmal supraventricular tachycar-dia (PSVT) and long VA conduction times.

Patient Population and MethodsAmong 1163 consecutive patients with the WPW syn-

drome who underwent RF ablation of AP at the ChangGang Memorial Hospital between June 1991 and September1999, 34 (2.9%) had VA conduction times of >80 ms (theslow group) in the absence of Mahaim fibers. The VAconduction time was measured during right ventricularpacing at a cycle length of 400ms or during orthodromicatrioventricular (AV) reentrant tachycardia (AVRT). In thepresence of manifest anterograde AP conduction, the AVconduction time was also measured at the site of successfulablation during sinus rhythm. All patients presented withPSVT and an RP/PR ratio <1. No patient suffered fromincessant tachycardia. Eighty consecutive patients with APand VA conduction times <80ms, were chosen as controls(the fast group). All patients in the fast group presentedwith PSVT confirmed to be AVRT during electrophysio-logic study. The electrophysiological characteristics andresults of radiofrequency ablation in the 2 groups werecompared.

Electrophysiologic StudyThe procedures associated with the present study were

reviewed and approved by the Institutional Review Board

Circ J 2004; 68: 1152 –1159

(Received August 2, 2004; revised manuscript received September 8,2004; accepted September 22, 2004)Department of Medicine and Biological Science, Gunma UniversityGraduate School of Medicine, Maebashi, Japan and *Second Sectionof Cardiology, Chang Gung Memorial Hospital, Taipei, TaiwanMailing address: Mamoru Manita, MD, Department of Medicine andBiological Science, Gunma University Graduate School of Medicine,3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan. E-mail:[email protected]

Electrophysiological Characteristics and Radiofrequency Ablation of Accessory Pathways With Slow

Conductive Properties

Mamoru Manita, MD; Yoshiaki Kaneko, MD; Masahiko Kurabayashi, MD; San-Jou Yeh, MD*; Ming-Shien Wen, MD*; Chun-Chieh Wang, MD*;

Fun-Chung Lin, MD*; Delon Wu, MD*

Background Atrioventricular accessory pathways (AP) with unusually long ventriculo-atrial (VA) conductiontimes are present in a significant subset of patients with the Wolff –Parkinson –White (WPW) syndrome, notincluding patients with the permanent form of atrioventricular junctional reciprocating tachycardia.Methods and Results We compared the electrophysiological characteristics and outcomes after radiofrequency(RF) ablation in 34 patients with the WPW syndrome, a VA interval >80ms, and paroxysmal tachycardia with anRP/PR ratio <1 (the slow group), vs 80 patients with WPW syndrome and a VA interval <80ms (the fast group).AP were found in the posteroseptal region significantly more often in the slow than in the fast group. In addition,the decremental conductive properties of the AP were more common in the slow than in the fast group. Catheterablation of AP was highly successful in both groups, although ablation required a greater number of RF applica-tions and longer procedure times in the slow group, especially for AP with decremental conductive properties.Conclusions A posteroseptal AP location was more common in AP associated with long conduction timesthan in AP with typical conductive properties. Both types of AP were successfully ablated, although the slowgroup required longer procedures and more RF energy deliveries. (Circ J 2004; 68: 1152– 1159)

Key Words: Accessory pathway; Atrioventricular reentrant tachycardia; Radiofrequency ablation; Recipro-cating tachycardia; Wolff–Parkinson –White syndrome

R

1153Accessory Pathways With Slow Conduction


of the Chang Gang Memorial Hospital. The electrophysio-logic studies were performed after the patient’s informed,written consent had been obtained and all cardioactivedrugs had been discontinued for at least 3 half-lives. Fourmultipolar electrode catheters were inserted into the femo-ral vein and positioned in the high right atrium, His-bundleregion, coronary sinus (CS), and at the right ventricularapex, for intracardiac recordings and for pacing. Thesurface electrocardiogram (ECG) and intracardiac electro-

grams were displayed simultaneously on a multichanneloscilloscope and printed on a thermal recorder (VR-16,Electronics for Medicine, White Plains, NY, and Midas-2500, PPG Industries, Lexena, KS). Pacing stimuli atapproximately twice the diastolic threshold in strength and2 ms in duration were delivered by a DTU-200 program-mable stimulator (Bloom and Associates, Reading, PA).Detailed studies of AV and VA conduction were carried outon each patient during incremental atrial and ventricular

Fig1. A 12-lead ECG recorded during paroxysmal orthodromic tachycardia. A: 12-lead ECG of patient No. 27. B: 12-lead ECG of patient No. 25.

