Europace (2005) 7, 40e49
Radiofrequency ablation of atrial arrhythmias
after previous open-heart surgery
A. Nabar), C. Timmermans, A. Medeiros, K. Polymeropoulous,
H.J.G.M. Crijns, L.M. Rodriguez1
Department of Cardiology, Cardiovascular Research Institute Maastricht, Academic Hospital
Maastricht, P.Debyelaan 25, 6202 AZ, Post box 5800, Maastricht, Limburg, The Netherlands
Submitted 24 October 2003, and accepted after revision 22 September 2004
KEYWORDS
catheter ablation;
mapping;
tachyarrhythmias;
post open-heart
surgery
tachyarrhythmias
Abstract Aim To report the results of ablation of atrial arrhythmias (AA) after
previous open-heart surgery.
Methods Nineteen patients [50 G 11 years, 11 women] underwent ablation of
symptomatic AAs after previous open-heart surgery. In 11 patients mapping was
performed using conventional multielectrode catheters. In the other eight patients
CARTO electro-anatomical mapping system was used to supplement conventional
mapping.
Results After conventional mapping, 10/11 patients (91%) were found to have
typical atrial flutter (AFL). The cavotricuspid isthmus was successfully ablated in
these 10 patients. CARTO combined with conventional mapping showed that 7 of 8
patients had one macro-reentry right atrial circuit. The remaining patient had two
focal atrial tachycardias. CARTO-guided ablation was successful in all eight patients
(100%). After follow-up of 12 G 11 months, 2/18 patients (11%) had recurrence of
either the same (n Z 1) or a new (n Z 1) AA.
Conclusions AAs after previous open-heart surgery can be ablated successfully
(O90%) with a low recurrence rate (11%) at 1-year follow-up. Typical AFL was found
frequently (14/19 patients, 72%). This could be ablated successfully, often, after
conventional mapping alone. CARTO helps to uncover peri-scar reentry and guide
the ablation by creating a line of block connecting the scar to another landmark
(unconventional isthmus).
ª 2004 The European Society of Cardiology. Published by Elsevier Ltd. All rights
reserved.
) Corresponding author. Tel.: C31 43 387 5093; fax: C31 43 387 5104.
E-mail addressess: [email protected] (A. Nabar), [email protected] (L.M. Rodriguez).
1
Tel.: C31 43 387 7207; fax: C31 43 387 5104.
1099-5129/$30 ª 2004 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.eupc.2004.09.009
Ablation of atrial arrhythmias after open-heart surgery
Introduction
Various right atrial macro-reentrant circuits such as
counterclockwise and clockwise atrial flutter (AFL)
along the tricuspid annulus (TA) [1], lower-loop and
upper-loop reentry around the vena cavae [2], and
right atrial free wall flutter [3] have been mapped
in the clinical electrophysiological laboratory using
conventional multielectrode catheters. Reentry
around an atriotomy scar, prosthetic material such
as an atrial septal patch, or simply along the TA has
been observed in patients developing atrial arrhythmias (AA) late after open-heart surgery
[4e12]. Double-loop reentry implies a circuit that
is simultaneously around two anatomical barriers
and shares a common trajectory in a part of the
circuit [7e13]. CARTO electro-anatomical mapping
can precisely outline the reentrant circuit in relation to a post-surgical scar and other anatomical
barriers [7e9,11e13]. Akar et al. found multiple
reentry circuits coexisting and concluded that the
surface ECG failed to provide adequate discrimination [10]. Recent studies support that AAs can be
terminated by ablating linearly (between the scar
and the nearest anatomical barrier) [4,5,9e12] or
focally (in the ‘‘return channel’’ within the scar)
[7,8] across the reentrant pathway. We sought to
report the results of radiofrequency ablation of AAs
after previous open-heart surgery.
Methods
Patient population
The present study is a retrospective analysis of 19
patients who underwent an electrophysiological
Table 1
41
study and radiofrequency ablation of symptomatic
AAs after previous open-heart surgery [14 G 12
years (range 6 monthse40 years)], see Table 1.
During the study period, extending from June 1994
to November 2001, 267 other patients in our
institution underwent ablation of a typical AFL.
CARTO electro-anatomical mapping system was
available only during the latter part of this study.
