Europace (2008) 10, 190–196
doi:10.1093/europace/eum296
Prevalence of typical atrial flutter with reentry circuit
posterior to the superior vena cava
Use of entrainment at the atrial roof
Philippe Maury*, Alexandre Duparc, Aurelien Hebrard, Mohamed El Bayomy, and Marc Delay
Fédération de Cardiologie, University Hospital Rangueil, 31059 Toulouse Cedex 09, France
Received 26 October 2007; accepted after revision 12 December 2007; online publish-ahead-of-print 18 January 2008
KEYWORDS
Typical atrial flutter;
Lower loop reentry;
Upper turn around;
Entrainment
Aims Upper turn-around of the reentry circuit in typical atrial flutter (AF) is classically described to be
located in front of the superior vena cava (SVC), but circuits posterior to the SVC as well as lower loop
reentry (LLR) involving only the lower part of the right atrium have been described. However, true
prevalence of such AF circuits remains unknown.
Methods and results Fifty consecutive patients (46 men, 68 + 9 years old) undergoing radiofrequency
(RF) ablation of typical counter-clockwise AF were prospectively investigated. Prior to RF deliverance,
AF was entrained by pacing 10 ms shorter than the AF cycle length (AFCL). Post-pacing interval (PPI) at
the cavotricuspid isthmus (CTI) and at the atrial roof (AR)—between SVC and the high tricuspid annulus—
were determined. AR was considered to be part of the AF circuit when local PPI–AFCL was 20 or 30 ms
or, in case of long PPI at the CTI isthmus, if difference between AR-PPI and CT-PPI was 10 ms. In 47
patients, CTI-PPI–AFCL was 30 ms (94%). Among them, AR-PPI–AFCL was .30 ms in 12 cases (25%).
In the remaining three patients, AR-PPI–AFCL did not exceed CTI-PPI–AFCL by more than 10 ms. In 42
patients, CTI-PPI–AFCL was 20 ms (84%). Among them, AR-PPI–AFCL was .20 ms in 16 cases (39%).
In the remaining eight patients, AR-PPI–AFCL was more than 10 ms longer than CTI-PPI–AFCL in only
one instance. Taken together, AR PPI was .20 or .30 ms longer than AFCL or .10 ms longer than
CTI PPI when prolonged in 17 (34%) and 12 patients (24%), respectively.
Conclusion In around a quarter to one-third of patients referred for RF ablation of typical AF, the
atrial roof is not part of the circuit, thus they may present a ‘posterior’ variant of the typical
counter-clockwise AF reentry circuit.
Introduction
Electrophysiological studies in man have provided significant
evidence suggesting that the mechanism of typical atrial
flutter (AF) is based on a large macro-reentry located in
the right atrium.1–3 In its typical form, AF consists of a
counter-clockwise right atrial activation with an atrial rate
of 240–340 bpm and is classically characterized on electrocardiogram (ECG) by the biphasic and predominantly negative saw-tooth pattern in the inferior leads.1,2,4 Apparent
constant and monotonous ECG pattern of typical AF in man
is usually perceived as a marker of uniformity in the atrial
activation and in the reentry circuit.5 During typical
AF, the counter-clockwise reentrant wavefront surrounds
* Corresponding author. Tel: þ33 5 61 32 20 94; fax: þ33 5 61 32 22 46.
E-mail address: [email protected]
a central obstacle formed by the inferior vena cava and
the still poorly delimited adjacent areas of functional
block3,4 with an activation proceeding superiorly along the
inter-atrial septum and then inferiorly along the lateral
right atrial free wall1 before getting through the cavotricuspid isthmus (CTI).2,3
If the CTI is the well-known, lower turning point of the
circuit and therefore represents the obligatory target for
successful radiofrequency (RF) ablation, precise delineation
of the upper turn-around has been somewhat disregarded,
even if it is commonly proposed to be located in front of
the superior vena cava (SVC). In fact, circuits posterior to
the SVC6 and lower loop reentry (LLR)7 involving only the
inferior part of the right atrium have been described, but
the prevalence of such circuit variants remains unknown.