Fig 2. Right posteroseptal AP with longanterograde conduction time. A: Before abla-tion. A delta wave is present on the surfaceECG, The AV interval duration is 80ms at theearliest ventricular activation site, in theposteroseptal region of the tricuspid annulus,where the tip of the ablation catheter (RFb)was located. B: Immediately after successfulablation. The delta wave has disappearedfrom the surface ECG, and the AV intervalrecorded from the ablation catheter haslengthened to 120ms. The solid vertical linesmark the onset of atrial and ventricular elec-trograms, consecutively. I, aVF; V1, surfaceECG leads; HRA, high right atrium; HBE,His-bundle electrogram; AV =atrioventricularconduction time recorded from the ablationcatheter.

1154 MANITA M et al.


pacing and extrastimulation.A retrograde aortic approach was used to ablate left-

sided AP and an inferior vena cava approach for right-sidedAP. With the ablation catheter positioned near the success-ful ablation site, decremental AP conduction propertieswere considered present if a >30ms rate-dependent prolon-gation of VA or of the atrial-delta wave intervals measuredfrom the electrogram nearest the AP.15 In the case of septalaccessory AP, where retrograde AP conduction could beconfused with retrograde AV node conduction, atrial pre-excitation or prolongation of the VA interval, withoutchange in retrograde activation sequence from prematureventricular stimuli delivered during AVRT when the Hisbundle was refractory, was considered to have occurredover the AP.16

RF AblationThe RF was delivered as continuous, unmodulated,

500kHz sine-wave energy by a model RFG-3C electrosur-gical unit (Radionics, Burlington, MA). The RF pulse wasset at 20 to 30W and delivered for 15 to 30s. The RFenergy was delivered during continuous digital monitoringof the power level and impedance.

A 7 F quadripolar steerable catheter with a 4mm distalbulbous electrode (Mansfield-Webster, Watertown, MA)was introduced percutaneously into a femoral vein, and ad-vanced to the atrial side of the tricuspid valve for ablationof right-sided free wall, anteroseptal, midseptal or rightposteroseptal AP. The catheter was introduced into afemoral artery and advanced to the ventricular or atrialaspect of the mitral annulus for ablation of the left-sidedfree wall or left posteroseptal AP. The accessory pathwaywas localized by mapping the atrial or ventricular activa-tion from uni- and bipolar electrograms recorded by thelarge-tip ablation catheter. When the AP was manifest, theablation site was selected when the following observations

Fig3. Right posteroseptal AP with long retrograde conduction time. A: Before ablation. The earliest atrial electrogramduring orthodromic atrioventricular tachycardia, was recorded from the distal poles of ablation catheter (RFb) in theposterosepal region of the tricuspid annulus, after a retrograde conduction time of 160ms. B: Immediately after RFenergy delivery. Retrograde conduction during ventricular pacing at a cycle length of 500ms has been eliminated, con-firming the successful ablation of the right-sided posteroseptal AP.CS1 to CS4= the distal poles to proximal CS recordings. Other abbreviations are as in Fig2.

Fig4. Lateral AP with long retrograde conduction time. The earliestatrial electrogram during ventricular pacing at a cycle length of400ms was recorded from the ablation catheter (RFb) in the lateralregion of the mitral annulus, after a retrograde conduction time of100ms. RF energy delivered here eliminated the AP.HBEd and HBEp: His-bundle electrogram recorded from the distalpoles and proximal poles of the electrode catheter, respectively. Otherabbreviations are as in Fig2 and 3.



were combined: (1) no R wave was present on the unipolarelectrogram;17 (2) discrete atrial and ventricular electro-grams were present and the onset of the ventricular electro-gram was earlier than the onset of the delta wave;1,3,18–20

and (3) the AV interval was the shortest recorded, andpotentials consistent with AP activation were presentbetween the atrial and ventricular electrograms.1,3,18–20 Inpatients with concealed AP, the ablation site was selectedwhen the following observations were combined:1,3,18–20

(1) the earliest atrial electrogram recorded during ven-tricular pacing or AVRT; (2) the shortest VA interval withpotentials consistent with AP activation during ventricularpacing or AVRT; and (3) discrete atrial and ventricularelectrograms with an appropriate ratio were present.

