Pulmonary vein isolation combined with superior vena
cava isolation for atrial fibrillation ablation: a
prospective randomized study
Xin-Hua Wang, Xu Liu*, Yu-Min Sun, Hai-Feng Shi, Li Zhou, and Jia-Ning Gu
Department of Cardiology, Shanghai Chest Hospital Affiliated to Shanghai Jiaotong University, Shanghai 200030, People’s
Republic of China
Received 21 December 2007; accepted after revision 10 March 2008
Aims Circumferential pulmonary vein isolation (CPVI) is an established strategy for atrial fibrillation
(AF) ablation. Superior vena cava (SVC), by harbouring the majority of non-pulmonary vein
(PV) foci, is the most common non-PV origin for AF. However, it is unknown whether CPVI com-
bined with SVC isolation (SVCI) could improve clinical results and whether SVCI is technically safe and
Methods and results A total of 106 cases (58 males, average age 66.0+8.8 years) with paroxysmal AF
were included for ablation. They were allocated randomly to two groups: CPVI group (n ¼ 54) and
CPVI þ SVCI group (n ¼ 52). All cases underwent the procedure successfully. Pulmonary vein isolation
was achieved in all cases. The procedural time and fluoroscopic time were comparable between the
two groups. The mean ablation time for SVC was 7.8+2.7 min. Superior vena cava isolation was
obtained in 50/52 cases. In the remaining two cases, SVCI was not achieved because of obviating dia-
phragmatic nerve injury. During a mean follow-up of 4+2 months, 12 (22.2%) cases in the CPVI
group and 10 (19.2%) cases in the CPVI þ SVCI group had atrial tachyarrhythmias (ATa) recurrence
(P ¼ 0.70). Nine of 12 cases in the CPVI group and 8/10 cases in the CPVI þ SVCI group underwent rea-
blation (P ¼ 0.86), and PV reconnection occurred in 7/9 cases in the CPVI group and in 8/8 cases in the
CPVI þ SVCI group. All PV reconnection was reisolated by gaps ablation. There was no SVC reconnection
in the CPVI þ SVCI group. In two cases without PV reconnection from the CPVI group, SVC-originated
short run of atrial tachycardia was identified and eliminated by the SVCI. At the end of 12 months of
follow-up, 50 cases (92.6%) in the CPVI group and 49 (94.2%) in the CPVI þ SVC group were free of
ATa recurrence (P ¼ 0.73).
Conclusion In our series of paroxysmal AF patients, empirically adding SVCI to CPVI did not significantly
reduce the AF recurrence after ablation. Superior vena cava isolation may be useful, however, in
selected patients in whom the SVC is identified as a trigger for AF. However, because of the preliminary
property of the study and its relatively small sample size, the impact of SVCI on clinical results should be
evaluated in a large series of patients.
Superior vena cava
Ectopic foci arising from pulmonary veins (PVs) are the pre-
dominant sources for the initiation and maintenance of
atrial fibrillation (AF) in a vast majority of cases.1,2Pulmo-
nary vein isolation has therefore become the main strategy
for treating thisfrustrating arrhythmia.3,4
approach for PV isolation is circumferential PV isolation
(CPVI), which is performed at the PV antrum to encircle PV
foci.5,6However, further studies demonstrate that ectopic
foci also exist in the non-PVs areas in 10–20% of the cases
with paroxysmal AF,7–10such as superior vena cava (SVC),
coronary sinus (CS), inferior vena cava, ligament of Marshall,
and so on. Especially, SVC by harbouring 26–30% of the
non-PV foci becomes the most common non-PV origin for
AF.7This prospective study is carried out to explore
whether SVC isolation (SVCI) is feasible and safe and to
evaluate the effectiveness of adjunctive SVCI for AF therapy.
*Corresponding author. Tel: þ86 21 62821990 60605; fax: þ86 21
E-mail address: firstname.lastname@example.org
Published on behalf of the European Society of Cardiology. All rights reserved. & The Author 2008.
For permissions please email: email@example.com.
Europace (2008) 10, 600–605
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From June 2006 to October 2006, altogether 106 cases (58 males,
average age 66.0+8.8 years) with drug-refractory paroxysmal AF
were included consecutively for catheter ablation. Atrial fibrillation
was refractory to 2.1+1.1 anti-arrhythmic drugs prior to ablation.
