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Journal of the American College of Cardiology Vol. 44, No. 8, 2004© 2004 by the American College of Cardiology Foundation ISSN 0735-1097/04/$30.00P

Heart Rhythm Disturbances

he Electrocardiogram During Sinus Rhythmnd Tachycardia in Patients With Mahaim Fibershe Importance of an “rS” Pattern in Lead IIIduardo Back Sternick, MD,* Carl Timmermans, MD,† Eduardo Sosa, MD,‡ernando E. S. Cruz, MD, FACC,§ Luz-Maria Rodriguez, MD, FACC,† Márcio Fagundes, MD,§uiz M. Gerken, MD,* Hein J. J. Wellens, MD, FACC†elo Horizonte, São Paulo, and Rio de Janeiro, Brazil; and Maastricht, The Netherlands

OBJECTIVES The purpose of the study was to identify the electrocardiographic (ECG) characteristics of theMahaim fiber.

BACKGROUND Mahaim fibers are slowly conducting accessory pathways reaching into the right ventricle.They often play a role in tachycardias.

METHODS We retrospectively analyzed 40 patients with Mahaim fibers. Five patients had associatedWolff-Parkinson-White syndrome and were excluded from the study. Two patients had ashort atrioventricular decremental accessory pathway and were also excluded. The remaining33 patients had a tachycardia with anterograde conduction over a Mahaim fiber. Twenty werefemale. Their mean age was 24 � 10 years.

RESULTS The most common pattern of minimal preexcitation during sinus rhythm was an rS patternin lead III. This was found in 20 patients. There was a match between the presence of rS inlead III during sinus rhythm and left axis deviation during tachycardia with anterogradeconduction over the Mahaim fiber. After ablation, a different QRS pattern emerged in leadIII, indicating the absence of conduction over the Mahaim fiber. To obtain information onthe prevalence of an rS pattern in lead III in age-matched controls with palpitations andwithout structural heart disease, the 12-lead ECG of 200 young individuals were examined.An rS pattern in lead III was found in 6%.

CONCLUSIONS A narrow QRS with an rS pattern in lead III during sinus rhythm in a patient with a historyof palpitations should alert the physician to the possibility of a Mahaim fiber. Duringtachycardia, these patients typically show a left bundle branch block-like QRS complex withleft axis deviation. (J Am Coll Cardiol 2004;44:1626–35) © 2004 by the American College

ublished by Elsevier Inc. doi:10.1016/j.jacc.2004.07.035

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ccessory pathways with long and decremental anterogradeonduction have been the subject of extensive debate aboutheir anatomic structure (1–4), location (5–7), related ar-hythmias (8,9), electrophysiologic properties (10–12), ab-ative techniques (13,14), and automaticity (15). Less atten-ion has been given to the 12-lead electrocardiogramECG), especially to the ECG during sinus rhythm. Theatter is considered to be normal in the majority of patientsith atriofascicular pathways and patients with long atrio-entricular (AV) decrementally conducting accessory path-ays. Minimal preexcitation is reported to occur from 0% to0% (13,14,16,17), and apart from the absence of q waves inhe left precordial leads (18), no specific QRS pattern haseen described. The purpose of this article is to report onCG findings in a large series of patients with the Mahaimber during sinus rhythm and tachycardia, with emphasis

From the *Biocor Instituto, Belo Horizonte, Brazil; †University Hospital,aastricht, Maastricht, The Netherlands; ‡Instituto do Coração, Faculdade deedicina, Universidade de São Paulo, São Paulo, Brazil; and the §Instituto Nacional

e Cardiologia Laranjeiras, Ministério da Saúde, Rio de Janeiro, Brazil.

iManuscript received April 12, 2004; revised manuscript received May 28, 2004,

ccepted July 14, 2004.

n a particular ECG pattern in lead III during sinushythm.

ETHODS

tudy population. We retrospectively analyzed 12-leadCGs from 40 patients with anterograde conduction over

ccessory pathways with long conduction times and decre-ental properties during both sinus rhythm and tachycar-

ia. Five patients also had anterogradely, rapidly conductingccessory pathways and were excluded from the study. Twoatients with a short AV decremental pathway were alsoxcluded from this series.

efinition of terms. We used the eponym Mahaim fibersn this study as a synonym of accessory pathways with longnd decremental properties with a long anatomic course toither atriofascicular pathways (n � 30) or AV pathwaysn � 3).

