World Journal of Cardiovascular Diseases, 2013, 3, 493-498 WJCD
http://dx.doi.org/10.4236/wjcd.2013.38078 Published Online December 2013 (http://www.scirp.org/journal/wjcd/)
Left atrial voltage remodeling after pulmonary venous
isolation with multipolar radiofrequency ablation*
Francesco Laurenzi#, Piergiuseppe De Girolamo, Augusto Pappalardo, Andrea Avella
Department of Cardiology, Cardiac Arrhythmia Center, St. Camillo-Forlanini Hospital, Rome, Italy
Received 30 August 2013; revised 29 September 2013; accepted 18 October 18, 2013
Copyright © 2013 Francesco Laurenzi et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Purpose: Pulmonary vein isolation (PVI) is the ac-
cepted primary endpoint for catheter ablation of
atrial fibrillation (AF). The aim of this study was to
evaluate the level of PVI by PVAC, a multipolar cir-
cular catheter utilizing bipolar/unipolar radiofre-
quency (RF) energy. Methods: Twenty patients with
paroxysmal AF underwent PVAC ablation. PVI was
validated by voltage reduction and pacing tests. Be-
fore and after RF ablation, left atrium (LA) and PV
electroanatomic mapping (EAM) were performed by
EnSite NavX system. Voltage abatement was consid-
ered for potentials < 0.5 mV. RF lesion setting was
compared to the PVs anatomy previously acquired by
a cardiac CT scan. Results: Seventeen patients had
four veins and three had a left common PV. All 77
PVs were isolated by PVAC. After RF, EAM showed
low voltages areas at th e prox ima l PV ostium an d LA.
Segmental voltage abatement slightly distal to the
anatomic PV ostia was achieved in 20/77 (26%) PVs,
more frequently in veins > 24mm: 9/20 (45%) vs
11/57 (19%), p < 0.05. Antral lesions were evident in
38/77 PVs (49%), limited to a part of the antrum in
29/38 (76%) veins, with larger occurrence in round
than in oval PVs ostia: 25/36 (69%) vs 13/41 (32%), p
< 0.001. Conclusions: Electrophysiological PVI with
PVAC is achieved in all the veins with low voltages
areas at the proximal PV ostium. A low voltage
circumferential lesion at the anatomic PV ostia is
more challenging in larger veins. Antral lesions, fre-
quently affecting part of the antra, were more fre-
quent in round PV ostia.
Keywords: Atrial Fibrillation; Pulmonary Vein
Isolation; Multipolar Circular Ablation Catheter;
Electroanatomic Mapping
1. INTRODUCTION
Different strategies are currently used for atrial fibrilla-
tion (AF) catheter ablation, but there is a general con-
sensus on pulmonary vein isolation (PVI) with lesions
proximal to the ostia [1]. A debate is still ongoing about
the amount of left atrium (LA) substrate proximal to the
ostia that should be included in the targeting lesion, as
antra can be involved in initiation and maintenance of the
arrhythmia. The vast majority of AF catheter ablation
procedures rely on point-by-point RF applications and
they need a double transseptal puncture and additional
techniques such as tree-dimensional (3D) mapping sys-
tems or intracardiac echocardiography [1]. To simplify
the procedure, different technologies and tools have been
designed in order to perform a “one-shot” circular lesion
at the PVs ostia. One of these tools is an over-the-wire
circular decapolar catheter (PVAC, Medtronic, Minnea-
polis, MN, USA), capable of mapping and ablating using
alternating bipolar-unipolar radiofrequency (RF) energy.
The feasibility and efficacy of PVAC-based procedures
have been already described with results comparable
with point-by-point strategies, shorter procedure time
and reduced Rx exposure [2-8]. The aim of this study
was to analyse the PVAC lesion setting through a 3D
impedance-based electroanatomic mapping (EAM), to
assess how proximal the lesion extension is with respect
to the PV-LA junction and how it is influenced by ana-
tomical variants.
2. METHODS
2.1. Patients
The study group included patients with symptomatic
paroxysmal AF refractory to antiarrhythmic drugs, who
underwent bipolar-unipolar RF ablation and EAM, be-
*Disclosures: None.
#Corresponding author.