When the AP was posteroseptal and the shortest intervalbetween the atrial and ventricular electrograms was re-corded near the ostium of the CS, RF energy was firstdelivered to the right posterior septum. However, if theshortest interval between the atrial and ventricular electro-grams was recorded further into the CS, RF was deliveredfirst to the left posterior septum. If ablation of the AP wasunsuccessful in delivery of RF energy to the right or leftposteroseptal area, the contralateral site was targeted.

If the ablation was successful, additional RF energy wasdelivered to the same site. An electrophysiologic study wasperformed after successful ablation and repeated afterisoproterenol infusion, 1 to 4μg/min, to increase of sinusrate by 20% and confirm the success of the procedure.

Statistical AnalysisContinuous variables are expressed as means±SD. Sta-

tistical significance was examined by Student’s t-test forcomparisons between 2 variables. Non-continuous varia-bles were compared by chi-square analysis with the Yatescorrection or Fisher’s exact test. A p value of <0.05 wasconsidered statistically significant.

ResultsRepresentative Electrocardiographic Surface and Intracardiac Recordings

Representative 12-lead ECG recordings of PSVT in 2different patients from the slow group are shown in Fig 1Aand B. Fig 2 shows the intracardiac electrograms in atypical patient from the slow group, who had a long antero-grade AP conduction time. Figs 3 and 4 show intracardiacelectrograms from slow group patients, illustrating the longretrograde AP conduction times. The intracardiac electro-grams of a patient in the slow group who had retrogradedecremental conduction properties of the AP are illustratedin Fig5.

Study Group CharacteristicsThe slow group included 18 men and 16 women (mean

age =43±15 years, range 8–66), 8 with manifest and 26with concealed AP (Table 1). The mean AV conductiontime was 93±25 ms (range 80–153), and the mean VA con-duction time was 108±30ms (range 80–180ms). The fastgroup included 45 men and 35 women (mean age =36±18years, range 7–77) with AP and VA conduction times <80ms, including 40 patients with manifest and 40 with con-cealed AP. The AV conduction time was 39±11ms (range28–72), and the VA conduction time was 56±33ms (range50–76).

Location of Accessory PathwaysThe distributions of AP locations were significantly

different between the 2 groups (Table 2). Over 50% of APin the slow group were in the posteroseptal region, includ-ing 11 AP (32.4%) in the right posteroseptal and 8 (23.5%)in the left posteroseptal regions. In contrast, in the fastgroup, only 6 AP (7.5%) were in the right posteroseptal and10 (12.5%) in the left posteroseptal regions (p=0.001 vs the

Fig5. Right posteroseptal AP with retrograde decremental conduction properties demonstrated by single ventricularextrastimulation (S1-S2=270ms) during ventricular pacing at an S1-S1 cycle length=500ms.The interval from the stimulation artifact to the earliest atrial electrogram recorded at the proximal CS (CSp) lengthensfrom 90ms during S1-S1 pacing to 195ms after S2 extrastimulation, consistent with decremental retrograde conductionthrough the AP. During orthodromic AV reentrant tachycardia induced by S2, the shortest VA interval measured at CSpwas 155ms. CSd= the distal poles of the CS recordings. Other abbreviations are as in Fig2 and 4.



slow Group). However, in the slow group there was norelationship between distribution of AP location and pres-ence vs absence of decremental properties.

Electrophysiologic ObservationsOrthodromic AV reentrant tachycardia was induced in

all patients in both study groups. The mean tachycardiacycle length and His-atrial (HA) interval during tachy-cardia were both longer in the slow group than in the fastgroup, suggesting that the longer tachycardia cycle lengthwas determined by the slower conduction across the AP(Table3). The atrio-His (AH) interval during tachycardia,and the anterograde or retrograde effective refractoryperiods of the AP were similar in both groups.

Retrograde decremental conduction properties of the APwere observed more frequently in the slow group than inthe fast group, although only approximately one third ofpatients in the slow group had retrograde decrementalproperties, including 2 patients with manifest and 10 withconcealed AP (Table3). In the 2 patients with manifest APand retrograde decremental properties, no anterogradedecremental conductive properties were observed.