Every one of the 33 remaining patients showed electro-hysiologic criteria for a decrementally conducting bypassract during atrial pacing, such as a progressive AH and A-V
nterval prolongation coupled with a decreasing HV interval

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1627JACC Vol. 44, No. 8, 2004 Sternick et al.October 19, 2004:1626–35 The ECG in Patients With Mahaim Fibers

eading to a greater degree of preexcitation with a leftundle branch block (LBBB)-like morphology (5,8,10).There were 20 females and 13 males, with a mean age of

4 � 10 years (range 8 to 52 years). All patients wereeferred for electrophysiologic assessment of a preexcitedachycardia. Preexcited AV node reentrant tachycardia,sing a Mahaim fiber as a bystander, was present in oneatient. One patient had atrial fibrillation with preexcitedRS complexes, and two patients were referred because of

epetitive episodes of unsustained tachycardia caused byutomaticity arising in the Mahaim fiber (Table 1) (9).

Abbreviations and AcronymsAH � atrio-His intervalAV � atrioventricularECG � electrocardiogramHV � His-ventricular intervalLBBB � left bundle branch blockRF � radiofrequency

able 1. Clinical Data

Pt. no. Gender Age (yrs) Site-TA

1 F 31 RL Antidro2 F 32 RL Antidro

AVNRT3 F 19 RPL Antidro4 F 21 RPL Antidro

Orthodr5 M 52 RPL Preexcit6 M 21 RL Antidro7 F 23 RL Antidro8 F 19 A Antidro9 F 23 RL Antidro

10 F 25 RPL Antidro11 M 35 RL Antidro12 F 42 RL Antidro13 F 23 RL Antidro14 F 8 RAL Mahaim15 M 30 RPL Antidro16 F 27 RL Antidro17 F 19 RL Antidro18 M 12 RMS Mahaim19 F 39 RL Antidro20 F 15 RAL AVNRT21 M 13 RL Antidro22 M 15 A Antidro23 F 25 RL Antidro24 M 18 RL Antidro25 F 45 RL Antidro26 M 24 RL Antidro27 M 11 RL Antidro28 M 26 RL Antidro29 M 25 A Antidro30 F 26 P Antidro31 F 31 RL Antidro32 F 22 RL Antidro33 M 17 P Antidro

� anterior; AVRT/Mahaim � reentrant tachycardia with atrioventricular conduct
L � right lateral; RMS � right mid-septal; RPL � right posterolateral; RAL � right an
t the tricuspid annulus (TA); S/RFp/RF-dis � surgery/radiofrequency catheter ablation a

bstein’s disease was diagnosed in four patients. The atrialnsertion of the Mahaim fiber was located by the recordingf a discrete accessory pathway potential in 28 patients andn five patients by assessing the shortest AV interval duringtrial pacing at different sites along the tricuspid annulus.ll patients underwent successful surgical (n � 2) or

adiofrequency (RF) catheter ablation (n � 31). The RFblation was guided by discrete potentials at the tricuspidnnulus (n � 28) and by right ventricular pace mapping inve patients.We also analyzed the 12-lead ECG during sinus rhythm

n 200 individuals with palpitations and without structuraleart disease, matched for age and gender as a controlroup.

Recordings of the 12-lead surface ECG and intracardiaclectrograms were made using the EP Tracer or MS SystemCardioTek BV, Maastricht, The Netherlands).

efinitions of QRS patterns. The ECGs were examinedy two different observers with a magnified lens, and a thirdbserver decided when there was a mismatch classification.

hythmia Ebstein CBTTherapy

(S/RFp/RF-dis)

VRT/Mahaim SVRT/Mahaim RFp

VRT/Mahaim Yes RFpVRT/Mahaim Yes RPS RFpAVRT RFpial fibrillation RFpVRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RFpmaticity RFpVRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RFpmaticity RFpVRT/Mahaim RFpahaim bystander RFp

VRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RFpVRT/Mahaim RF-disVRT/Mahaim Yes SVRT/Mahaim Yes LL RF-disVRT/Mahaim RF-disVRT/Mahaim RF-disVRT/Mahaim RF-disVRT/Mahaim RFpVRT/Mahaim RFp

er a Mahaim fiber; CBT � concealed bypass tract; LL � left lateral; P � posterior;

Arr

mic Amic A

mic Amic Aomiced atrmic Amic Amic Amic Amic Amic Amic Amic A

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ion ov
terolateral; RPS � right posteroseptal; Site � site of ablation of the Mahaim fiber
t the atrial/ventricular insertion.