The mean age of our study population was 50 G 11
years (range 21e61 years) and included 11 women.
Eight patients had undergone repair/replacement
of mitral (n Z 5), aortic (n Z 1) or both (n Z 2)
heart valves. Surgical closure of the atrial septum
was performed for a congenital defect in eight
patients and after the excision of a left atrial
myxoma in one patient. One of these latter eight
patients, known to have pre-operative AFL, during
the surgical closure of atrial septal defect had
undergone linear cryoablation between the lower
end of the right atriotomy and the inferior vena
cava. One patient underwent a staged-correction
of Ebstein’s anomaly and Rastelli’s repair was
performed for d-transposition of great arteries
(with ventricular septal defect and pulmonary
stenosis) in one other patient. Mean age at the
time of the open-heart surgery was 37 G 16 years
(range 11e56 years).
Clinical profile of the documented AAs
In the 19 patients included, 25 AAs were clinically
documented. Six patients had two AAs. Electrocardiographically, atrial tachycardia (AT) is recognized by discrete P waves separated by a clearly
defined isoelectric baseline, while an ECG of AFL
shows a characteristic ‘‘saw tooth’’ pattern or
Details of the cardiac surgery in 19 patients
Cardiac surgery
Patients (n)
Valvular
(1) Mitral VP
(2) Mitral VR
(3) Aortic VR
(4) OMC C aortic VP
(5) Mitral VR C aortic VP
8
1
4
1
1
1
Atrial septal defect closure
(1) Direct
(2) Patch
(3) Not known
9
5
2
2
Corrective repair of CCHD
(1) Ebstein’s anomaly
(2) d-TGA, VSD, PS
2
1
1
Remarks
With tricuspid VP
With tricuspid VP (1), prior CMC (3)
With cryoablation, from atriotomy to IVC (1)
With left atrial myxoma excision (1)
Staged: first atrial septal defect closure, second tricuspid VP
Rastelli’s repair. Prior Blalock-Taussig shunt
CMC, closed mitral commissurotomy; CCHD, complex congenital heart disease; d-TGA, VSD, PS, d-transposition of great arteries with
ventricular septal defect and pulmonary stenosis; OMC, open mitral commissurotomy, VP, valvuloplasty; VR, valve replacement.
42
broad positive deflections depending on the direction of rotation (respectively, counterclockwise
or clockwise along the TA) of the typical AFL
circuit [1,14,15]. Based on these ECG criteria, 18
of the 25 clinically documented AAs were classified
as AFL and the remaining seven as AT. In 13
patients, AAs were documented for the first time,
6 years (median, range 3e33 years) after the index
surgery. AAs were known pre-operatively (n Z 4)
or were treated since the early post-operative
period (n Z 2) in the remaining six patients. More
than half of the patients (12/19 patients, 63%) had
associated atrial fibrillation. AAs were resistant
to 3 G 1.3 (range 1e5) anti-arrhythmic drugs, including amiodarone in 11 patients. In 13 patients,
prior to considering ablation, various non-pharmacological options, including external and/or internal cardioversion, Atrioverter device (one
patient), or AV-node ablation and dual chamber
pacemaker implantation (one patient), were tried.
Electrophysiological study
Informed consent was obtained and all procedures were performed in a post-absorptive state.
Anti-arrhythmic drugs were not stopped prior to
the study. AAs that were incessant at the time of
the study or those that were induced during the
study and electrocardiographically found to be
identical to the one previously documented were
mapped and targeted for ablation. AAs were
mapped using conventional techniques in 11
patients. Conventional mapping involved the use
of a duodecapolar Halo catheter placed along the
TA, a quadripolar catheter in the His bundle
position and a decapolar catheter introduced in
the coronary sinus and placed so that its proximal
bipole was located at the ostium. CARTO electroanatomical mapping (Biosense-Cordis-Webster)
[7e9,11,12,15,16] was used to supplement conventional mapping in the remaining eight patients. The right atrium was mapped by
acquiring a mean of 148 G 85 (59e190) points.