By transthoracic echocardiography, the mean left atrium (LA)
diameter was 36.8+2.6 mm (range 29–40 mm) and the mean left
ventricular ejection fraction was 54+8.1% (range 51–60%). Trans-
oesophageal echocardiography was performed to exclude thrombi
in the LA. A total of 22 cases had hypertension, one with coronary
artery disease, one with hypertrophic cardiomyopathy, and seven
with diabetes mellitus.
They were allocated randomly to two groups: CPVI group (n ¼ 54)
and CPVI þ SVCI group (n ¼ 52). Randomization was generated by a
computer after enrolment, but prior to electrophysiological study
and catheter ablation. Cases were blinded to their group assign-
ment. The baseline demographic data of the two groups were
well balanced (Table 1). All cases provided written informed
Prior to ablation, all cases were kept on oral anticoagulation
with warfarin for 1 month, and the drug was withdrawn 3 days
before ablation. Low-molecular-weight heparin was injected sub-
cutaneously twice a day and was withdrawn 12 h prior to ablation.
All anti-arrhythmic drugs except amiodarone were discontinued for
at least five half-lives. The procedure was performed under
conscious sedation with a continuous infusion of propofol. One
decapolar mapping catheter (Biosense Webster, Diamond Bar, CA)
was positioned in the CS via left or right subclavian vein access.
Two L1-type Swartz sheathes (St Jude Medical, Minneapolis, MN)
were advanced in the SVC via right femoral vein and were
advanced into the LA after two successful trans-septal punctures.
Heparin 5000 U was injected via the sheath and followed 1000U/h
to maintain an activated clotting time (ACT) of 300–350 s.
Selective PV venography was performed to identify all PV ostia.
Webster) was positioned at the ostium of each PV to record PV
For cases in the CPVI þ SVCI group, after successful PV isolation
two Swartz sheathes were withdrawn into the right atrium (RA).
Selective SVC venography was performed to identify the RA–SVC
junction. Lasso was positioned at the ostium of the SVC to map
SVC potentials. Surface ECG and bipolar endocardial electrograms
were stored continuously for further analysis. Bipolar signals were
filtered at the range of 300–500 Hz.
Circumferential pulmonary vein isolation
The CPVI procedure was performed under the guidance of the
CARTO system (Biosense Webster), which was described in detail
elsewhere.11In summary, a 3.5 mm saline-irrigated mapping cath-
eter (Navi-Star Thermocool, Biosense Webster) was advanced into
the LA via a Swartz sheath. The geometry of LA was reconstructed,
and each ostium of the PVs was tagged on LA geometry. The ipsilat-
eral left and right PVs were encircled in one lesion line by CPVI.
Radiofrequency (RF) energy was delivered at 438C, 35 W, 0.5 cm
away from the PV ostia at the anterior wall, and it was reduced to
438C, 30 W, 1 cm away from the PV ostia at the posterior wall,
with a saline irrigation speed of 20 mL/min. Each lesion was
ablated continuously until the local potential amplitude decreased
by .80% or RF energy deliveries exceeded 40 s. The endpoint of
CPVI was PV isolation, which was confirmed by Lasso mapping,
showing the disappearance of all PVPs or the dissociation of PVPs
with left atrial activity.
Superior vena cava isolation
After the completion of CPVI, mapping and ablation catheters were
withdrawn back into the RA. The geometry of RA was reconstructed,
and the SVC–RA junction was tagged on the geometry based on the
SVC angiography. Sites at the postero-lateral wall of the SVC with
positive diaphragmatic stimulation by high output pacing (30 mA)
were also tagged on the geometry. In such sites, ablation was
avoided to prevent phrenic nerve injury. Ablation settings were
identical to those in CPVI. Two strategies were applied for SVCI: seg-
mental or circumferential ablation. Segmental ablation was defined
as targeting the earliest RA–SVC conduction when the RA–SVC con-
duction sequence could be discerned in regular atrial rhythm. Cir-
cumferential ablation was defined as connecting ablation lesions
one by one to form a whole lesion line when the RA–SVC conduction
sequence could not be discerned due to an irregular atrial rhythm.