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1628 Sternick et al. JACC Vol. 44, No. 8, 2004The ECG in Patients With Mahaim Fibers October 19, 2004:1626–35

he following QRS patterns were found: r, rS, RS, Rs, rsR=,sr=, R, qR, QR, QS, qRs, and qRS. A very-low-voltage QRS

Figure 1. Two patients with Mahaim fibers disp

omplex (�0.3 mV) was depicted as small letters (r, rs, or rsr=). (

he QRS complex with a higher voltage was depicted accord-ng to the ratio between the positive (R, r) and negative waves

the rS pattern in electrocardiographic lead III.
laying
q, Q, S, and s). For example, an RS complex was defined by

Figure 2. Five-lead electrocardiogram during sinus rhythm with the pre-ablation electrocardiogram showing the rS pattern in four cases and rsR= in one patient. The post-ablation electrocardiogram showsa clear change in QRS configuration.

1629JACC

Vol.44,No.8,2004Sternick

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October19,2004:1626–35The

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he presence of a QRS complex showing an initially positiveeflection followed by a negative deflection of an even magni-ude. Likewise, an Rs pattern means a QRS complex (�0.3V) with an initial positive deflection followed by a smaller

egative one. A septal q wave was defined as a q wave in surfaceCG leads I, aVL, and V6, with an amplitude �25% of the Rave and a width �0.04 s.tatistical analysis. Data are given as the mean value �D. The significance of differences (p � 0.05) betweenroups of clinical, ECG, or electrophysiologic parametersas assessed by the Student t test or Fisher exact test.

ESULTS

re-ablation 12-lead ECG findings. Minimal preexcita-ion, defined as subtle abnormalities suggesting the pres-nce of preexcitation, with a QRS complex width within

able 2. Electrocardiographic Data of Mahaim Fibers

Pt. no.

Before Mahaim Ablat

Sinus Rhythm

PRiQRS

WidthLead III

Beforeq-I

Beforeq-V6

Before

1 0.13 0.11 rS No No2 0.11 0.11 rS No No3* 0.12 0.08 rS No No4* 0.14 0.08 qRs No No5 0.12 0.09 rS No No6 0.12 0.09 qR No No7 0.11 0.08 rS No No8 0.13 0.08 qR Yes No9 0.10 0.09 rS Yes Yes

10 0.12 0.1 rS No No11 0.14 0.09 rS Yes No12 0.11 0.1 rS No No13 0.13 0.12 rS No Yes14 0.14 0.09 rS No No15 0.15 0.09 rS Yes Yes16 0.15 0.08 qR No No17 0.14 0.08 qR No Yes18 0.10 0.11 rS No No19 0.13 0.11 rS* Yes No20 0.12 0.1 rS No No21 0.14 0.08 qR No Yes22 0.12 0.09 qR Yes Yes23 0.12 0.1 rS No No24 0.11 0.1 rS No No25 0.20 0.09 rS No No26 0.10 0.1 rS No No27* 0.12 0.1 rS Yes Yes28* 0.12 0.1 rS Yes Yes29 0.12 0.09 rsR= No No30 0.14 0.08 qR No No31 0.12 0.09 qR No No32 0.14 0.08 qR Yes Yes33 0.14 0.09 rsR= No No

Patient with Ebstein’s disease. Bold characters indicate patients with minimal preexAP � accessory pathway; PRi � PR interval; pre/post � before/after radiofreque

he normal range (�0.12 s), but with a short HV interval s

�35 ms), was present during sinus rhythm in 24 patients72%) (Fig. 1). The PR interval was not significantlyifferent when comparing patients with (125 � 21 ms)nd without (132 � 9 ms) minimal preexcitation (p �S).We found two patterns of the QRS complex (Fig. 2)

uring sinus rhythm: the most common one being an rSonfiguration in lead III. This was found in 20 patients. Thether pattern in lead III—an rsR=—was found in twoatients. In the presence of an rS pattern in lead III, no qave was found in lead I in 15 patients (and in 8 patients in

ead V6). Minimal preexcitation, as manifested by thebsence of a q wave in lead I (without rS in lead III), waseen in only two patients (Patient #8 and #16) (Table 2).