The mean volume of the right atrial map was
129 G 42 (42e175) ml. Macro-reentry was diagnosed when atrial activation times were sequentially distributed over the arrhythmia cycle length
in a circular manner. The slow conducting part of
the circuit was identified retrospectively. A focal
mechanism was diagnosed when atrial activation
spread from the site of earliest activity in a radial
manner. Atrial sites recording double potentials,
fractionated electrograms and/or a bipolar voltage %0.1e0.3 mV were empirically designated as
scar [8,11]. The left atrium was not mapped.
A. Nabar et al.
Radiofrequency ablation
‘‘Conventional’’ cavotricuspid isthmus (posterior;
TA-inferior vena cava or septal; TA-coronary sinus)
was ablated in patients with a typical AFL. Bidirectional isthmus conduction block and noninduciblity during isoprenaline infusion (1e3 mg/min)
was judged as a procedural success [17]. Linear
ablation across the peri-scar reentrant pathway,
connecting the scar to an anatomical barrier e
‘‘unconventional’’ isthmus, was performed using
the CARTO system [5]. Such an unconventional
isthmus was targeted, in some patients with typical
AFL, if the flutter had recurred after the ablation of
conventional cavotricuspid isthmus during a previous procedure. Each radiofrequency pulse was
delivered for 90 s with the temperature cut-off
preset at 70 (C. After ablation, if the targeted AA
was not inducible, CARTO mapping was repeated to
verify conduction block across the ablation line.
Follow-up
Follow-up was conducted at the arrhythmia clinic, 8
weeks after the procedure and at 3-monthly intervals thereafter, or was obtained from the referring
cardiologist at the end of the study. Eight patients
who had coexisting atrial fibrillation continued to
take anti-arrhythmic drugs. Additional ECGs and
Holter studies were obtained when patients had
complaints suggestive of arrhythmia recurrence.
Statistical analysis
All data were expressed as mean G SD, median
and range.
Results
Electrophysiological study and
radiofrequency ablation using
conventional mapping alone (n [ 11)
The ECG suggested AFL in 10 patients, while an AT
was considered in the remaining one patient
(Table 2). The mean cycle length was
288 G 44 ms (range 210e340 ms). Conventional
mapping in the former 10 patients showed sequential activation along the TA spanning a large part
(O80%) of the flutter cycle length. Activation
along the TA was counterclockwise in eight
patients and was associated with negative flutter
waves in the inferior leads; and clockwise in two
patients with positive flutter waves in the same
5
6
7b
8
IVC, inferior vena cava; SVC, superior vena cava. All ablation procedures were successful.
a
Patient 4 underwent two CARTO procedures.
b
In patient 7, during the electrophysiological study, the rotation of para-tricuspid AFL altered between CW and CCW.
TAeIVC (2.4)
ScareTA (2.1)
TAe IVC(1.5)
High anterior,
low posterior
Clockwise e along the TA Anterior (0.4)
2 e loops
Septal (0.3)
Only voltage map
Intra-scar (0.2)
Focal, focal
e
Septal
Atriotomy
Septal, posterolateral
Septal, posterolateral
Clockwise
Clockwise
Both
Bi-directional,
bi-directional
Septal
Counterclockwise Septal
240
4a AFL
II (Positive),
III (negative)
AT
Positive
AFL
Positive
AFL
Negative
AT1, AT2 Positive,
undetermined
330
320
280
550, 400
SVCescar (3.4)
AtriotomyeTA (4.3)
SVCescar (3.7)
AtriotomyeIVC (2.6)
TAeIVC (0.4)
e
Inferior to the
scar (0.2)
ScareTA (0.3)
335
330
The 12-lead ECG suggested AT in five patients and
AFL in the remaining three patients (Table 3). The
mean cycle length was longer, 351 G 87 ms (range
240e550 ms). In patients 1e4, the CARTO system
was used for mapping an AA that had recurred
after the ablation of cavotricuspid isthmus during
a previous procedure. In two of these patients, the
ECG morphology of the recurrent AA was different
from the one previously ablated. Previous cavotricuspid isthmus ablation being successful in only
one of these two patients. In the remaining two
patients, the ECG morphology of the recurrent AA
was identical to the one previously ablated. One
patient had recurrence despite a previously successful cavotricuspid isthmus ablation, while ablation had failed to terminate the tachycardia in the
second patient. Inadequate arrhythmia localization with conventional multielectrode catheters
Positive
Positive
Electrophysiological study and RF
ablation using conventional and CARTO
electro-anatomical mapping (n [ 8)
AT
AT
leads. Ablation of the cavotricuspid isthmus was
successful in all the 10 patients. In the remaining
one patient, in whom the ECG suggested an AT, the
polarity of the P wave was positive in the inferior
leads and in lead V1 and negative in leads I and
aVL. Further, based on conventional mapping, the
estimated biatrial activation time was 70 ms. This
was only 21% of the tachycardia cycle length
(330 ms). By inference, these findings suggest that,
this arrhythmia could have been a focal AT arising
from the left atrium. Ablation was not successful
in this patient.