Entrainment is widely used to prove the reentrant nature
of arrhythmias and to further delineate the involved reentry
Published on behalf of the European Society of Cardiology. All rights reserved. & The Author 2008.
For permissions please email: [email protected].
Prevalence of typical atrial flutter with reentry circuit
circuit.8 The analysis of post-pacing interval (PPI) after
sudden cessation of pacing with transient entrainment provides valuable clues about the location of the pacing site
relative to the reentry circuit. A difference 20–30 ms
between PPI and the tachycardia cycle length usually leads
to the assumption that the pacing site is close to or included
in the atrial circuit.9–11
The aim of this study was to prospectively evaluate the
prevalence of patients presenting with counter-clockwise
typical AF with common ECG features who share, in fact, a
more posterior and/or lower superior turn-around of the
reentry circuit. For that purpose, entrainment at the atrial
roof (AR) was used.
Methods
Fifty consecutive patients presenting with typical counter-clockwise
AF and undergoing RF catheter ablation were prospectively
included. Only patients with typical AF displaying the classical negative saw-tooth ECG pattern in inferior leads were included.
One standard quadripolar electrode-catheter and one RF roving
catheter were inserted percutaneously via the right femoral vein.
The quadripolar catheter was positioned under fluoroscopic guidance along the tricuspid annulus in the lower portion of the right
atrial lateral wall. Descending atrial activation attesting for
counter-clockwise right atrial activation was present in each case.
The 8 mm-tip (Stinger, Bard, Lowell, MA, USA) or 4 mm-tip (Thermocool, Biosense Webster, Inc., Diamond Bar, CA, USA) steerable RF
catheter with 2-5-2 mm inter-electrode spacing was positioned at
the CTI and at the AR for pacing manoeuvres. Filtered and amplified
bipolar intracardiac electrograms were recorded on a Cardiolab
system (Prucka Eng., Houston, TX, USA). Measurements were
made at a speed of 200 mm/s using callipers on screen. Regularity
of AF cycle length was checked at baseline. Differences of 10 ms
or more between successive and non-successive cycles were considered as an exclusion criterion.
Transient entrainment of AF was performed before the first RF
application. Pacing was performed using the distal dipole of the
RF catheter once at the CTI [6 o’clock in the left anterior oblique
(LAO) view and local electrograms during the flat part of the F
wave in inferior leads] and once again at the right atrial roof (12
o’clock in LAO view). AR was reached in each patient after the RF
catheter was placed in the SVC, then curved before drawing it
back till the tip falls in the atrium. The catheter tip was then maintained in close contact with the AR using a gentle push. Adequate
positioning of the catheter was attested by a satisfactory fluoroscopic location in both right anterior oblique (RAO) and LAO views
and a good contact confirmed by stable and sharp local
Figure 1 308 right oblique anterior (left panel) and 608 left oblique
anterior (right panel) views during contrast right atrial angiography,
showing the atrial appendage, the right atrial roof and the superior
vena cava (SVC). The ablation catheter is positioned against the
atrial roof for entrainment manoeuvres.
191
electrograms. An example of positioning the RF catheter at the AR
is shown in Figure 1.
Electrical stimulation was carried out using a programmable
orthorhythmic stimulator (Biotronik UHS 20) with 1 ms pulse duration and sufficient output to allow constant capture, at a fixed
rate of 10 ms faster than the AF cycle length, in order to avoid
decremental conduction inside the circuit and artificially prolonged
PPI.12,13 Entrainment was confirmed in each patient by verifying
that the atrial rate on the quadripolar catheter was transiently
accelerated to the pacing rate. PPI was measured after sudden cessation of pacing between the last spike artefact and the onset of the
next local atrial depolarized event on the RF catheter.
Differences between AF cycle length and PPI at the CTI (CTI-PPI–
AFCL) and at the AR (AR-PPI–AFCL) were then calculated and compared in each patient (Figure 2). Pacing locations showing differences between local PPI and AF cycle length .20 ms11 or
.30 ms9,10 were considered to be outside the circuit. Typical AF
being present in each case, CTI PPI was supposed to match the AF
cycle length in all patients, however, despite the fact that the
flutter was typical, e.g. CTI-dependent, occasional cases displayed
long PPI at the CTI. In these cases, AR was suspected not to
belong to the circuit if AR PPI was .10 ms longer than CTI PPI.