Initial segmental ablation was changed to circumferential ablation
when SVC could not be isolated by ablating .50% of the SVC circum-
ference. Initial circumferential ablation was judged as ‘segmental’
when SVC could be isolated by ablating ,50% of the SVC circumfer-
ence. Superior vena cava isolation was characterized as disappear-
ance of SVC potentials or dissociation of SVC potentials with right
Post-ablation management and follow-up
low-molecular-weight heparin injection for 3–5 days and then
with warfarin for 3 months to maintain an international normalized
ratio range of 2–3. Class III anti-arrhythmic drug with amiodarone,
200–400 mg/day, was administered in all cases for 1 month after
the ablation and was withdrawn 1 month later in cases without AF
recurrence, but was continued otherwise. Surface ECGs were per-
formed and repeated 1 day, 1 week, 1, 2, 3, 6, 9, and 12 months
post-procedure. Monthly telephone inquiry blinded to patient
assignment was made to evaluate the severity of symptoms, and
cases were asked to record ECG when having symptoms indicating
AF. Holter recording was performed for 24 h at 2-month intervals
post-procedure to document any form of atrial arrhythmias. Elec-
trocardiograms and Holters were analysed by reviewers blinded to
The first 1 month after ablation was set as the blanking period,
and the whole follow-up duration was 12 months. After the blanking
cases werekepton anticoagulationtreatmentwith
The baseline demographic data of two groups
(n ¼ 54)
CPVI þ SVCI
(n ¼ 52)
Male, n (%)
AF duration (months)
LA diameter (mm)
Hypertension, n (%)
disease, n (%)
1 (1.9) 0 (0)0.32
1 (1.9)0 (0)0.32
Data are expressed as mean+SD or counts (%). AF, atrial fibrillation;
LA, left atriurn; LVEF, left ventricular ejection fraction.
PV isolation combined with SVCI for AF ablation601
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period, any episode of symptomatic or asymptomatic atrial tachy-
arrhythmias (ATa) with ECG and Holter recording that lasted over
30 s was considered as a recurrence. Reablation was performed at
least 1 month after the initial procedure. Spiral computed tomogra-
phy (CT) was performed at 3 months after the procedure in all cases
to assess the PV or SVC stenosis.
Continuous variables were expressed as mean+SD and categorical
variables as counts or proportions (%). Two-tailed unpaired t-test for
continuous variables of normal distribution or non-parameter test
for inhomogeneity of variance and x2test or Fisher’s exact test
for categorical variables were applied to compare the parameters
between the two groups. A value of P , 0.05 was considered stat-
istically significant. The Kaplan–Meier survival analysis was also
performed to compare the AF-free survival between two groups.
The circumferential pulmonary vein isolation
All cases underwent the procedure successfully. Pulmonary
vein isolation was achieved in all cases. There was no stat-
istically significant difference on the procedural time, left
and right PVs isolation time, and
between the two groups (Table 2).
Superior vena cava isolation
The mean ablation time for SVCI was 7.8+2.7 min, and the
mean numbers of RF energy delivery were 6+2 times.
Superior vena cava was isolated successfully in 50/52
cases. Segmental ablation was performed in 39/50 cases,
SVCI was achieved by ablating 3+1 segments at the
RA–SVC junction, including 54 segments at the septal
aspect of SVC, 41 segments at the posterior wall, 11 seg-
ments at the anterior wall, and 13 segments at the lateral
wall. Circumferential SVC ablation was performed in 11/50
cases, and 9 SVCs were isolated. In the remaining two
cases, SVCI was not achieved due to diaphragmatic stimu-
lation by pacing from the postero-lateral wall of RA.
Follow-up data after initial ablation
During a mean follow-up of 4.6+2.3 months post-ablation,
12 (22.2%) cases in the CPVI group had ATa recurrence,
including AF in 8 cases, left atrial tachycardia in 3 cases,
and AF concomitant with cavo-tricuspid isthmus-dependent
flutter in 1 case. During a mean follow-up of 4.0+2.2
months post-ablation, 10 (19.2%) cases in the CPVI þ SVCI
group had ATa recurrence, including AF in 8 cases and left
atrial tachycardia in 2 cases. Atrial tachyarrhythmias
recurrence proportion between two groups is comparable
(P ¼ 0.70). In both groups, recurrent ATas were refractory
to at least three anti-arrhythmic drugs such as propafenone,
amiodarone, and verapamil.