2
3
Procedural success
20 (8)
(range 6e35)
10/11 (91%)
Superioreanterioreinferior Clockwise e along
the TA
Counterclockwise Atriotomy, septal
Only voltage map
Counterclockwise Septal
Septal
Radiofrequency pulses delivered
Clockwise
2
6
3
350
Ablation catheter used
4 mm-tip
8 mm-tip
Both
Positive
8
1
2
AT
Ablated cavotricuspid isthmus
Posterior
Septal
Both
1
3
2
6
Table 3
Radiofrequency ablation during
AFL
Coronary sinus pacing
Both
Results of radiofrequency ablation after conventional and CARTO electro-anatomical mapping in eight patients
Table 2 Results of radiofrequency ablation after
conventional mapping in 11 patients
Conventional
CARTO electro-anatomical mapping of the right atrium
mapping e along Location of
Location of the
Slowest part of the
Length of the ablated
the Halo catheter the scar
reentry circuit
circuit (velocity, m/s) isthmus (length, cm)
43
No ECG
P or F waves Cycle
diagnosis in leads II, III, length
aVF
(ms)
Ablation of atrial arrhythmias after open-heart surgery
44
was the cause of failed ablation. CARTO mapping
system was used de novo in patients 5e8.
After combined conventional and CARTO mapping, seven out of eight patients were found
to have one macro-reentrant circuit in the right
atrium. The macro-reentrant circuit was delineated almost completely (92% G 11%) in five of
the seven patients. A clockwise typical AFL and a
circuit around the septal scar were found in two
patients each. A double-loop reentry, simultaneously around the lateral right atriotomy scar
and the TA, was recognized in one patient,
see Figs. 1e3. In the remaining two patients
only a voltage map, during sinus rhythm, could
be constructed. In both these patients, the
diagnosis of typical AFL was based on conventional
mapping.
Ablation was performed during sinus rhythm in
five patients. An unconventional isthmus, between
the scar and the TA/vena cava, was ablated in five
patients; while in the other two patients the
conventional posterior isthmus was ablated. Thus
the reentry circuit could be interrupted successfully in all seven patients, albeit after two CARTO
A. Nabar et al.
procedures in one patient. Retrospective analysis
of the CARTO maps showed that the ablated
isthmus did not transect the slowest conducting
part of the macro-reentry circuit. The mean length
of the ablated isthmus was 2.8 G 0.9 cm (range
1.5e4.3 cm). Linear ablation required a mean of
23 G 16 radiofrequency pulses.
The remaining one patient had two focal ATs
(Figs. 4 and 5). A focal mechanism was suspected
when conventional mapping suggested a short
biatrial activation time, 53% (290/550 ms) and
45% (180/400 ms) of the AT1 and AT2 cycle lengths,
respectively. CARTO mapping showed earliest activation in the high anterior and low posterior right
atrium. Successful ablation sites recorded an
electrogram 54 ms (AT1) and 46 ms (AT2) earlier
than the onset of the surface P wave.
Follow-up
After a mean follow-up of 12 G 11 months (range
2e45 months), 2 out of 18 patients (11%) had
recurrence of either the same or a new AA.
Figure 1 Mapping was performed using conventional and CARTO electro-anatomical mapping system in a 44 year-old
woman who had undergone staged repair of Ebstein’s anomaly. The ECG in panel A suggests AT. However,
conventional mapping (in panel B), showed a clockwise reentry along the TA. Panel C, a solid isochronal activation
map of the right atrium, confirms the clockwise typical AFL. Panel D shows an extensive scar (grey coloured) extending
along the superioreanterioreinferior right atrium, forming the posterior boundary of the typical AFL circuit.