F. Laurenzi et al. / World Journal of Cardiovascular Diseases 3 (2013) 493-498 494
tween January and November 2012. Exclusion criteria
were the presence of a large left atrium (long axis di-
ameter >50 mm), left appendage thrombus, left ventricu-
lar ejection fraction (LVEF) <45%, severe mitral valve
disease, severe renal or pulmonary comorbidity, contra-
indication to oral coagulation and pregnancy.
2.2. Electrophysiological Study and 3D Voltage
Mapping
All patients received oral anticoagulation therapy for at
least 4 weeks up to 3 days before the procedure, then
replaced by a low molecular weight heparin. A computed
tomography (CT) scan of the heart and a transoesophag-
eal echocardiogram were performed within 48 hours be-
fore the procedure. Surface and bipolar electrocardio-
grams (ECGs) were continuously monitored and re-
corded. LA access was gained through a single transsep-
tal puncture to position a steerable 9.5 F sheath (Channel,
Bard EP, Lowell, MA, USA), continuously perfused with
0.9% saline solution. After the transseptal puncture, in-
travenous heparin was administered as a bolus (100
IU/kg) followed by infusion, to achieve and maintain a
target activated clotting time of 350 s.
A 3D reconstruction of the LA and PVs was performed
using the NavX system (EnSite NavX, St Jude Medical,
St Paul, MN, USA). A circular multipolar mapping
catheter (Inquiry A-Focus II, St Jude Medical) was used
for the acquisition of the 3D geometry, which was then
compared side by side to the CT scan-derived anatomy.
PVs ostia were tagged at the intersection of the tangential
lines to PVs and LA walls [9]. A common PV was de-
fined as a unique take-off of contiguous PVs, bifurcating
> 5 mm distal to the PV-LA junction. The proximal bor-
der of the antra has not been standardized yet, but arbi-
trarily we judged the antral extension for lesions occur-
ring > 5 mm from the PVs ostia. PVs ostia were ana-
tomically characterized by measurement of the maxi-
mum and minimum diameter and the relative ratio, de-
fining round shaped ostia for a value ≤ 1.2 and oval
shaped ostia for a ratio > 1.2 [10]. Bipolar voltage maps
were acquired before and after PVs isolation in sinus
rhythm. The following settings were used: interpolation
of 10 mm, internal and external projections of 5 mm.
Normal ECGs were evaluated for voltage recordings
greater than 0.5 mV and were displayed in purple. Volt-
age abatement was considered for potentials ranging
from 0.5 to 0.05 mV displayed in a spectrum of colours
ranging from red to blue, and for signals lower than 0.05
mV marked in grey and conventionally considered as
electrically silent [11]. Off-line quantitative voltage
analysis was performed collecting voltage values of
points mapped at each PV-LA junction and relative
proximal segment of the vein, listed as below: LSPV for
the left superior PV, LIPV for the left inferior PV, LCPV
for the left common PV, RSPV for the right superior PV
and RIPV for the right inferior PV.
2.3. Multipolar Radiofrequency Catheter
Ablation
Ablation of PVs was performed using the PVAC, a de-
capolar circular over-the-wire catheter capable of map-
ping and ablation. The distal circular loop, measuring 25
mm in diameter, can be steered in a bidirectional fashion
and extended in a spiral configuration. The ablation re-
quires a specifically designed RF generator (GENius,
Ablation Frontiers, Medtronic, USA), that allows RF
delivery in various settings of bipolar/unipolar energy
output and, through continuous temperature monitoring
in each electrode, restrict the power output to a maxi-
mum of 10 watts. The location of the decapolar ring was
checked both using fluoroscopy and the 3D PVs-LA re-
construction. RF energy was delivered for 60 s with a
temperature limit of 60˚C, with a bipolar/uniratio of 2:1
when the catheter was in close proximity to the PV an-
trum and 4:1 if the position was more ostial. Cavotricus-
pid isthmus ablation was also performed using an 8-mm
tip RF ablation catheter if a typical right atrial flutter was
observed during the procedure or previously docu-
mented.