Results from reablation procedure
Nine (16.7%) of 12 cases in the CPVI group and 8/10 cases
(15.4%) in the CPVI þ SVC group underwent reablation pro-
cedure due to drug-refractory ATa (P ¼ 0.86), including 14
cases with AF (7 cases from the CPVI group and 7 cases
from the CPVI þ SVCI group), 2 cases with left atrial tachy-
cardia (1 case from the CPVI group and the other from the
CPVI þ SVCI group), and 1 case with AF and typical atrial
flutter (from the CPVI group). Pulmonary vein reconnection
occurred in 7/9 cases in the CPVI group and in 8/8 cases
in the CPVI þ SVCI group, which was summarized in
Table 3. During the second ablation procedure, all PV recon-
nection was reisolated by closing gaps along initial ablation
There was no SVC reconnection in 8/8 redo cases in the
CPVI þ SVCI groups.
Superior vena cava-originated extrasystole and short run
of ATa were identified spontaneously or by rapid proximal
CS pacing (cycle length 250–180 ms) in two cases without
PV reconnection in the CPVI group and were eliminated suc-
cessfully by SVCI (Figure 1). Typical atrial flutter was termi-
nated by cavo-tricuspid isthmus ablation in one case. In one
case from the CPVI þ SVCI group, left atrial tachycardia was
caused by the conduction gap along left PV ablation line and
was terminated when closing the gap. In the other case in
The procedural parameters between two groups during
(n ¼ 54)
(n ¼ 52)
LPVs isolation time
RPVs isolation time
SVCI time (min)
Data are expressed as mean+SD or counts (%). LPVs, left-sided pul-
monary veins; RPVs, right-sided pulmonary veins; SVCI, superior vena
Results of circular mapping by Lasso during reablation
(n ¼ 54)
(n ¼ 52)
Cases with ATa
recurrence, n (%)
Reablation cases, n (%)
Proportion of PV
reablation cases, n (%)
Proportion of SVC
12 (22.2)10 (19.2) 0.70
ATa, atrial tachyarrhythmias; LSPV, left superior pulmonary vein; LIPV,
left inferior pulmonary vein; RSPV, right superior pulmonary vein; RIPV,
right inferior pulmonary vein; SVC, superior vena cava.
X.-H. Wang et al.
by guest on June 10, 2015
the CPVI group, left atrial tachycardia was actually mitral
isthmus-dependent flutter and was terminated by mitral
isthmus ablation. During subsequent follow-up, AF still
relapsed in one case in the CPVI group and in one case in
the CPVI þ SVCI group.
Surface electrocardiograms and Holter
documentation during the whole follow-up period
After the first procedure, both groups had 42 cases free of
ATa recurrence. Among them, surface ECGs at scheduled
time were recorded in 39 cases from the CPVI group and in
40 cases from the CPVI þ SVCI group. Holter monitoring
was performed every 2 months in 35 cases from the CPVI
group and in 34 cases from the CPVI þ SVCI group. Atrial
tachyarrhythmias recurred in the remaining 12 cases from
the CPVI group, which was proved by symptomatic ECG
recording in 8 cases, by routine ECG examination in 1
case, and by Holter monitoring in 3 cases. Surface ECGs at
scheduled time and 2-month interval Holter monitoring
were performed in 7/9 reablation cases after the second
procedure; the remaining five cases recorded their ECGs or
Holter occasionally. Atrial tachyarrhythmias recurred in
the remaining 10 cases in the CPVI þ SVCI group, which
was proved by symptomatic ECG recording in 8 cases and
by Holter monitoring in 2 cases. Surface ECGs at scheduled
time and regular Holter monitoring were performed in 7/8
reablation cases, whereas surface ECGs were recorded irre-
gularly in the remaining three cases with ATa recurrence.