Ablation of atrial arrhythmias after open-heart surgery
45
Figure 2 This 44 year-old man underwent patch closure of the septal defect resulting after excision of a left atrial
myxoma. Panel A suggests AFL with positive flutter waves in lead II and negative in lead III. Panel B shows
counterclockwise activation along the TA. The bipole CS 9e10 is not activated in tandem with the Halo catheter and
double potentials, as a result of previous ablation, were recorded on the cavotricuspid isthmus (bipole RF). These
findings suggest a bystander counterclockwise activation along the TA. Panel C confirms reentry around the septal
scar. Activation along the TA, seen in panel D, via two wave fronts that collide in the posterior isthmus at the site of
previously obtained bi-directional block is bystander.
Discussion
Our experience suggests that ablation of AAs after
previous open-heart surgery, performed for valvular or a simple congenital heart disease like an
atrial septal defect, can be performed successfully
(18/19 patients, O90%) and with a low recurrence
rate (2/18 patients, 11%) at 1-year follow-up. In
conformity with Chan et al. [6], we found that,
despite the presence of different atrial scars e
related to atriotomy, venous cannulation or prosthetic patch material, typical AFL occurred frequently (14/19 patients, 72%). Distinctively, this
study included a significant proportion of patients
with previous valve surgery (eight out of 19). Yet,
typical AFL remained a frequent occurrence. This
could, most probably, be related to the right
atriotomy scar. The latter can form an inter-caval
line of block, constituting the posterior boundary
of the typical AFL circuit. More often than not,
typical flutter circuits (along the TA) could be
mapped adequately using conventional multielectrode catheters alone, and successfully ablated. In
addition, peri-scar septal and double-loop reentry
circuits were mapped. CARTO mapping helped to
uncover peri-scar reentry and provided a road-map
for the ablation of an unconventional isthmus. In
our patient cohort, focal ATs were observed in an
isolated case. Recently, ablation studies in patients who had undergone valve repair/replacement [12,18,19], have reported AAs based on
macro-reentrant circuit (right atrial free wall,
between septum and right pulmonary veins and
left atrium) as well as focal ATs. Using conventional [4e6,10,19] or three-dimensional activation
mapping [7e9,11,12,18] different authors, in small
groups of 8e20 patients, have reported acute
success ranging from 80% to 100%. Considering
the preponderance of typical AFL and the possibility of developing AAs based on peri-scar reentry
46
A. Nabar et al.
Figure 3 Atrial septal defect was closed directly in this 44 year-old woman. She had previously undergone His
ablation followed by pacemaker implantation because of recurrent AAs. Panel A suggests AFL with positive flutter
waves in the inferior leads. Conventional mapping, in panel B, might suggest clockwise typical AFL. Panel C and D,
seen together, confirm double-loop reentry as the mechanism of this AA. The first loop is around the right lateral
atriotomy scar and the second is along the TA in a clockwise direction. An unconventional isthmus, between the
atriotomy scar and the TA is shared by both the loops.
after open-heart surgery, it may be appropriate
pre-emptively to ablate the conventional isthmus
intra-operatively and extend the atriotomy incision line to the closest anatomical barrier, by
radiofrequency- or cryo-ablation [20,21].
Intra-cardiac mapping revealed typical AFL
along the TA in three quarters (14/19) of our
patients. Importantly, the ECG had suggested AT
in three of these patients. A similar experience has
been documented by Kasai et al., who mapped
a clockwise AFL, in a patient with surgically
repaired tetralogy of Fallot, in whom the ECG
suggested an AT [22]. In 12 patients, the involvement of the conventional cavotricuspid isthmus
was verified by almost complete mapping of the
flutter circuit along the TA, interruption of the AFL
in the cavotricuspid isthmus during ablation and/or
non-inducibility after obtaining bi-directional isthmus conduction block. In the remaining two patients, in whom the typical AFL had recurred, in
spite of cavotricuspid isthmus ablation in the past,
an unconventional isthmus was successfully targeted under the guidance of the CARTO system.