Radiofrequency AblationThe AP was successfully ablated in all patients in both

groups. In no patient was RF energy delivered to the mid-dle cardiac vein or other branches of the CS to eliminateAP conduction. All procedures were uncomplicated. Im-

Patient no. Age/sexDelta AP AV VA

DPa DPrTCL AH HA ERPa ERPr

wave location (ms) (ms) (ms) (ms) (ms) (ms) (ms)

1 59/M + RPS 93 120 – + 420 260 160 430 400 2 59/F + RPS 80 120 – + 380 200 180 300 230 3 60/M + RPS 100 125 – – 290 110 180 290 280 4 51/M + RPS 80 165 – – 420 190 230 290 280 5 65/M + RPS 80 100 – – 320 160 160 260 230 6 55/F + LPS 80 140 – – 350 150 200 340 340 7 27/M + RP 153 145 – – 340 140 200 270 280 8 42/M + LPL 80 105 – – 390 140 250 270 250 9 8/F – LAL ND 113 ND + 300 120 180 ND 21010 38/M – LL ND 110 ND + 380 110 270 ND 34011 52/F – LL ND 80 ND + 320 130 190 ND 24012 71/M – LP ND 80 ND + 470 320 150 ND 33013 18/M – LPL ND 100 ND + 350 180 170 ND 22014 70/F – LPL ND 103 ND + 380 130 250 ND 28015 47/F – LPS ND 100 ND + 340 180 160 ND 25516 65/F – RPS ND 160 ND + 410 200 210 ND 26017 60/M – RPS ND 180 ND + 420 180 240 ND 31018 43/M – RPS ND 170 ND + 310 120 190 ND 23019 27/F – LL ND 94 ND – 330 120 210 ND 36020 38/F – LL ND 100 ND – 290 90 200 ND 37021 47/F – LPS ND 80 ND – 310 130 180 ND 23022 32/F – LPS ND 87 ND – 430 270 160 ND 30023 71/M – LPS ND 93 ND – 350 170 180 ND 31024 48/M – LPS ND 95 ND – 360 185 175 ND 32025 62/M – LPS ND 86 ND – 290 120 170 ND 28026 77/M – RPL ND 126 ND – 400 150 250 ND 25027 56/F – RPS ND 80 ND – 350 185 165 ND 26028 41/M – RPS ND 80 ND – 280 240 140 ND 27029 35/F – LL ND 127 ND – 320 110 210 ND 20030 13/M – LL ND 140 ND – 270 90 180 ND 39031 44/F – LL ND 165 ND – 290 80 210 ND 26032 54/F – LL ND 100 ND – 440 220 220 ND 40033 49/F – RPS ND 120 ND – 430 240 190 ND 27034 51/F – LPS ND 82 ND – 390 240 150 ND 280

Table 1 Characteristics of Patients With AP Associated With Long Conduction Time

AH, atrio-His interval during tachycardia; AV, atrioventricular interval measured at successful ablation site; DPa, anterograde decremental properties; DPr, retrograde decremental properties; ERPa, anterograde effective refractory period of AP; ERPr, retro-grade effective refractory period of AP; LAL, left anterolateral; LL, left lateral; LP, left posterior; LPL, left postero lateral; LPS, left postero septal; ND, not determined; TCL, tachycardia cycle length; RP, right posterior; RPL, right posterolateral; RPS, right posteroseptal; VA, ventriculo-atrial interval.

Table 2 Location of Atrioventricular Accessory Pathways in Both Study Groups

AP locationFast group Slow group Slow group

(n=80) (n=34) DP (n=12) No DP (n=22)

RFW 22 (27.5%) 2 (5.9%) 0 (0.0%) 2 (9.1%)PS 16 (20.0%) 19 (55.9%) 6 (50.0%) 13 (59.1%)

LFW 42 (52.5%) 13 (38.2%) 6 (50.0%) 7 (31.8%)p=0.001 p=0.39

DP, decremental properties; LFW, left free wall; PS, posterior septum; RFW, right free wall.



portant procedural characteristics in each study group arepresented in Table4. A probable AP potential was recordedat the successful ablation site with similar frequency inboth groups (shown in Table 4). Likewise, the A/V ratio atthe site of successful ablation was similar in both groups. Agreater number of RF energy deliveries were needed in theslow group than in the fast group to achieve permanent APconduction block. In addition, the overall procedure timewas significantly longer in the slow group than in the fastgroup. In the slow group, a greater number of RF energydeliveries were needed to eliminate AP with than AP with-out decremental properties, and the overall procedural timewas significantly longer in patients whose AP exhibiteddecremental conduction.