Statistical analysis
Results are expressed as means + SD (range). Comparisons between
groups were performed using Fisher’s exact test for categorical data
and with Student’s unpaired t-test or non-parametric Mann–Whitney
test for numerical variables when appropriate. Numerical data
during entrainment at the AR and at the CTI was compared using
paired t-test. A P-value ,0.05 was considered statistically
significant.
Results
Clinical characteristics of the 50 patients are depicted in
Table 1. None had undergone a prior RF procedure for AF.
Mean AF cycle length was 250 + 29 ms (210–325). RF ablation
was successful in all patients with the termination of AF
during RF application at the CTI and achievement of complete
bidirectional CTI block in each. Complete bidirectional block
was confirmed by checking clockwise activation during low
lateral right atrial pacing and counter-clockwise activation
during coronary sinus ostium pacing, together with the differential pacing technique.14 This technique has been proved to
have good long-term predictive value in our experience.15
Local capture and transient entrainment at the CTI and at
the AR could be achieved in each patient. Entrainment
neither stopped AF or changed AF pattern or cycle length,
nor induced atrial fibrillation or atypical AF in any patient.
Mean CTI-PPI–AFCL was 9 + 12 ms (0–45) and mean
AR-PPI–AFCL was 20 + 23 ms (0–90) (P ¼ 0.005).
CTI-PPI–AFCL was 30 ms in 47 patients (94%). Among
these 47 patients, AR-PPI–AFCL was .30 ms in 12 cases
(25%) (57 + 15 ms, 40–90). In the remaining three patients,
AR-PPI–AFCL (25 + 15 ms, 10–40 ms) did not exceed
CTI-PPI–AFCL (40 + 5 ms, 35–5 ms) by more than 10 ms.
CTI-PPI–AFCL was 20 ms in 42 patients (84%). Among
these 42 patients, AR-PPI–AFCL was .20 ms in 16 cases
(39%) (47 + 18 ms, 25–90). In the remaining eight patients,
AR-PPI–AFCL (21 + 18 ms, 0–50 ms) was more than 10 ms
longer than CTI-PPI–AFCL (32 + 7 ms, 25–45 ms) in only
one instance.
Taken together, PPI measured at the atrial roof was
.20 ms longer than AF cycle length (or .10 ms longer
than CTI PPI when this was prolonged) in 17 patients (34%)
192
P. Maury et al.
Figure 2 Intracardiac tracings during entrainment at the cavo-tricuspid isthmus (CTI) and at the atrial roof (AR). Atrial flutter cycle length
(AFCL) is 235 ms. After transient entrainment at a pacing cycle of 225 ms, post-pacing interval (PPI) is 25 ms longer than AFCL at the CTI and is
65 ms longer than AFCL at the AR. See text for explanation. RA dt, md and px, quadripolar lead positioned at the right atrial lateral wall; RF
dt, distal tip of the ablation catheter.
Table 1 Clinical variables of patient population
Gender
Age
Underlying heart disease
Ischaemic
Valvular
Hypertensive
Dilated cardiomyopathy
Cor pulmonale
Pericardial disease
Mixed
Normal LVEF
Mean LVEF (if altered)
Previous atrial fibrillation
Previous cardiac surgery
Anti-arrhythmic druga
Acute amiodarone
Chronic amiodarone
Sotalol
LVEF, left ventricular ejection fraction.
a
At the time of the procedure.
46 males (92%)
68 + 9 years (40–83)
38 patients (76%)
14 patients
8 patients
3 patients
5 patients
3 patients
2 patients
3 patients
34 patients (68%)
0.36 + 0.11 (0.2–0.5)
21 patients (42%)
15 patients (30%)
34 patients (68%)
17 patients
16 patients
1 patient
and was .30 ms longer than AF cycle length (or .10 ms
longer than CTI PPI when this was prolonged) in 12 patients
(24%). This implies that in around a quarter to one-third of
patients referred for RF ablation of typical AF with
common ECG features, the atrial roof is not part of the
circuit, and thus they may present a ‘posterior’ variant of
the typical counter-clockwise AF reentry circuit.
