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\begin{document}

\title{Intracardiac echocardiography-guided transseptal puncture for flouroless
catheter ablation of left-sided tachycardias}



\author[1]{David Žižek}%
\author[1]{Bor Antolič}%
\author[2]{Tine Prolič Kalinšek}%
\author[1]{Jernej Štublar}%
\author[1]{Nina Kajdič}%
\author[3]{Matija Jelenc}%
\author[2]{Matevž Jan}%
\affil[1]{University Medical Centre Ljubljana Division of Internal Medicine}%
\affil[2]{University Medical Centre Ljubljana}%
\affil[3]{University Medical Center Ljubljana}%


\vspace{-1em}



  
  \date{June 17, 2024}


\begingroup
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\selectlanguage{english}
\begin{abstract}
Introduction Integration of intracardiac echocardiography (ICE) and 3D
electroanatomic mapping (EAM) system allows transseptal punctures (TSP)
without the use of fluoroscopy. Compared to fluoroscopy, ICE provides
better visualization of the anatomy relevant to TSP and early
recognition of complications. The aim was to evaluate efficacy and
safety of entirely ICE- guided TSPs in patients who underwent fluoroless
catheter ablation of left-sided tachycardias. Methods and results
Consecutive 524 adult and pediatric patients referred to our institution
from July 2014 to December 2019 were analyzed. Patients with cardiac
implantable electronic devices (CIEDs) were also included. All
procedures were performed with ICE-guided TSP combined with 3D EAM.
Adverse events fol-lowing TSP and within 30 days of the procedure were
analyzed. Altogether 949 TSPs (363 double punctures, 76.5\%) were
performed in 586 fluoroless ablation procedures: 451 (77\%) were
ablation of atrial fibrillation or atypical flutter, 75 (12.8\%) of
left-sided accessory pathway, 33 (5.6\%) of ventricu-lar tachycardia,
and 27 (4.6\%) of focal atrial tachycardia. Forty-six (7.8\%) procedures
were performed in pediatric population and 36 procedures (6.1\%) in
patients with CIED. Only 2 TSPs were unsuc-cessful (2/949, 0.2\%).
Overall procedural complication rate was 1.9\% (11/586 procedures).
There was only 1 TSP related pericardial tamponade (2/949, 0.2\%). In
CIED patients there was 1 lead dislo-cation following TSP. Conclusion
Entirely ICE-guided TSPs for different left-sided tachycardias can be
safely and effectively performed in adult and pediatric population
without the use of fluoroscopy. However, caution is advised in CIED
patients due to possible lead dislocation risk.%
\end{abstract}%



\sloppy


\textbf{Intracardiac echocardiography-guided transseptal puncture for
flouroless catheter ablation of left-sided tachycardias}

\textbf{Brief title:} Fluoroless transseptal puncture

David \selectlanguage{polish}Ž\selectlanguage{english}i\selectlanguage{polish}ž\selectlanguage{english}ek, MD, PhD\textsuperscript{1}, Bor Antoli\selectlanguage{polish}č, \selectlanguage{english}MD,
PhD\textsuperscript{1}, Tine Proli\selectlanguage{polish}č \selectlanguage{english}Kalin\selectlanguage{polish}š\selectlanguage{english}ek, MD\textsuperscript{2},
Jernej \selectlanguage{polish}Š\selectlanguage{english}tublar, MSc\textsuperscript{1}, Nina Kajdi\selectlanguage{polish}č,
\selectlanguage{english}MD\textsuperscript{1}, Matija Jelenc, MD, PhD\textsuperscript{2}, Matev\selectlanguage{polish}ž
\selectlanguage{english}Jan, MD\textsuperscript{2}

\textsuperscript{1} Cardiology Department, University Medical Centre
Ljubljana, Ljubljana, Slovenia

\textsuperscript{2} Cardiovascular Surgery Department, University
Medical Centre Ljubljana, Ljubljana, Slovenia

Correspondence: David \selectlanguage{polish}Ž\selectlanguage{english}i\selectlanguage{polish}ž\selectlanguage{english}ek, MD, PhD. Department of Cardiology,
University Medical Centre Ljubljana, Zalo\selectlanguage{polish}š\selectlanguage{english}ka 7, 1000 Ljubljana,
Slovenia. Tel: + 386 1 522 85 34; fax: +386 1 522 28 28; e-mail:
david.zizek@kclj.si. ORCID: https://orcid.org/0000-0001-5029-3989

\textbf{Conflict of interest:} David \selectlanguage{polish}Ž\selectlanguage{english}i\selectlanguage{polish}ž\selectlanguage{english}ek received consulting/advisory
board support from Medtronic and Boston Scientific. Bor Antoli\selectlanguage{polish}č \selectlanguage{english}and
Matev\selectlanguage{polish}ž \selectlanguage{english}Jan received proctorship fees from Biosense Webster. All other
authors have no relationships relevant to the contents of this paper to
disclose.