DiscussionThe main findings of our study are: (1) AP associated

with long conduction time were more commonly located inthe posteroseptal region than AP with more typical conduc-tive properties; (2) the decremental conductive propertiesof the AP were observed more frequently in patients withlong AP conduction times than in patients with moretypical AP conduction times, though, in most cases, an APassociated with a long conduction time did not exhibitdecremental conductive properties; and (3) a high successof catheter ablation was obtained with both types of AP,although the number of RF deliveries was higher andoverall procedure time longer in the slow group, especiallywhen the AP exhibited decremental conductive properties.

Location and Electrophysiologic Characteristics of AP Associated With Long Conduction Times

In the present study, AP associated with long retrogradeconduction times were frequently located in the postero-septal region. This strongly suggests that these patients are different from typical patients with the WPW syn-drome. In addition, antegrade AV conduction time was

longer in the slow group than in the fast group. Xie B et aland Haissaguerre et al found the AV conduction time atsuccessful AP ablation sites to be longest in the postero-septal area and shortest in the right anterior region.21,22 Theposteroseptal region, located at the crux of the heart, wherethe 4 cardiac chambers meet posteriorly, is anatomicallycomplex.23 Anatomical variations may play a role in pro-longing the conduction time of AP. However, in the presentstudy and several previous studies, the location of slowlyconducting AP was not systematically posteroseptal, butcould be found anywhere along the tricuspid,14 or mitralvalve annuli.13,14,24 The most likely explanation for theprolonged conduction time is slow and anisotropic conduc-tion across a tortuous AP and through its connections to theatrial and ventricular myocardium.25 Some AP associatedwith long conduction times also exhibited decrementalproperties in the present study. The presence of decremen-tal properties over AP remains unexplained, though severalputative mechanisms have been proposed. In the presentstudy and in several earlier studies, posteroseptal APlocated near the AV node had the highest prevalence ofdecremental conduction, raising the possibility that the APis an AV node-like structure.16,26,27 Decremental conductionin one direction, but not in the other, may also be due to APgeometry or fiber orientation. Pathologic examinations ofseptal AP in patients with PJRT showed tortuous courseswith changes in axial resistance, further supporting thecontribution of AP geometry to the decremental conductiveproperties.28 Finally, a role played by impedance mismatchbetween the AP and the atrium or ventricle has also beensuggested.29,30

Difference Between Our Population and Patients With PJRT

The reentrant circuit in PJRT is characterized by antero-grade conduction through the AV node and retrogradeconduction over an AP capable of slow retrograde conduc-tion only, with decremental properties. Although both

Table 3 Electrophysiologic Observations in Both Study Groups

Fast group Slow groupp

Slow groupp

(n=80) (n=34) DP (n=12) No DP (n=22)

DP 6 (7.5%) 12 (35.5%) 0.0002TCL (ms) 326±56 356±54 0.008 373±51 347±54 0.18AH (ms) 161±56 166±58 0.67 178±63 160±55 0.42HA (ms) 164±27 193±33 <0.0001 196±39 191±30 0.71ERPa (ms) 285±55 306±56 0.33 365±92 287±29 0.08ERPr (ms) 264±59 286±55 0.07 275±58 291±53 0.42

AH, atrio-His interval during tachycardia; DP, decremental properties; ERPa, anterograde effective refractory period of AP; ERPr, retrograde effective refractory period of AP; HA, His-atrio interval during tachycardia; TCL, tachycardia cycle length.

Table 4 Comparison of Radiofrequency Ablation Procedural Characteristics in Each Study Group

Fast group Slow groupp

Slow groupp

(n=80) (n=34) DP (n=12) No DP (n=22)

AP potential 24 (30.0%) 8 (23.5%) 0.63 2 (16.7%) 6 (27.3%) 0.78 A/V ratio 0.33±0.34 0.37±0.67 0.67 0.22±0.17 0.45±0.82 0.35 RF energy (W) 28.4±6.3 27.0±3.3 0.24 27.3±4.2 26.9±2.8 0.75 Time to AP ablation (s) 3.1±1.7 4.8±3.6 0.002 4.4±2.9 5.0±3.9 0.69 Overall procedure time (min) 21.6±21.1 37.0±36.1 0.006 54.9±47.7 27.2±24.0 0.03 No. of RF deliveries 3.3±3.2 7.6±10.4 0.001 14.2±14.9 4.0±4.0 0.005

A/V, the ratio of atrial potential/ventricular potential amplitudes at the site of successful ablation; time to AP ablation, time from onset of RF delivery to AP conduction block.