In three patients, minimal preexcitation was not alwaysemonstrated, as documented by 12-lead ECGs taken onifferent days. Variability of minimal preexcitation on the

After Ablation

Tachycardia Sinus Rhythm

ad III Axis°QRS

Width (ms)Lead III

Afterq-I

Afterq-V6

After

rS 0 120 qR No YesrS �30 130 rs No NorS �45 140 qR No NorS �45 130 qR No NoQS �45 130 rs No NorS �30 120 qR No NorS �15 120 qR No YesR 60 130 qR No YesrS �45 130 Rs No YesQS �60 120 qR Yes YesrS �15 120 rsr= Yes YesrS 30 130 qR No NorS �30 120 qR No YesrSr= 0 120 qR No NorS �60 120 qR No NorS �45 120 qR No YesrS �30 120 qR No YesQS �60 120 qR No YesrS �45 120 rS Yes NoQS �45 130 qR Yes YesrS 0 130 qR No YesR 60 130 qR Yes Yesrs �30 120 qR No YesrS �30 130 qR Yes YesQS �30 120 qR No NorS 0 120 qR Yes YesrS �30 140 rsR= Yes YesrS �75 120 RS Yes YesRS 15 140 QR No NoQS �60 120 qR No NorS �60 120 qR No NorS �30 140 qR Yes YesrS �30 140 qR No No

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ntracavitary signals, Mahaim potential recording, andight bundle and His bundle electrograms. We foundhat the AM interval (i.e., atrium-proximal Mahaim poten-ial interval) was always 20 to 40 ms shorter than the AHnterval in patients with minimal preexcitation. In patientsithout preexcitation, the AH interval was shorter than theM interval (Fig. 4).he ECG during tachycardia. We analyzed 29 patientsith a circus movement tachycardia with anterograde con-uction over the Mahaim fiber, 1 patient with AV nodee-entrant tachycardia with bystander Mahaim conduction,

with atrial fibrillation with anterograde conduction overhe Mahaim fiber, and 2 with automatic tachycardias arisingn the Mahaim fiber. During circus movement tachycardia,he cycle length ranged from 430 to 250 ms. The QRSidth during tachycardia (Table 2) varied from 120 to 140s. All patients had a monophasic R wave in lead I, and 30

f 33 patients had rS in lead V1 during tachycardia (3

igure 3. (A) ECG showing minimal preexcitation (rsR= pattern in lead IIIerapamil shows sinus rhythm with AV conduction over the Mahaim fibe

atients had QS in V1). p

omparison between ECG during sinus rhythm anduring tachycardia with anterograde conduction over the

ahaim fiber. In all 20 patients with an rS pattern in leadII, we found a negative QRS complex in the same leadeither rS or QS pattern) during tachycardia. Also, theatient with atrial fibrillation showed a negative QRSomplex. There were nine patients without the rS pattern inead III during sinus rhythm, which showed left axiseviation during tachycardia. Three patients showed con-ordance between the absence of an rS pattern during sinushythm and their tachycardia QRS pattern (all three pa-ients had an anterior Mahaim) (Fig. 5).ost-ablation 12-lead ECG. In the 24 patients showinginimal preexcitation in the 12-lead ECG, six patternsere observed in lead III during sinus rhythm afterahaim ablation. The most common QRS configuration

as the qR or QR pattern found in 18 patients, Rs in oneatient, RS in one patient, rs in two patients, rsR= in one

in the first three QRS complexes. (B) Electrocardiogram after intravenousa long PR interval and overt pre-excitation.

atient, and rsr= in one patient. Assessment of the left

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recordial leads after ablation showed that in only nineatients, the previous ECG pattern changed with theevelopment of a small q wave, whereas the other patientshowed the same pre-ablation QRS complex. Figure 2ives examples when comparing the QRS before and afterblation.orrelation between ECG findings and Mahaim fiber

ocation. The rS morphology in lead III was not seen in thehree cases with an anteriorly located Mahaim or the twoatients with a posterior Mahaim fiber. The distribution ofhe atrial end of the Mahaim fiber in the 20 patients with anS pattern in lead III during sinus rhythm along thericuspid annulus is depicted in Figure 6. It is of interest thathe atrial end of the Mahaim fiber with an rS pattern in leadII can be found over a large area around the tricuspidnnulus, from the anterolateral to the posterolateral andid-septal region.resence of an rS pattern in lead III during sinus rhythm

n 200 matched controls. We did a survey in 200 youngndividuals referred because of palpitations. Twelve (6%) of00 matched controls (56% females; mean age 23 � 12ears) without heart disease and without a history of

igure 4. (Left) Patient no. 6 without preexcitation showing a shorter atrhorter than the AH interval, resulting in minimal preexcitation with an r

alpitations showed an rS pattern in lead III during sinus o

hythm (Fig. 7). However, all of them had a q wave in lead(qR or qRs pattern).