Electrophysiological findings in common and ‘posterior’
forms of AF are listed in Table 2. Neither age, nor gender,
a preserved ejection fraction, the presence or type of
underlying heart disease, a history of previous atrial fibrillation or of cardiac surgery, the recurrence rate or the concomitant administration of any type of anti-arrhythmic drugs
were significantly correlated with either common or ‘posterior’ form of AF, whether defined by cut-off values of 20
or 30 ms. Only in the subgroup of patients with altered ejection fraction, patients presenting with common AF presented with higher ejection fractions compared with the
posterior form (as defined by a cut-off value of 30 ms), but
the statistical difference was of borderline value (0.38 +
0.11 vs. 0.27 + 0.05, P ¼ 0.07) and this was not observed
if the posterior form was defined by a cut-off value of 20 ms.
Prevalence of typical atrial flutter with reentry circuit
193
Table 2 Comparisons of the electrophysiological results
between common vs. posterior form of atrial flutter (AF)
(see text for explanation)
Common AF
Posterior AF
P
(n ¼ 38)
248 + 29
10 + 13
9 + 12
11 (29%)
(n ¼ 12)
255 + 33
5+9
57 + 14
5 (41%)
NS
NS
,0.0001
NS
(n ¼ 33)
248 + 27
10 + 13
6 + 10
10 (30%)
(n ¼ 17)
253 + 34
7+9
48 + 18
5 (29%)
NS
NS
,0.0001
NS
(Cut-off value 30 ms)
AFCL (ms)
CTI-PPI–AFCL (ms)
AR-PPI–AFCL (ms)
Chronic amiodarone
(Cut-off value 20 ms)
AFCL (ms)
CTI-PPI–AFCL (ms)
AR-PPI–AFCL (ms)
Chronic amiodarone
AF recurred in two patients (4%) over a follow-up of 13 + 6
months. Both patients underwent a second successful
procedure.
Discussion
In this study, using straightforward entrainment technique
at the right atrial roof, we found that a quarter to one-third
of patients referred for RF ablation of typical AF with
common ECG features do not have the upper limb of the
reentry circuit directly crossing the atrial roof between
the anterior root of the SVC and the high posterior aspect
of the tricuspid annulus. Although true determination of
the path behind the posterior side of the SVC was not performed, the activation front should necessarily cross the
posterior wall and the crista terminalis at an undetermined
level in these cases.
Historically, delineation of the anatomical reentry circuit
involved in human typical counter-clockwise AF described a
circuit rotating between the tricuspid annulus and both vena
cava,12 but lacked precision concerning the tissues involved
between the upper septum and the high right atrial lateral
wall. The upper turn-around of the activation wavefront
was suspected to be located anterior to the SVC opening
in the seminal work by Puech and colleagues, although no
recording in the atrial roof had been performed.1 Multiple
intra-cardiac recordings have lately led to schemes also displaying an activation crossing in front of the SVC.16,17
However, no entrainment was performed in all those
studies.
Entrainment mapping at the AR was only performed once
before: in 13 patients, pacing from sites close to the tricuspid annulus and therefore anterior to the SVC displayed
exact PPI, so that activation across the crista terminalis
did not occur in any of these cases.13 In another study
including 13 patients,18 entrainment of typical counterclockwise AF from the high posterior right atrium never
changed the activation sequence between high septum, AR
and the high anterior wall: it was concluded that activation
occurs consistently cranial to the SVC, and that a complete
posterolateral line of block is constant between both venae
cavae.18 Using entrainment mapping at various sites precisely determined by intracardiac echocardiography, Olgin
et al. showed an activation travelling down along the
trabeculated anterior right atrium, and therefore anterior
to the crista terminalis. Their data suggesting that the
crista terminalis represents a fixed line of block,19 the reentrant wavefront has to cross anterior to the SVC.