incessant and paroxysmal types of tachycardia have beendescribed, PJRT is predominantly incessant or present for>10% of the day.12,31,32 The atrial insertion of the AP isoften near the ostium of the CS, although it may also befound in the right or left posteroseptal regions, the mid-septal space, or even the free walls.12–14 The anatomicalsubstrate was described by Critelli et al as fascicle with amarkedly tortuous course, which may explain the slow anddecremental conduction observed during electrophysiologi-cal studies.33

The clinical, electrocardiographic, and electrophysio-logic observations made in the present study are differentfrom typical PJRT in several respects. First, the tachycar-dias were paroxysmal, not incessant, in all patients.Second, a long RP interval was not systematically presentin a 12-lead ECG in all patients, as illustrated in Fig 1A.Third, the tachycardia cycle length and retrograde APconduction time were distinctly shorter in our populationthan has been previously described with PJRT.12–14,33,34

Fourth, decremental properties of the AP were demonstra-ble in only a relatively small subset of our patients. Thus,we believe that the tachycardia observed in the presentstudy was distinctly different from the tachycardia classi-cally described in patients with PJRT, and that it should beclassified separately.

Radiofrequency Ablation for AP Associated With a Long Conduction Time

The permanent elimination of AP associated with slowretrograde conduction required a greater number of RFenergy applications, longer time from onset of RF deliveryto block of AP conduction, and longer procedure time thanin patients with the usual form of WPW syndrome. In addi-tion, AP with decremental conductive properties required agreater number of RF energy applications and a longermean procedure time AP without decremental properties.

Wen et al found that posteroseptal AP can be success-fully ablated from either the transvenous atrial or the retro-grade transaortic approach, and that delivery of energy tothe CS or middle cardiac vein is unnecessary in mostpatients.35 However, in some studies, RF ablation forposteroseptal AP, common in our population, has beenmore difficult than for AP in other areas.19,20 Failure toidentify a posteroseptal AP as being left-sided, as opposedto right-sided, may also be a cause of prolonged attempts atcatheter ablation.36 Apart from the complex anatomicalstructures involved, difficulties in the anticipation of theaccurate right vs left side of the posterior septum before theprocedures, may have been an important cause of lengthyablation attempts in our population. Several algorithmsdeveloped to distinguish left from right posterior paraseptalaccessory pathways may be useful in locating posteroseptalAP associated with long conduction times and facilitatetheir ablation.37,38

Another important reason for the delayed success of ourablation attempts is that criteria of successful outcomespreviously described for concealed AP, such as visualimpression of continuous electrical activity between ven-tricular and atrial electrograms,2 or pseudo-disappearanceof the atrial electrogram during retrograde conduction overthe AP,39 were not applicable in our population because ofthe slow AP conduction. Therefore, we spent more timelocalizing the earliest atrial electrogram or the shortest VAinterval during retrograde conduction over the AP, espe-cially those with decremental properties.

ConclusionsThe present study demonstrates that AP associated with

long conduction times were significantly more likely to bein a posteroseptal AP location than AP associated withtypical conductive properties. Decremental conduction wasobserved more often in AP with slow retrograde conduc-tion than in AP with typical retrograde conduction. Theablation success rate was very high in both types of AP,although the precise localization of the AP in the slowgroup was more time-consuming than in the fast group.

Reference1. Jackman WM, Wang XZ, Friday KJ, Roman CA, Moulton KP,

Backman KJ, et al. Catheter ablation of accessory atrioventricularpathways (Wolff – Parkinson –White syndrome) by radiofrequencycurrent. N Engl J Med 1991; 324: 1605–1611.

2. Calkins H, Kim YN, Schmaltz S, Sousa J, el-Atassi R, Leon A, et al.Electrogram criteria for identification of appropriate target sites forradiofrequency catheter ablation of accessory atrioventricular con-nections. Circulation 1992; 85: 565–573.

3. Calkins H, Sousa J, el-Atassi R, Rosenheck S, de Buitleir M, KouWH, et al. Diagnosis and cure of the Wolff–Parkinson–White syn-drome or paroxysmal supraventricular tachycardias during a singleelectrophysiologic test. N Engl J Med 1991; 324: 1612–1618.

4. Kuck KH, Schluter M, Geiger M, Siebels J, Duckeck W. Radiofre-quency current catheter ablation of accessory atrioventricular path-ways. Lancet 1991; 337: 1557–1561.