Follow-up data after reablation
After the initial ablation procedure, there was no statisti-
cally significant difference on AF-free survival between the
two groups (Figure 2, log rank test, P ¼ 0.75). Cases with
AF and/or ATa recurrence, who underwent second ablation,
were viewed as recurrences. When taking the reablation
cases into consideration, at the end of 12 months of
follow-up, 50 cases (92.6%) in the CPVI group and 49
(94.2%) in the CPVI þ SVC group were free of ATa recurrence
(P ¼ 0.73), including 3 (5.6%) cases in the CPVI group and 2
(3.8%) cases in the CPVI þ SVCI group taking anti-arrhythmic
tachyarrhythmias for both groups. Green line, circumferential
pulmonary vein isolation þ superior vena cava isolation group;
blue line, circumferential pulmonary vein isolation group. Log
rank test, P ¼ 0.75.
Kaplan–Meier curve of freedom from recurrent atrial
in superior vena cava and eliminated by superior vena cava
isolation. Panels A and D: tracings were lead I, V1, Lasso 1–2 to
9–10 within superior vena cava ostium, coronary sinus distal
to proximal, Ablation (ABL) distal to proximal. A, right atrium;
SVCP, superior vena cava potential. Note that in panel A, episode
of atrial tachycardia was initiated by extrasystole from superior
vena cava (superior vena cava potential preceded to A wave).
In panel D, fibrillative rhythm persisted within superior vena
cava, while atrium restored sinus rhythm by superior vena cava
isolation. Panels B and C showed the postero-anterior view and
left anterior oblique view of right atrium and ablation lesion at
the septal and posterior wall of superior vena cava. White dots rep-
resented the ostia of superior vena cava, purple dot represented
the beginning of ablation, red dots represented the ablation
lesions, and green dots represented superior vena cava isolation
Episode of atrial tachycardia triggered by ectopic foci
PV isolation combined with SVCI for AF ablation603
by guest on June 10, 2015
Femoral artery pseudo-aneurysm occurred in one case in the
CPVI group and two cases in the CPVI þ SVC group. Major
stroke was developed in one case with left limb hemiplegia
12 h post-ablation (ACT of 300–340 s was maintained during
the procedure). All complications were treated with conser-
vative therapy. There was no PVor SVC stenosis identified by
CT scan 3 months post-ablation. There was no sinoatrial
node or phrenic nerve injury.
To the best of our knowledge, this is the first randomized
prospective study evaluating SVCI as an adjunctive strategy
for treating paroxysmal AF. The main finding of the study is
that CPVI combined with SVCI contributed little to the
success rate during initial ablation for paroxysmal AF and
that SVCI is necessary to eliminate non-PV-originated AF in
some of redo cases.
The circumferential pulmonary vein isolation
It is established that PVs’ firing is the dominant source for AF
initiation and maintenance. Further studies have demon-
strated that the anisotropic arrangement of myocardial
sleeve around ostia of PVs provides the substrate for
micro-re-entry and fibrillative conduction.12,13The pro-
cedure of CPVI is designed to isolate PVs’ foci as well as to
modify LA substrate and has become the main ablation strat-
egy for AF treatment, especially for the treatment of parox-
ysmal AF. Several investigators have reported a high success
rate of 90–95% for AF elimination after one or two ablation
procedures.5,13In cases with ATa recurrence, PV reconnec-
tion is the main finding during reablation procedures.6Our
study again has replicated the high success rate of CPVI
for paroxysmal AF elimination.
Arrhythmias originating from superior vena cava
The proximal SVC is derived from the embryonic sinus
show that atrial myocardial sleeves extend into SVC for
2–5 cm.16Because the embryological sinus precursor com-
prises all the pacemaker sites, myocardial sleeves in the
SVC harbour ectopic pacing cells that can depolarize by
means of accelerated automaticity17or after depolariza-
tion,18providing the substrate for atrial arrhythmias, such
as atrial tachycardia or AF. Tsai et al.19observed that spon-
taneousbursts of ectopic
SVC-initiated AF in 8 (6%) of 130 cases. Lin et al.7reported
non-PV-originated AF. Lee et al.20reported that AF was ori-
ginated from non-PV foci in 94/293 cases, and 38/94 cases
had AF originating from SVC. A recent study by Arruda
et al.21found that SVC foci were present in 24 (12%) of
190 cases, but their study did not show that SVCI in addition
to PV antrum isolation could improve the success rate of AF
ablation. However, their study is not a randomized and con-
trolled one, and SVCI is only achieved in 82% of the cases;
therefore, it is difficult to evaluate the true contribution
of adjunctive SVCI to the effectiveness of AF ablation. In
our study, only 2 (3.7%) of 54 cases exhibited SVC-originated
AF during reablation. The prevalence of SVC-originated AF in
our study was much lower when compared with the fore-
going studies.7,19–21Probably, it could be explained by the
different induction algorithms applied in each one of the
studies. We observed spontaneous or CS pacing-induced
ectopic beats in our study, whereas in the other studies,
more aggressive induction was applied, such as infusion of
isoproterenol in addition to burst atrial pacing.