2.4. Confirmation of Pulmonary Vein Isolation
Before NavX remapping, PVI was always checked using
the PVAC and then a standard circular multipolar cathe-
ter (Inquiry A-Focus II, St Jude Medical). Electrical de-
connection was assessed by abatement of local potentials
in sinus rhythm and during atrial pacing and by achie-
vement of PVs-LA conduction block. Entry conduction
block was demonstrated by the absence or dissociation of
PVs potentials. Exit block was assessed by pacing at
high output (10 V at 2 ms) from all electrode pairs of the
catheter, positioned in the proximal PVs and at the ostia.
Persistence of PVs isolation was assessed again in all the
PVs at the end of the study. No pharmacological tests
were performed.
2.5. Statistical Analysis
Statistical analysis was performed using SPSS 12.0 for
Windows (SPSS, Inc., Chicago, IL, USA) Continuous
data are expressed as mean values ± standard deviation.
Categorical variables are expressed as a percentage. Dif-
ferences between distributions were compared with a
paired t-test for paired data and unpaired t-test for inde-
pendent values. Differences in proportions were com-
pared with a Fisher’s exact test. A P value < 0.05 was
considered statistically significant.

F. Laurenzi et al. / World Journal of Cardiovascular Diseases 3 (2013) 493-498 495
3. RESULTS
3.1. Patient Characteristics
PVAC lesion setting was evaluated in twenty patients
who underwent alternating bipolar/unipolar RF ablation
and impedance-based EAM. Mean age of the patients
was 59 ± 10 years, 14 were males and 6 females. All the
patients suffered from drug-refractory paroxysmal atrial
fibrillation with a mean CHADS2 Score of 1.2 ± 0.4.
Echocardiographic recordings demonstrated a mean LA
diameter of 41 ± 5 mm and a mean LVEF of 55% ± 6%.
PVs anatomy, ostial size, and shape are summarized in
Table 1. Seventeen patients had 4 veins each (LSPV,
LIPV, RSPV and RIPV) and three patients had three
veins (left common PV, RSPV and RIPV). The PV ostial
shape was classified as oval in 41/77 (53%) and round in
36/77 (47%) veins. Oval ostia had a greater incidence in
left than in right PVs: 24/37 (65%) vs 17/40 (43%), p =
ns. Round ostia were more frequently in right than in left
PVs: 23/40 (57%) vs 13/37 (35%), p = ns.
3.2. Multipolar Radiofrequency Catheter
Ablation
PVAC was able to target and isolate all the 77 PVs, in-
cluding the three LCPVs, independently from size and
shape of the PV ostium. The mean number of duty-cycled
RF applications per patient was 26 ± 9 (range 19 - 44)
with a mean energy delivery time of 24 ± 6 (range 19 -
40) min. The fluoroscopy time was 51 ± 14 min, includ-
ing both the time for PVAC mapping and ablation and
the time due to catheter manipulation for voltage map-
ping. Five patients also underwent cavotricuspid isthmus
ablation.
3.3. 3D Voltage Mapping
The voltage maps were collected before and after PVI
through the acquisition of 343 ± 63 and 371 ± 85 points,
respectively (p = ns). Before ablation all the points
mapped at the PVs antra and in the proximal tubular por-
tion of the veins had a normal voltage (Figures 1(a) and
(b)). After ablation a voltage reduction was evident in all
the PVs and to different extent proximal to their ostia
(Figures 1(c) and (d)), with maps coloured grey (voltage
< 0.05 mV) and red-blue (voltage between 0.05 and 0.5
mV). A quantitative voltage analysis showed a signifi-
cant voltage reduction in all the veins and proximal PVs
ostia (Figure 2): 84% for the LSPV, 88% for the LIPV,
86% for the LCPV, 87% for the RSPV and 81% for the
RIPV (p < 0.05). Mean voltages recorded in the individ-
ual PVs were not significantly different before or after
RF ablation.
The qualitative voltage map analysis of RF lesion set-
ting in respect of ostial shape for each PV is shown in
Table 1. PVs ostia: size and shape.