However, using intracardiac echocardiography in 20
patients with counter-clockwise typical AF,20 a line of functional block was found postero-medially in an inverted ‘V’
shape around which the reentry rotated, suggesting an
upper limit to this line of block. However, precise relationship with the SVC was not determined.20 The authors postulated that typical AF was composed of two competing loops:
a first one around the tricuspid annulus and a shorter one
around the IVC, the crista terminalis permeability or a
short line of postero-medial block making the latter loop
dominant.20 The ascendancy of faster LLR on ‘typical’
counter-clockwise AF has been also explained in this
manner.7 On the other hand, because of fast circumferential
conduction in the longitudinal direction along the continuous epicardial circular fibres,21 peri-tricuspid activation
might be favoured compared with a posterior/lower loop
with slow transverse conduction across the crista
terminalis.22
Non-fluoroscopic three-dimensional mapping allows
tracing more precisely the path of the reentrant movement.
According to Shah et al., the activation front was shown to
be crossing the anterior root of the SVC in 14 of 17 patients
with typical counter-clockwise AF and fusing around the SVC
in three cases (17%) with a posterior propagation slightly
earlier than that of the anterior limb.6 In another study,
the activation wavefront was shown to propagate both
anterior and posterior to the SVC in all seven patients with
counter-clockwise AF before fusing and proceeding down
the anterior right atrial wall.23 Of note, there was no case
of activation occurring only posterior to the SVC and, once
again, entrainment mapping was not performed in these
studies.6,23
Posterior by-passing of the AR by transverse activation
across the higher part of the crista terminalis is a plausible
phenomenon, since medial to lateral conduction across
this structure during pacing was observed in most patients
presenting with typical AF.24,25 Transverse crista terminalis
conduction was detectable in 58% of patients with typical
AF when paced from the coronary sinus after achievement
of complete bidirectional CTI block.26 In this study, earliest
breakthrough along the anterior tricuspid annulus occurred
in two-thirds of patients in the low lateral part and in a
more superior area in the remaining cases, or were multiple
in a few cases.26
In 1999, Cheng et al. first described the lower loop reentry
as a new mechanism for fast typical AF due to a shorter
reentry circuit. In their study of 29 patients with typical
counter-clockwise AF, they were able to induce (3 of 28)
or document spontaneous (3 of 26) faster AF with early
breakthrough at the low lateral right atrium, with collision
of counter-clockwise and clockwise activations occurring
at a higher level on the lateral wall.7 However, documented
episodes in this study were often short-lasting and selflimited. Counter-clockwise LLR with variable (and sometimes high) wavefront breaks have been retrospectively
found in 19 of 328 (6%) consecutive patients referred for
RF ablation of CTI-dependent AF.27,28 Most of the episodes
investigated in this study were sustained, stable and
194
P. Maury et al.
Figure 3 Examples of 12-lead electrocardiogram of posterior form of typical atrial flutter (see text for details).
occurred spontaneously, suggesting they were probably
more clinically relevant.27,28
Because of a similar efficiency of CTI ablation in curing
both LLR and typical counter-clockwise AF and because of
similar ECG patterns, diagnosis of this variant of typical AF
is usually missed if not cautiously investigated, thus the
prevalence of such a mechanism is probably underestimated. Even if prospective evaluation of the real prevalence
of LLR circuits is still lacking, our results reveal that the AR
is probably not included into the AF circuit in a quarter to
one-third of cases of typical counter-clockwise AF. The ‘posterior’ form of typical AF as described here differs from the
LLR, however, because low lateral right atrial activation on
the quadripolar catheter was descending in all cases probably because of a much higher breakthrough, while activation would be ascending, diverging or colliding in case of
LLR. Finally, a double loop-reentry consisting of a peritricuspid loop together with a LLR could be potentially
present in every patient, as already postulated,20 the final
effective re-entrant front being dictated by the competing
revolution times of each loop. Additional studies with high
density mapping are mandatory to assess this issue.