Recording of low-voltage electrograms on the cavotricuspid isthmus with the consequent difficulty in
selecting ablation sites lead to the choice of an
unconventional isthmus in both these patients. One
patient, who had undergone linear cryoablation
intra-operatively (during septal defect closure),
between the right atriotomy incision and the inferior vena cava, for pre-operatively known AFL,
presented post-operatively with recurrent clockwise typical AFL. In such a case an alternative
ablation strategy could be to extend the atriotomy
to the TA [20].
We used the CARTO system to supplement
conventional mapping, if (1) the ECG morphology
of the clinically documented AA suggested an AT,
(2) conventional mapping was inadequate or inconsistent with reentry along the TA, or (3) an AA
recurred after the ablation of conventional cavotricuspid isthmus in the past. In two patients with
Ablation of atrial arrhythmias after open-heart surgery
47
Figure 4 Mapping and ablation of two focal ATs in a 55 year-old woman post atrial septal defect closure. Panel A
shows the first AT (AT1). Panel B showed bi-directional activation along the crista terminalis (Halo catheter) and
a short biatrial activation time suggestive of a focal mechanism. Panel C shows origin of the focal AT1 in the high
anterior right atrium (orange). Panel D, a bipolar voltage map, shows relation of AT1 to the atriotomy scar.
a reentry circuit localized around the septal scar,
conventional mapping could only document bystander activation along the TA. In case of the
double-loop reentry-based AA, only the activation
loop along the TA was recorded using conventional
techniques. These cases illustrate the inadequacy
of conventional mapping in the setting of peri-scar
reentrant AAs. On the other hand, the CARTO
system allowed complete delineation of the periscar reentry circuit and helped to overlap reliably
the radiofrequency pulses to create a continuous
ablation line across the unconventional isthmus.
When we analyzed the CARTO maps retrospectively, the ablated isthmus was not found to be the
slowest conducting part of the reentry circuit. This
supports that the reentry pathway could be interrupted across any anatomic isthmus that is short
enough and, importantly, provides adequate electrodeetissue contact.
Study limitations
The following limitations of this study should be
acknowledged. Firstly, the likelihood of successful
ablation, judged on the basis of: the ECG morphology of the targeted AA and the possibility of
using the CARTO system, could have led to a preselection of patients referred to us. Secondly,
although O90% of the AA circuit was accurately
delineated using the CARTO system, entrainment
mapping for localizing the reentry circuit and
selecting appropriate ablation sites was not performed. However, the entrainment technique
remains an important tool when studying macroreentrant circuits. Thirdly, due to the presence of
a left-sided prosthetic valve or a previous valve
repair and the hesitation to perform transseptal
puncture in patients with a surgically closed atrial
spetal defect, mapping of the left atrium was not
48
A. Nabar et al.
Figure 5 A second AT (AT2) found in the patient described in Fig. 4. Panel A shows AT2. Once again, panel B, shows
bi-directional activation along the crista terminalis and a short biatrial activation time. These findings suggest a focal
mechanism. Panel C shows origin of the focal AT2 from the low posterior right atrium. Panel D shows relation of AT2 to
the septal scar.
performed. Fourthly, despite regular follow-up
and every attempt to document symptomatic
recurrences, asymptomatic AAs could have been
missed, leading to an underestimation of true
recurrences. Finally, anti-arrhythmic medications
were continued in patients with coexisting atrial
fibrillation. This would be expected to have influenced the evaluation of recurrences during the
follow-up.
References
[1] Saoudi N, Nair M, Abdelaziz A, et al. Electrocardiographic
patterns and results of radiofrequency catheter ablation of
clockwise atrial flutter. J Cardiovasc Electrophysiol 1996;7:
931e42.
[2] Yang Y, Cheng J, Bochoeyer A, et al. Atypical right atrial
flutter patterns. Circulation 2001;103:3092e8.
[3] Kall JG, Rubenstein DS, Kopp DE, et al. Atypical atrial
flutter originates in the right atrial free wall. Circulation
2000;101:270e9.
[4] Kalman JM, van Hare GF, Olgin JE, et al. Ablation of
‘‘incisional’’ reentrant atrial tachycardia complicating
surgery for congenital heart disease: use of entrainment
to define a critical isthmus of conduction. Circulation
1996;93:502e12.
[5] Baker BM, Lindsay BD, Bromberg BI, et al. Catheter ablation
of clinical intraatrial reentrant tachycardias resulting from
previous atrial surgery: localizing and transecting the
critical isthmus. J Am Coll Cardiol 1996;28:411e7.