Maximum
diameter
(mm)
Minimum
diameter
(mm)
Diameter
ratio
Round
PV ost ia
(n)
Oval
PV ost ia
(n)
LSPV 21.2 ± 4.217.0 ± 3.8 1.28 ± 0.3 7 10
LIPV 19.1 ± 2.715.0 ± 2.8 1.26 ± 0.2 6 11
LCPV 30.6 ± 1.522.7 ± 1.1 1.35 ± 0.0 0 3
RSPV 20.2 ± 5.018.8 ± 4.7 1.14 ± 0.1 12 8
RIPV 18.7 ± 3.916.8 ± 3.1 1.19 ± 0.2 11 9
Figure 1. Voltage maps before and after pulmonary vein isola-
tion. Anterior and posterior views of LA voltage maps, before
((a) and (b)) and after ((c) and (d)) PVI by PVAC. Purple col-
our identifies areas of normal voltage (>0.5 mV), colour rang-
ing from red to blue areas with low voltages (<0.5 mV) and
gray colour areas of very low voltage (<0.05 mV). After PVI,
voltage abatement was evident at PV ostia and proximal LA.
The arrow indicates a small area of voltage abatement just dis-
tal to the anatomic right inferior PV ostia.
Figure 3. A reduced segmental voltage abatement was
observed at the anatomic PV ostia in 20/77 (26%) PVs,
with a full low voltage circumferential area slightly distal
to the ostia. This event was more frequent in veins with a
maximum diameter larger than 24 mm: 9/20 (45%) vs
11/57 (19%), p < 0.05, (Ta ble 2). No difference was ob-
served in between left vs right PVs, 12/37(32%) vs 8/40
(20%) p = ns, and round vs oval PV ostia, 11/36 (30%)
vs 9/41 (22%) p = ns.
Ostial RF lesions were detected in 39/77 (51%) veins
and antral lesions in 38/77 PVs (49%). Ostial lesions
were more frequent in oval than in round PV ostia, 28/41
(68%) vs 11/36 (31%), without any difference in left vs
right PVs, 23/37 (62%) vs 16/40 (40%) p = ns, nor in

F. Laurenzi et al. / World Journal of Cardiovascular Diseases 3 (2013) 493-498 496
Figure 2. Voltage before and after pulmonary vein isolation.
Mean voltage values (mV) before (light bars) and after (dark
bars) PVI. LSPV: left superior PV; LIPV: left inferior PV;
LCPV: left common PV; RSPV: right superior PV; RIPV: right
inferior PV.
Figure 3. Lesion setting and ostial shape in each PV. Abbrevia-
tions as in Ta ble 1 . In brackets are indicated the veins with a
segmental voltage abatement slightly distal to the anatomic PV
ostia.
veins with a diameter larger than 24 mm, 23/37 (62%) vs
16/40 (40%), p = ns.
Antral lesions had a greater occurrence in round than
in oval PV ostia: 25/36 (69%) vs 13/41(32%), p < 0.001.
No any difference was observed in left vs right PVs,
14/37(38%) vs 24/40 (60%) p = ns, nor in veins larger
than 24 mm, 8/20 (40%) vs 30/57 (53%), p = ns.
Antral extension of RF lesions were evident in the
whole antra in 9/38 veins and limited to a part of the PV
antrum in 29/38 (76%) PVs: the posterior wall in 24 and
the anterior wall in 5 PV antra.
4. DISCUSSION
Our data confirm the results of a previous study [12]
about the ability of PVAC to perform PVI at the proximal
ostium, even in more challenging anatomical variants as
three left common PVs, in which ostial lesions were car-
ried out by insertion of the guide in different venous
branches.
After RF ablation, the impedance-based EAM showed
a significant reduction in the bipolar voltage at the PV
ostia, proximal to the tubular part of the PVs. However
about one in four veins, frequently the larger ones, show-
ed a segment of reduced voltage abatement at the anat-
omic PV ostium with slightly distal low voltage encir-
cling. Far-field signal recording, particularly frequent in
left-sided veins because of their proximity to the left
atrial appendage, was ruled out by remapping with stand-
ard catheters and pacing maneuvers. On the other hand, a
partial sided placement of the PVAC at the ostia may be
the cause of the distal segmental voltage abatement:
before RF erogation in any new catheter position, the
location of the PVAC was displayed on the 3D mapping
system, but a tiny displacement may have occurred as a
consequence of the pressure exerted during RF delivery
in order to achieve a better contact and the target tem-
perature.