This study was not designed to evaluate the surface ECG
characteristics of the posterior variant of typical AF. No
ECG feature has been shown to correlate with circuits
anterior or posterior to the SVC opening.6 ECG features of
lower loop reentry are known to be similar to those of
typical counter-clockwise AF except for the loss of positive
terminal deflection in inferior leads, attributed to the
change in activation of the lateral right atrial free wall.7
Changes in atrial activation and surface ECG would be
minor if the breakthrough is high,12 however more pronounced differences can be observed according to other
authors if breakthrough occurs at a higher level, leading to
a wavefront collision occurring over the high lateral or
septal right atrial areas.28 When looking back at the
surface ECG in each of the 12 cases with the ‘posterior’
form of typical AF as defined by a cut-off value of 30 ms,
we found a lack of terminal positive deflection in inferior
leads in four instances, and biphasic þ/2 pattern in V1 in
five cases (examples are shown in Figure 3).
Clinical implications
Alternative sites for RF ablation in typical AF have been
already proposed, for example between the high crista terminalis and the tricuspid annulus.13 Ablation at the AR would
represent an optional solution when abnormalities prevent
access to the CTI from the IVC, such as occluded IVC, IVC
filter29 or complete azygos continuation of the IVC.30 Usefulness of this solution is however questionable in view of our
results, because of conduction across the crista terminalis
in a significant proportion of cases. Moreover, there are
sleeves of activation extending up into the SVC.31 Finally,
linear ablation at the AR with complete local conduction
block could reveal or leave a posterior loop alone.
Prevalence of typical atrial flutter with reentry circuit
Limitations of the study
This study has several limitations, particularly concerning
entrainment. Entrainment from CTI or AR was performed
only once, so that we could not conclude about the reproducibility of our results. No analysis of other entrainment criteria on ECG and/or intracardiac activation has been made
during CTI or AR pacing; however, conclusions based on PPI
are usually robust and can hardly be misleading. Our conclusions based on PPI analysis are only valid for the sites
where pacing has been made, but not necessarily for other
parts of the AR. No entrainment was performed at the
high posterior wall just above the posterior aspect of the
SVC opening, and this could have proved posterior by-pass
during AF. The existence of a bystander posterior wave
front or of a double loop cannot be excluded when AR PPI
is close to the AFCL.
Multipolar electrode catheter was not routinely used, thus
true activation at the high lateral right atrium was not
determined. Even if low lateral right atrial activation was
descending in all cases, higher levels of transverse conduction could not be detectable in this study.
Half of our patients were on amiodarone at the time of
the procedure. This could have altered some of our conclusions. First, prolonged PPI after pacing in the reentry
circuit in patients under amiodarone has been observed.32
This could explain most of the cases with long AR PPI in
our study since 11 of such 14 cases were treated by amiodarone, but if it were the case, CTI PPI would then also
be prolonged32 and this was observed in only two patients.
Secondly, amiodarone is a drug known to decrease AF
cycle length32,33 and was in fact prescribed in 17 patients
with AFCL .260 ms, a rather low atrial rate for typical AF.
This could have introduced another inclusion bias,
however, patients in this study were consecutively and prospectively included, so that our results seem to be applicable to the clinical practice. Furthermore, there was no
significant difference in the proportion of posterior form of
AF whether chronic amiodarone was prescribed or not
(Table 2).
Patients presenting with reverse-typical clockwise AF
were not included in this study, so that the proportion of
cases not including the atrial roof in these circuits is
unknown. LLR may however be a predominant mechanism
during clockwise AF, accounting for most of the 12 cases
studied by Zhang et al.34 True prevalence of such forms in
clockwise AF deserves further studies.
Because angiographic delineation of the AR was not performed in most of our patients, it is therefore possible
that entrainment at the right appendage could have happened in some instances. This could have lead to long PPI
and overestimation of ‘posterior’ AF prevalence, since
atrial appendage is not involved in the AF circuit.13
However, this should concern only a minority of cases
because of the methodology used.
Pacing at 10 or even 20 mA output was sometimes used to
allow constant capture. This could have led to a distant
capture of areas closer to the circuit even when pacing
outside the reentrant path because of an increased size of
the virtual electrode.35 However, this phenomenon is
rather limited when pacing in a bipolar configuration35 and
probably not clinically relevant13,34 because of the distance
between AR and the posterior high right atrium.