5. Grant AO. Recent advances in the treatment of arrhythmias. Circ J2003; 67: 651–655.

6. Bashir Y, Heald SC, Katritsis D, Hammouda M, Camm AJ, WardDE. Radiofrequency ablation of accessory atrioventricular pathways:Predictive value of local electrogram characteristics for the identifi-cation of successful target sites. Br Heart J 1993; 69: 315–321.

7. Chen X, Borggrefe M, Shenasa M, Haverkamp W, Hindricks G,Breithardt G. Characteristics of local electrogram predicting success-ful transcatheter radiofrequency ablation of left-sided accessorypathways. J Am Coll Cardiol 1992; 20: 656–665.

8. Grimm W, Miller J, Josephson ME. Successful and unsuccessfulsites of radiofrequency catheter ablation of accessory atrioventricularconnections. Am Heart J 1994; 128: 77–87.

9. Lin JL, Schie JT, Tseng CD, Chen WJ, Cheng TF, Tsou SS, et al.Value of local electrogram characteristics predicting successfulcatheter ablation of left-versus right-sided accessory atrioventricularpathways by radiofrequency current. Cardiology 1995; 86: 135 –142.

10. Silka MJ, Kron J, Halperin BD, Griffith K, Crandall B, Oliver RP, etal. Analysis of local electrogram characteristics correlated with suc-cessful radiofrequency catheter ablation of accessory atrioventricularpathways. Pacing Clin Electrophysiol 1992; 15: 1000–1007.

11. Coumel P, Cabrol C, Fabiato A, Gourgon R, Slama R. Tachycardiepermanente par rythme reciproque. Arch Mal Coeur Vaiss 1967; 60:1830–1864.

12. Gaita F, Haissaguerre M, Giustetto C, Fischer B, Riccardi R,Richiardi E, et al. Catheter ablation of permanent junctional recipro-cating tachycardia with radiofrequency current. J Am Coll Cardiol1995; 25: 648–654.

13. Okumura K, Henthorn RW, Epstein AE, Plumb VJ, Waldo AL. “In-cessant” atrioventricular (AV) reciprocating tachycardia utilizing leftlateral AV bypass pathway with a long retrograde conduction time.Pacing Clin Electrophysiol 1986; 9: 332–342.

14. Ticho BS, Saul JP, Hulse JE, De W, Lulu J, Walsh EP. Variablelocation of accessory pathways associated with the permanent formof junctional reciprocating tachycardia and confirmation with radio-frequency ablation. Am J Cardiol 1992; 70: 1559–1564.

15. Murdock CJ, Leitch JW, Teo WS, Sharma AD, Yee R, Klein GJ.Characteristics of accessory pathways exhibiting decremental con-duction. Am J Cardiol 1991; 67: 506–510.

16. Chen SA, Tai CT, Chiang CE, Lee SH, Wen ZC, Chiou CW, et al.Electrophysiologic characteristics, electropharmacologic responsesand radiofrequency ablation in patients with decremental accessorypathway. J Am Coll Cardiol 1996; 28: 732–737.

17. Haissaguerre M, Dartigues JF, Warin JF, Le Metayer P, MontserratP, Salamon R. Electrogram patterns predictive of successful catheterablation of accessory pathways: Value of unipolar recording mode.Circulation 1991; 84: 188–202.



18. Calkins H, Langberg J, Sousa J, el-Atassi R, Leon A, Kou W, et al.Radiofrequency catheter ablation of accessory atrioventricular con-nections in 250 patients: Abbreviated therapeutic approach to Wolff –Parkinson – White syndrome. Circulation 1992; 85: 1337–1346.

19. Lesh MD, Van Hare GF, Schamp DJ, Chien W, Lee MA, Griffin JC,et al. Curative percutaneous catheter ablation using radiofrequencyenergy for accessory pathways in all locations: Results in 100 con-secutive patients. J Am Coll Cardiol 1992; 19: 1303–1309.

20. Schluter M, Geiger M, Siebels J, Duckeck W, Kuck KH. Catheterablation using radiofrequency current to cure symptomatic patientswith tachyarrhythmias related to an accessory atrioventricular path-way. Circulation 1991; 84: 1644–1661.

21. Xie B, Heald SC, Camm AJ, Rowland E, Ward DE. Characteristicsof bipolar electrograms during anterograde mapping: The importanceof accessory atrioventricular pathway location. Am Heart J 1996;131: 720–723.

22. Haissaguerre M, Fischer B, Warin JF, Dartigues JF, Lemetayer P,Egloff P. Electrogram patterns predictive of successful radiofre-quency catheter ablation of accessory pathways. Pacing Clin Elec-trophysiol 1992; 15: 2138–2145.