ISCUSSION

hen accessory AV pathways have conduction times ap-roaching that of the normal AV conduction system, littler no preexcitation may be present during sinus rhythm.he reported incidence of minimal preexcitation on the2-lead ECG during sinus rhythm in patients with decre-entally conducting accessory pathways is low. Bardy et al.

16) and Klein et al. (19) did not find it in any of theiratients. McClelland et al. (13) reported that only one ofheir 26 patients displayed preexcitation on the 12-leadCG. When we realized the prevalence of the rS pattern in

ead III in our patients, we examined previous reportsealing with decrementally conducting bypass tracts. Weid find the rS pattern in lead III on many ECGs consid-red as normal in cardiology journals (17,19,20) and text-ooks (21,22). This suggests that the reported low figures ofbnormal ECGs in patients with Mahaim bypass tracts is annderestimation. Some authors acknowledged the presence

interval (AH) than AM interval. (Right) Patient no. 2 showing an AMtern in lead III.

f minimal preexcitation in 25% to 50% of their patients

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14,18). We found an incidence of 72% of minimal preex-itation, mainly in the presence of an rS pattern in lead III60%). It should be stressed that in these patients, there iso classic delta wave. It is of interest that the rS pattern wasound in patients with decremental accessory pathways havingheir atrial end over a very large area around the tricuspidnnulus, from anterolateral to posterolateral, as well as in thenly patient with a mid-septal location (Fig. 6). This supportsventricular insertion in a small anterolateral area in the right

entricle in or close to the exit of the right bundle branch andlso explains (when ventricular activation starts at this site) thebsence of a q wave in lead I.

To validate the rS and rsR= as abnormal patterns in leadII due to preexcitation of a small region of the rightentricle, it was crucial to show a positive relationshipetween those patterns in lead III during sinus rhythm andeft axis deviation during tachycardia with anterogradeonduction over the Mahaim fiber (Fig. 1). All 20 patientsith an rS in lead III had left axis deviation (�0°) during

achycardia. Another important step in validation is to showclear change in QRS complex configuration after ablationf the decremental accessory pathway. Figure 2 depicts mostf the patterns of QRS that emerged after successfulblation of the Mahaim fiber.

The fact that nine patients did not show an rS pattern inead III during sinus rhythm but an LBBB-like QRS witheft axis deviation during tachycardia can be explained bympulse conduction over the Mahaim fiber during sinushythm slower than impulse conduction over the normalV conduction system. We, like other authors (23), founday-to-day variability in the expression of minimal preexci-ation. This is different from “intermittent” preexcitationhat may occur in rapidly conducting accessory pathwaysith long anterograde refractory periods. Our patients withariable expression of preexcitation did not have longefractory periods of their accessory pathway. There is onease report of sudden death in a patient with similar findings

igure 6. Proportion of patients with an rS pattern in lead III during sinushythm in relation to the location of the atrial end of the Mahaim fiberlong the tricuspid annulus. CS � coronary sinus; MS � mid-septal; RA

right anterior; RAL � right anterolateral; RL � right lateral; RP �ight posterior; RPL � right posterolateral.

igure 5. Case 29: this patient had an anterior Mahaim fiber and an

24). Conduction over Mahaim fibers can be so slow that no

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entricular preexcitation occurs even during atrial pacing.till, these so-called latent Mahaim’s are capable of being

nvolved in antidromic tachycardias (25).re all Mahaim fibers inserting close to or in the rightundle branch? Some Mahaim fibers are probably not

nserting in that region. Our three patients with anteriorahaim did not show an rS in lead III nor left axis

eviation during tachycardia, suggesting that in those fibers,he ventricular insertion is not in the vicinity of the rightundle branch (6) (Fig. 5).eptal q waves. In our population, lead I was moreensitive for minimal preexcitation than lead V6. In patientsith atriofascicular pathways inserting close to the apex,entricular activation proceeds from an apical toward a basalirection, resulting in a q wave in lead V6. Minimalreexcitation due to left-sided accessory pathways can beetter appreciated in lead V6, which has been shown to beore sensitive than leads I and aVL (26).