[6] Chan DP, van Hare GF, Mackall JA, et al. Importance of
atrial flutter isthmus in postoperative intra-atrial reentrant tachycardia. Circulation 2000;102:1283e9.
[7] Iesaka Y, Takahashi A, Goya M, et al. Nonlinear ablation
targeting an isthmus of critically slow conduction detected
by high-density electroanatomical mapping for atypical
atrial flutter. Pacing Clin Electrophysiol 2000;23:1911e5.
[8] Nakagawa H, Shah N, Matsudaira K, et al. Characterization of reentrant circuit in macroreentrant right atrial
Ablation of atrial arrhythmias after open-heart surgery
[9]
[10]
[11]
[12]
[13]
[14]
tachycardia after surgical repair of congenital heart
disease: isolated channels between scars allow ‘‘focal’’
ablation. Circulation 2001;103:699e709.
Delacretaz E, Ganz LI, Soejima K, et al. Multiple atrial reentry circuits in adults with repaired congenital heart
disease: entrainment mapping combined with threedimensional electroanatomic mapping. J Am Coll Cardiol
2001;37:1665e76.
Akar JG, Kok LC, Haines DE, et al. Coexistence of type I
atrial flutter and intra-atrial re-entrant tachycardia in
patients with surgically corrected congenital heart disease. J Am Coll Cardiol 2001;38:377e84.
Love BA, Collins KK, Walsh EP, et al. Electroanatomic
characterization of conduction barriers in sinus/atrially
paced rhythm and association with intra-atrial reentrant
tachycardia circuits following congenital heart disease
surgery. J Cardiovasc Electrophysiol 2001;12:17e25.
Leonelli FM, Tomassoni G, Richey M, et al. Ablation of
incisional atrial tachycardias using a three-dimensional
nonfluoroscopic mapping system. Pacing Clin Electrophysiol 2001;24:1653e9.
Shah D, Jaı̈s P, Takahashi A, et al. Dual-loop intra-atrial
reentry in humans. Circulation 2000;100:631e9.
Saoudi N, Cosio F, Waldo A, et al. Classification of atrial
flutter and regular atrial tachycardia according to
electrophysiologic mechanism and anatomic bases:
a statement from a joint expert group from the Working
Group of Arrhythmias of the European Society of
Cardiology and the North American Society of Pacing
and Electrophysiology. J Cardiovasc Electrophysiol 2001;
12:852e66.
49
[15] Rodriguez LM, Timmermans C, Nabar A, et al. Biatrial
activation in isthmus-dependent atrial flutter. Circulation
2001;104:2545e50.
[16] Smeets JLRM, Ben-Haim SA, Rodriguez LM, et al. New
method for nonfluoroscopic endocardial mapping in
humans: accuracy assessment and first clinical results.
Circulation 1998;97:2426e32.
[17] Nabar A, Rodriguez LM, Timmermans C, et al. Isoproterenol to evaluate resumption of conduction after right
atrial isthmus ablation in type I atrial flutter. Circulation
1999;99:3286e91.
[18] Markowitz SM, Brodman RF, Stein KM, et al. Lesional
tachycardias related to mitral valve surgery. J Am Coll
Cardiol 2002;39:1973e83.
[19] Della Bella P, Fraticelli A, Tondo C, et al. Atypical atrial
flutter: clinical features, electrophysiological characteristics and response to radiofrequency catheter ablation.
Europace 2002;4:241e53.
[20] Uchida F, Kasai A, Fujii E, et al. Radiofrequency catheter
ablation for intra-atrial reentrant tachycardia after surgery of atrial septal defect: use of isopotential mapping
(QMS system) to demonstrate bi-directional complete
block. J Interv Card Electrophysiol 2002;6:59e66.
[21] Henglein D, Cauchemez B, Bloch G. Simultaneous surgical
treatment of atrial septal defect and atrial flutter using
a simple modification of the atrial incision. Cardiol Young
1999;9:197e9.
[22] Kasai A, Anselme F, Cribier A, et al. Postoperative
tachycardia with a P wave identical to that of sinus
rhythm: what is the tachycardia mechanism? J Cardiovasc
Electrophysiol 2000;1:823e4.