195
Finally, patients with recurrent typical counter-clockwise
AF after previous RF ablation were not included in this study.
It has been shown that LLR can occur after partial and
incomplete CTI ablation because of cycle length prolongation.12 Further studies are necessary to evaluate the
prevalence of LLR or posterior form of typical AF occurring
in the setting of previous CTI ablation.
Conflict of interest: none declared.
References
1. Puech P, Latour H, Grolleau R. Le flutter et ses limites. Arch Mal Cœur
1970;1:116–44.
2. Waldo AL. Treatment of atrial flutter. Heart 2000;84:227–32.
3. Cosio FG, Lopez-Gil M, Goicolea A, Arribas F, Barroso JL. Radio-frequency
ablation of the inferior vena cava-tricuspid valve isthmus in common
atrial flutter. Am J Cardiol 1993;71:705–9.
4. Waldo AL, Mackall JA, Biblo LA. Mechanisms and medical management of
patients with atrial flutter. Cardiol Clin 1997;15:661–76.
5. Cosio FG, Arribas F. Role of conduction disturbances in atrial arrhythmias.
In:Patrick Attuel, Philippe Coumel, Janse MJ, eds. The Atrium in Health
and Disease. Mount Kisco, New York, Futura Publishing Company, Inc.;
1989. p. 133–57.
6. Shah DC, Jaı̈s P, Haı̈ssaguerre M, Chouairi S, Takahashi A, Hocini M et al.
Three dimensional mapping of the common trial flutter circuit in the right
atrium. Circulation 1997;96:3904–12.
7. Cheng J, Cabeen WR, Scheinman MM. Right atrial flutter due to lower
loop reentry. Circulation 1999;99:1700–5.
8. Saoudi N, Anselme F, Poty H, Cribier A, Castellanos A. Entrainment of
supraventricular tachycardias: a review. Pacing Clin Electrophysiol
1998;21:2105–25.
9. Morton JB, Sanders P, Deen V, Vohra JK, Kalman JM. Sensitivity and specificity of concealed entrainment for the identification of a critical isthmus
in the atrium: relationship to rate, anatomic location and antidromic
penetration. J Am Coll Cardiol 2002;39:896–906.
10. Triedman JK, Alexander ME, Berul CI, Bevilaqua LM, Walsh EP. Electroanatomic mapping of entrainment and exit zones in patients with repaired
congenital heart disease and intra-atrial re-entrant tachycardia. Circulation 2001;103:2060–5.
11. Saoudi N, Cosio F, Waldo A, Chen SA, Iesaka Y, Lesh M et al. A classification of atrial flutter and regular atrial tachycardia according to electrophysiological mechanisms and anatomical bases. Eur Heart J 2001;
22:1162–82.
12. Cosio FG, Martin-Penato A, Pastor A, Nunez A, Goicolea A. Atypical
flutter: a review. Pacing Clin Electrophysiol 2003;26:2157–69.
13. Kalman JM, Olgin JE, Saxon LA, Fisher WG, Lee RJ, Lesh MD. Activation
and entrainment mapping defines the tricuspid annulus as the anterior
barrier in typical atrial flutter. Circulation 1996;94:398–406.
14. Shah DC, Haı̈ssaguerre M, Takahashi A, Jaı̈s P, Hocini M, Clementy J.
Differential pacing for distinguishing block from persistent conduction
through an ablation line. Circulation 2000;102:1517–22.
15. Maury P, Raczka F, Gaty D, Duparc A, Celse D, Couderc P et al. Radiofrequency ablation of atrial flutter. Long-term results and predictive
value of cavo-tricuspid isthmus bidirectional block as determined by a
simplified technique. Cardiology 2008;110:17–28.
16. Chauvin M, Brechenmacher C, Voegtlin JR. Application de la cartographie
endocavitaire à l’étude du flutter auriculaire. Arch Mal Cœur 1982;9:
1020–30.
17. Poty H, Saoudi N, Nair M, Anselme F, Letac B. Radiofrequency catheter
ablation of atrial flutter. Further insights into the various types of
isthmus block: application to ablation during sinus rhythm. Circulation
1996;94:3204–13.