S as a normal pattern in lead III. It has been shown (27)hat an rS pattern in lead III can be found in normalndividuals. This may occur during posterior displacementf the apex leading to S waves in leads I, II, and III (S1S2S3

attern [28]) and in counterclockwise rotation of the heartesulting in a qR in lead I and rS in lead III. However, inhose situations, a normal q wave in lead I is likely to beresent. In our survey of 200 ECGs from young individualsith palpitations, we found the rS pattern in lead III in 6%,ut always associated with a q wave in lead I. No individualhowed an rS pattern in lead III combined with the absencef a q wave in lead I, a pattern that seems specific foratients with a Mahaim fiber.tudy limitations. SPECIFICITY OF THE rS PATTERN IN THE

ENERAL POPULATION. The finding of an rS pattern inead III in 60% of the patients with Mahaim fibers isignificantly higher than its occurrence in young personsith palpitations (p � 0.0001).Mahaim fibers comprise �3% of the overt accessory

athways (29). Based on the prevalence of accessory path-ays in the general population (30) (0.2%), the prevalencef Mahaim fibers would be 0.5 to 1:10.000. The specificityf an rS pattern in lead III associated with the absence of aeptal q wave will be close to 90% (if we assume one falseositive in 1,000 individuals), albeit the sensitivity decreaseso 45%.

onclusions. In young patients with tachycardias, thending of a narrow QRS with an rS pattern in lead III

Figure 7. Lead III pattern in 20

uring sinus rhythm should raise the suspicion of the1

resence of a Mahaim fiber, especially in those showing anbsence of q wave in lead I.

cknowledgmente would like to thank Sávia Bueno, MD, for data

ollection.

eprint requests and correspondence: Dr. Eduardo Back Ster-ick, rua Correias 281/301, Belo Horizonte, Minas Gerais, 30315-40 Brazil. E-mail: [email protected].

EFERENCES

1. Mahaim I, Bennatt A. Nouvelle recherches sur les connexions su-perieures de la branche gauche du faisceau de His-Tawara avec cloisoninterventriculaire. Cardiologia 1938;1:61–20.

2. Becker AE, Anderson RH. The anatomical substrates of Wolff-Parkinson-White syndrome: a clinico-pathologic correlation in sevenpatients. Circulation 1978;57:870–9.

3. Anderson RH, Becker AE. Stanley Kent and accessory atrioventricularconnections. J Thoracic Cardiovasc Surg 1981;81:649–58.

4. Guiraudon CM, Guiraudon GM, Klein GJ. Histologic evidence for anaccessory atrioventricular pathway with AV-node-like morphology.Circulation 1988;78 Suppl II:II40.

5. Klein GJ, Guiraudon GM, Kerr CR, et al. ‘Nodoventricular’ accessorypathway: evidence for a distinct accessory atrioventricular pathwaywith atrioventricular node-like properties. J Am Coll Cardiol 1988;11:1035–40.

6. Peinado R, Merino JL, Ramı́rez L, et al. Decremental atriofascicularaccessory pathway with bidirectional conduction: delineation of atrialand ventricular insertion by radiofrequency current application. J Car-diovasc Electrophysiol 2001;12:489–92.

7. Hluchy J, Schickel S, Jörger U, et al. Electrophysiologic characteristicsand radiofrequency ablation of concealed nodofascicular and leftanterograde atriofascicular pathways. J Cardiovasc Electrophysiol2000;11:211–7.

8. Gallagher JJ, Smith WM, Kassell JH, et al. Role of Mahaim fibers incardiac arrhythmias in man. Circulation 1981;64:176–89.

9. Sosa E, Scanavacca M. Repetitive nonsustained wide QRS complextachycardia: what is the tachycardia mechanism? J Cardiovasc Elec-trophysiol 2001;12:977–8.

0. Wellens HJJ. Electrical Stimulation of the Heart in the Study andTreatment of Tachycardias. Baltimore, MD: University Park Press,1971.