Superior vena cava isolation procedure
One autopsy study22of the SVC–RA junction showed that
myocardial sleeves extended from RA to SVC in 38/50 SVCs
and that RA–SVC myocardial connection was discontinuous
most commonly or circumferential in fewer cases, with the
mean thickness of 1.2+1.0 mm and a mean length of
13.7+13.9 mm. Superior vena cava–right atrium connec-
tion is most commonly located at the septum and myocardial
sleeve is thinner at the posterior wall.23On the basis of
these findings, SVCI could be obtained by segmental abla-
tion.24In our study, segmental ablation was performed in
39/50 cases, with the mean procedural time of 7.8+
2.7 min and mean numbers of 3+1 segments of RA–SVC
junction. Circumferential SVCI was performed in only 11/
50 cases. Empirically, SVCI was commenced at the septal
aspect of SVC and subsequently at posterior wall or anterior
wall. We performed high output pacing (30 mA) before
ablating the postero-lateral wall of SVC, and sites with posi-
tive diaphragmatic stimulation were not ablated to mini-
mize the risk of diaphragmatic nerve injury. In two cases,
SVCI was not achieved due to diaphragmatic stimulation by
pacing from the postero-lateral wall of RA. We have not
experienced sinoatrial node injury in this study, although
sinus pause or severe sinus bradycardia has been reported
by several investigators.
Possible explanation of the comparable results
from two groups
It is established that PV reconnection is the main cause for
ATa recurrence after initial CPVI procedure. Ouyang et al.6
reported that PV conduction recovery accounted for .80%
of the ATa recurrence in reablation cases. Even in cases
with prior surgical Maze procedure,25PV reconnection still
was the dominant cause for recurrent ATa. In our study, PV
reconnection occurred in 88% of cases who underwent
second ablation, and by reisolation of all PVs, AF could be
cured in 15/17 cases. Superior vena cava is the main
source for non-PV AF, however, the prevalence of AF with
an SVC origin is much lower than that with a PV origin. In
contrast, our randomized study was a preliminary one and
only 106 cases were included. Due to the low prevalence
of SVC-originated AF and the relatively small sample size,
SVCI contributed insignificantly to the clinical results.
This study has two major limitations: 1. At the time the
study was initiated, little literature was available about
the exact prevalence of AF originating from SVC, although
it was already clear that AF was initiated by PV foci in
.90% of the cases and that AF could be eliminated in 70–
90% of cases by CPVI. Considering the unknown prevalence
of SVC-originated AF, it might be difficult to estimate the
X.-H. Wang et al.
by guest on June 10, 2015
number of patients required to be enrolled. Therefore, this
was a preliminary study and patient enrolment was open.
Owing to the relatively small sample size and the short
follow-up period of the study, we have not observed the
statistically significant difference regarding the success
rate between two groups. The exact role of SVCI on long-
term clinical results should be evaluated in large volume,
long follow-up period studies. 2. The success rate of ablation
might be overestimated as ATa recurrence was mainly
judged upon symptoms. Frequent ECG examination, 24 h
Holter monitoring every 2 months, and monthly telephone
inquiry did not exclude asymptomatic or short episode
In our series of paroxysmal AF patients, adjunctive SVCI does
not significantly improve the success rate of ablation,
although SVCI is necessary for eliminating SVC-originated
AF. Superior vena cava isolation is technically safe and feas-
ible. Owing to the preliminary property of the study and its
relatively small sample size, the impact of SVCI on clinical
results should be evaluated in a large series of patients.
Conflict of interest: none declared.
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by guest on June 10, 2015