In our experience antral extension of RF lesions was
achieved more frequently in round veins, as counter-
clockwise catheter rotation allows a wider sweep more
easily around the circumference of round PV ostia. More
often the antra were partially affected by RF lesions,
probably as a result of different causes. Firstly, the PV’s
short axis is oriented approximately in the anteroposte-
rior direction. Secondly, the transseptal access naturally
directs the catheter posteriorly into the LA, so that its
circular ending is obliquely oriented with the anterior
part located at the PV ostia and the posterior part more
atrial. Finally, a greater antral contact was more easily
achieved posteriorly by bending and rotating the catheter
around the ostial circumference. On the contrary, the
small distance between the left PVs and the LA append-
age [10] can limit the placement of the circular catheter
in the anterior LA walls more than that of a single-tip
catheter.
In our study the fluoroscopic and procedural mean
times were longer than those previously described [2-8],
because the procedure required an additional EAM and
probably a different learning curve, since the mean num-
ber of RF applications was similar.
The PVAC is an over-the-wire catheter designed to be
managed under fluoroscopic control, with more detailed
definition of the PV-LA junction usually achieved by
angiography. A small risk of PV stenosis is described in
some studies [13,14]. In our experience the 3D-geometry
reconstruction eased the positioning of the PVAC at the
ostia and the parallel orientation to the PV’s walls, but
was not useful for catheter navigation as it is conditioned
by the over-the-wire design. Regarding the voltage map-
ing, the low voltage signals recorded are not accurate
enough to indicate PVI, which in fact was validated with
electrophysiological entry and exit blocks. Moreover,
maps can be affected by far-field potentials, particularly
from the left atrial appendage, thus requiring accurate
characteristics analysis and pacing maneuvers. As the
PVAC-EAM combined strategy is more expensive and

F. Laurenzi et al. / World Journal of Cardiovascular Diseases 3 (2013) 493-498 497
Table 2. Qualitative voltage map analysis.
Segmental low voltage area distal to the a natomic PV ostia n. 20/77 p value
Left vs right PVs 12/37 (32%) vs 8/40 (20%) 0.30
Round vs oval PV ostia 11/36 (30%) vs 9/41 (22%) 0.44
PV diameter > 24 vs < 24 mm 9/20 (45%) vs 11/57 (19%) 0.037
Ostial lesions n . 39/77
Left vs right PVs 23/37 (62%) vs 16/40 (40%) 0.069
Round vs oval PV ostia 11/36 (31%) vs 28/41 (68%) 0.001
PV diameter > 24 vs < 24 mm 12/20 (60%) vs 27/57 (47%) 0.44
Antral lesion n. 38/77
Left vs right PVs 14/37 (38%) vs 24/40 (60%) 0.069
Round vs oval PV ostia 25/36 (69%) vs 13/41(32%) 0.001
PV diameter > 24 vs < 24 mm 8/20 (40%) vs 30/57 (53%) 0.44
time consuming, other techniques such as angiography or
3D CT/MRI cardiac scan reconstruction are to be pre-
ferred for PV-LA junction definition.
This study outlines the significance of two factors in
order to choose the more effective ablation tool: the
knowledge of the individual anatomy that is useful to
perform a right positioning of the circular mapping-ab-
lation catheter, and the a priori preference of a wide en-
circling PVI strategy that is easier to achieve with a sin-
gle-point RF catheter.
Limitations
This study analyzed the primary lesion setting after
PVAC ablation in a relatively small but representative
group of patients, referred for paroxysmal AF catheter
ablation.
PVI was assessed by standard electrophysiological
criteria as there is no absolute agreement between myo-
cardial viability and low voltages and also because the
maps can be affected by LA far-field potentials. As re-
peated mapping procedures were not performed, the
study does not clarify to what extent the ablation lesions
remain permanent.
5. CONCLUSION
Electrical PVI with PVAC is not affected by the size and
shape of the PV ostium and results in low voltage areas
mainly at the PV ostium and proximal LA. However,
voltage reduction in the whole circumference of the
anatomic PV ostia is more challenging in larger veins,
and antral lesions are variable in occurrence and exten-
sion, so knowledge of the individual anatomy of the PVs
and LA can be useful in order to choose the more effec-
tive ablation tool.
6. ACKNOWLEDGEMENTS
The authors wish to thank Simona Benedetti, Roberta Annibali and
Sergio Orsini for technical assistance and data collection and Tiziana
De Santo for statistics.
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