1. Tchou P, Lehmann MH, Jazayeri M, et al. Atriofascicular connection ora nodoventricular Mahaim fiber? Electrophysiologic elucidation of thepathway and associated reentrant circuit. Circulation 1988;77:837–48.

2. Porkolab F, Alpert B, Scheinman MM. Failure of atrial prematurebeats to reset atriofascicular tachycardia. Pacing Clin Electrophysiol1999;22:528–30.

3. McClelland JH, Wang X, Beckman KJ, et al. Radiofrequency catheterablation of right atriofascicular (Mahaim) accessory pathways guided byaccessory pathway activation potentials. Circulation 1994;89:2655–66.

4. Heald SC, Davies DW, Ward DE, et al. Radiofrequency catheterablation of Mahaim tachycardia by targeting Mahaim potentials at thetricuspid annulus. Br Heart J 1995;73:250–7.

ng individuals with palpitations.

5. Sternick EB, Gerken LM, Vrandecic MO. Appraisal of ‘Mahaim’automatic tachycardia. J Cardiovasc Electrophysiol 2002;13:244–9.

1

1

1

1

2

2

2

2

2

2

2

2

2

2

3


6. Bardy GH, Fedor JM, German LD, et al. Surface electrocardiographicclues suggesting presence of a nodofascicular Mahaim fiber. J Am CollCardiol 1984;3:1161–8.

7. Ellenbogen KA, Ramirez NM, Packer DL, et al. Accessory nodoven-tricular (Mahaim) fibers: a clinical review. Pacing Clin Electrophysiol1986;9:868–84.

8. Haissaguerre M, Cauchemez B, Marcus F, et al. Characteristics of theventricular insertion sites of accessory pathways with anterogradedecremental conduction properties. Circulation 1995;91:1077–85.

9. Klein LS, Hackett K, Zipes DP, et al. Radiofrequency catheterablation of Mahaim fibers at the tricuspid annulus. Circulation1993;87:738–47.

0. Shimizu A, Ohe T, Takaki H, et al. Narrow QRS complex tachycardiawith atrioventricular dissociation. Pacing Clin Electrophysiol 1988;11:384–93.

1. Mittleman RS, Huang SKS. Ablation of Mahaim fibers. In: HuangSKS, editor. Radiofrequency Catheter Ablation of Cardiac Arrhyth-mias: Basic Concepts and Clinical Application. Armonk, NY: Futura,1995:352.

2. Josephson ME. Preexcitation syndromes. In: Clinical Cardiac Elec-trophysiology: Techniques and Interpretations. Philadelphia, PA:
Lippincott Williams & Wilkins, 2002:404.
3. Ott P, Marcus FI. Familial Mahaim syndrome. Ann NoninvasEletrocardiol 2001;6:272–5.

4. Gmeiner R, Keung CK, Hammer I, et al. Tachycardia caused by anaccessory nodoventricular tract: a clinico-pathologic correlation. EurHeart J 1984;5:233–42.

5. Davidson NC, Morton JB, Sanders P, et al. Latent Mahaim fiber as acause of antidromic reciprocating tachycardia: recognition and success-ful radiofrequency ablation. J Cardiovasc Electrophysiol 2002;13:74–8.

6. Bogun F, Kalusche D, Li YG, et al. Septal Q waves in surfaceelectrocardiographic lead V6 exclude minimal ventricular preexcita-tion. Am J Cardiol 1999;84:101–4.

7. Tranchesi J, Moffa PJ. Electrocardiograma Normal e Patológico. SãoPaulo, Brazil: Atheneu Editora LTDA, 1983:86–91.

8. Pileggi F, Tranchesi J, Grandisky B, et al. Análise vectorcardiográficada ativação ventricular em indivı́duos com eletrocardiograma do tipoS1 S2 S3. Arq Bras Cardiol 1961;14:373–8.

9. Miller JM, Olgin JE. Catheter ablation of free-wall accessory pathwaysand ‘Mahaim’ fibers. In: Zipes DP, Haissaguere M, editors. CatheterAblation of Cardiac Arrhythmias. 2nd edition. Armonk, NY: Futura,2002:277–303.

0. His RG, Lamb LE. Electrocardiographic findings in 122,043 individ-
uals. Circulation 1962;25:947–61.

the electrocardiogram during sinus rhythm and tachycardia ... · ecg leads i, avl, and v 6, with an...

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