23. Cox JL. Anatomy of the “posterior septal space”. Am J Cardiol 1991;68: 675–677.

24. Chen IC, Yeh SJ, Wen MS, Lin FC, Wu D. Radiofrequency ablationtherapy in concealed left free wall accessory pathway with decre-mental conduction. Chest 1995; 107: 41–45.

25. Spach MS, Miller WT 3rd, Geselowitz DB, Barr RC, Kootsey JM,Johnson EA. The discontinuous nature of propagation in normalcanine cardiac muscle: Evidence for recurrent discontinuities ofintracellular resistance that affect the membrane currents. Circ Res1981; 48: 39–54.

26. Denes P, Kehoe R, Rosen KM. Multiple reentrant tachycardias dueto retrograde conduction of dual atrioventricular bundles with atrio-ventricular nodal-like properties. Am J Cardiol 1979; 44: 162–170.

27. Klein GJ, Prystowsky EN, Pritchett EL, Davis D, Gallagher JJ.Atypical patterns of retrograde conduction over accessory atrio-ventricular pathways in the Wolff – Parkinson – White syndrome.Circulation 1979; 60: 1477–1486.

28. Critelli G, Gallagher JJ, Monda V, Coltorti F, Scherillo M, Rossi L.Anatomic and electrophysiologic substrate of the permanent form ofjunctional reciprocating tachycardia. J Am Coll Cardiol 1984; 4:601–610.

29. Inoue H, Zipes DP. Conduction over an isthmus of atrial myocar-dium in vivo: A possible model of Wolff–Parkinson–White syn-drome. Circulation 1987; 76: 637–647.

30. De la Fuente D, Sasyniuk B, Moe GK. Conduction through a narrowisthmus in isolated canine atrial tissue: A model of the W–P–Wsyndrome. Circulation 1971; 44: 803–809.

31. Guarnieri T, Sealy WC, Kasell JH, German LD, Gallagher JJ. Thenonpharmacologic management of the permanent form of junctionalreciprocating tachycardia. Circulation 1984; 69: 269–277.

32. Yagi T, Ito M, Odakura H, Namekawa A, Otomo J, Ishida A. Elec-trophysiologic comparison between incessant and paroxysmal tachy-cardia in patients with permanent form of junctional reciprocatingtachycardia. Am J Cardiol 1996; 78: 697–700.

33. Critelli G, Gallagher JJ, Perticone F, Monda V, Scherillo M,Condorelli M. Transvenous catheter ablation of the accessory atrio-ventricular pathway in the permanent form of junctional reciprocat-ing tachycardia. Am J Cardiol 1985; 55: 1639–1641.

34. O’Neill BJ, Klein GJ, Guiraudon GM, Yee R, Fujimura O, BoaheneA, et al. Results of operative therapy in the permanent form of junc-tional reciprocating tachycardia. Am J Cardiol 1989; 63: 1074 –1079.

35. Wen MS, Yeh SJ, Wang CC, King A, Lin FC, Wu D. Radiofre-quency ablation therapy of the posteroseptal accessory pathway. AmHeart J 1996; 132: 612–620.

36. Morady F, Strickberger A, Man KC, Daoud E, Niebauer M, Goyal R,et al. Reasons for prolonged or failed attempts at radiofrequencycatheter ablation of accessory pathways. J Am Coll Cardiol 1996;27: 683–689.

37. Chiang CE, Chen SA, Tai CT, Wu TJ, Lee SH, Cheng CC, et al.Prediction of successful ablation site of concealed posteroseptalaccessory pathways by a novel algorithm using baseline electro-physiological parameters: Implication for an abbreviated ablationprocedure. Circulation 1996; 93: 982–991.

38. Takenaka S, Yeh SJ, Wen MS, Yeh KH, Wang CC, Lin FC, et al.Algorithm for differentiation of left and right posterior paraseptalaccessory pathway. J Electrocardiol 2004; 37: 75–81.

39. Villacastin J, Almendral J, Medina O, Arenal A, Merino JL, PeinadoR, et al. “Pseudodisappearance” of atrial electrogram during ortho-dromic tachycardia: New criteria for successful ablation of concealedleft-sided accessory pathways. J Am Coll Cardiol 1996; 27: 853–859.

Electrophysiological Characteristics and Radiofrequency ...

Documents

Transcript of Electrophysiological Characteristics and Radiofrequency ...