18. Arribas F, Lopez-Gil A, Cosio FG, Nunez A. The upper link of human
common atrial flutter circuit: definition by multiple endocardial recordings during entrainment. Pacing Clin Electrophysiol 1997;20:2924–9.
19. Olgin JE, Kalman JM, Fitzpatrick AP, Lesh MD. Role of right atrial endocardial structures as barriers to conduction during human type I atrial
flutter. Activation and entrainment mapping guided by intracardiac echocardiography. Circulation 1995;92:1839–48.
20. Friedman PA, Luria D, Fenton AM, Munger TM, Jahangir A, Shen WK et al.
Global right atrial mapping of human atrial flutter: the presence of posteromedial (sinus venosus region) functional block and double potentials.
Circulation 2000;101:1568–77.
196
21. Racker DK, Ursell PC, Hoffman BF. Anatomy of the tricuspid annulus. Circumferential myofibers as the structural basis for atrial flutter in a canine
model. Circulation 1991;84:841–51.
22. Schumacher B, Jung W, Schmidt H, Fischenbeck C, Lewalter T,
Hagendorff A et al. Transverse conduction capabilities of the crista terminalis in patients with atrial flutter and atrial fibrillation. J Am Coll
Cardiol 1999;34:363–73.
23. Rodriguez LM, Timmermans C, Nabar A, Hofstra L, Wellens HJJ. Biatrial
activation in isthmus-dependent atrial flutter. Circulation 2001;104:
2545–50.
24. Anselme F, Savouré A, Ouali S, Cribier A, Saoudi N. Transcristal conduction during isthmus ablation of typical atrial flutter: influence on
success criteria. J Cardiovasc Electrophysiol 2004;15:184–9.
25. Arenal A, Almendral J, Alday JM, Villacastin J, Ormaetxe JM, Sande JL
et al. Rate-dependent conduction block of the crista terminalis in
patients with typical atrial flutter. Circulation 1999;99:2771–8.
26. Yang Y, Wahba GM, Liu T, Mangat I, Keung EC, Ursell PC et al. Site specificity of transverse crista terminalis conduction in patients with atrial
flutter. Pacing Clin Electrophysiol 2005;28:34–43.
27. Bochoeyer A, Yang Y, Cheng J, Lee RJ, Keung EC, Marrouche NF et al.
Surface electrocardiographic characteristics of right and left atrial
flutter. Circulation 2003;108:60–6.
P. Maury et al.
28. Yang Y, Cheng J, Bochoeyer A, Hamdan MH, Kowal RC, Page R et al. Atypical right atrial flutter patterns. Circulation 2001;103:3092–8.
29. Haman L, Parizek P, Maly R, Vojacek J. Cavotricuspid isthmus catheter
ablation across an inferior vena cava filter. Pacing Clin Electrophysiol
2006;29:331–3.
30. Guenther J, Marrouche N, Ruef J. Ablation of atrial flutter by the femoral
approach in the absence of inferior vena cava. Europace 2007;9:1073–4.
31. Shah DC. Atrial flutter: contemporary electrophysiology and catheter
ablation. Pacing Clin Electrophysiol 1999;22:344–59.
32. Fatemi M, Mansourati J, Rosu R, Blanc JJ. Value of entrainment mapping
in determining the isthmus-dependent nature of atrial flutter in the presence of amiodarone. J Cardiovasc Electrophysiol 2004;15:1409–15.
33. Maury P, Zimmermann M. Effect of chronic amiodarone therapy on the
excitable gap during typical human atrial flutter. J Cardiovasc Electrophysiol 2004;15:1416–23.
34. Zhang S, Younis G, Hariharan R, Ho J, Yang Y, Ip J et al. Lower loop
reentry as a mechanism of clockwise right atrial flutter. Circulation
2004;109:1630–5.
35. Wikswo JP Jr, Wisialowski TA, Altemeier WA, Balser JR, Kopelman HA,
Roden DM. Virtual cathode effects during stimulation of cardiac
muscle. Two-dimensional in vivo experiments. Circ Res 1991;68:513–30.