\textbf{Funding:} the study did not receive any financial support.

\textbf{Structured Abstract}

\textbf{Introduction}

Integration of intracardiac echocardiography (ICE) and 3D
electroanatomic mapping (EAM) system allows transseptal punctures (TSP)
without the use of fluoroscopy. Compared to fluoroscopy, ICE provides
better visualization of the anatomy relevant to TSP and early
recognition of complications. The aim was to evaluate efficacy and
safety of entirely ICE- guided TSPs in patients who underwent fluoroless
catheter ablation of left-sided tachycardias.

\textbf{Methods and results}

Consecutive 524 adult and pediatric patients referred to our institution
from July 2014 to December 2019 were analyzed. Patients with cardiac
implantable electronic devices (CIEDs) were also included. All
procedures were performed with ICE-guided TSP combined with 3D EAM.
Adverse events following TSP and within 30 days of the procedure were
analyzed. Altogether 949 TSPs (363 double punctures, 76.5\%) were
performed in 586 fluoroless ablation procedures: 451 (77\%) were
ablation of atrial fibrillation or atypical flutter, 75 (12.8\%) of
left-sided accessory pathway, 33 (5.6\%) of ventricular tachycardia, and
27 (4.6\%) of focal atrial tachycardia. Forty-six (7.8\%) procedures
were performed in pediatric population and 36 procedures (6.1\%) in
patients with CIED. Only 2 TSPs were unsuccessful (2/949, 0.2\%).
Overall procedural complication rate was 1.9\% (11/586 procedures).
There was only 1 TSP related pericardial tamponade (2/949, 0.2\%). In
CIED patients there was 1 lead dislocation following TSP.

\textbf{Conclusion}

Entirely ICE-guided TSPs for different left-sided tachycardias can be
safely and effectively performed in adult and pediatric population
without the use of fluoroscopy. However, caution is advised in CIED
patients due to possible lead dislocation risk.

\textbf{Key words:} transseptal puncture, intracardiac echocardiography,
3-dimensional systems, fluoroless, left-sided tachycardias

\textbf{Unstructured Abstract}

Compared to fluoroscopy, intracardiac echocardiography (ICE) provides
better anatomical visualization and early recognition of complications
related to transseptal puncture (TSP). A total of 949 ICE-guided TSPs
(586 fluoroless left-sided arrhythmia procedures) performed in adult and
pediatric patients were retrospectively analyzed. With a 99.8\% success
rate and only 1 transseptal access related pericardial tamponade
(0.2\%), entirely ICE-guided TSP can be successfully and safely
performed in fluoroless CA of left-sided arrhythmias. As 1 lead
dislocation was recorded following TSP caution is advised in patients
with intracardiac electronic devices.

\textbf{Abbreviations}

3D = three-dimensional

AF = atrial fibrillation

AP = accessory pathway

AT = atrial tachycardia

AVNRT = atrioventricular nodal reentry tachycardia

CA = catheter ablation

CIED = cardiac implantable electronic device

EAM = electro-anatomic mapping

IAS = interatrial septum

ICE = intracardiac echocardiography

PTA = percutaneous angioplasty

RF = radio-frequency

SD = standard deviation

SVT = supra-ventricular tachycardia

TEE = transesophageal echocardiography

TSP = transseptal puncture

VT = ventricular tachycardia

\textbf{Introduction}

The transseptal puncture (TSP) is a routine procedure in
electrophysiology to perform catheter ablation (CA) of atrial
fibrillation (AF) and other left-sided arrhythmias including ventricular
tachycardias (VT) (1).

Although fluoroscopic guidance to perform TSP is still the gold standard
in clinical practice (2,3), ultrasound-based techniques including
transesophageal echocardiography (TEE) and intracardiac echocardiography
(ICE) have been adopted to provide additional imaging of different
anatomical structures relevant to TSP. Utilization of both imaging
techniques could shorten fluoroscopy exposure, increase safety and
success rate of electrophysiological procedures, especially in
challenging cases (4-6). Furthermore, improvement of image quality and
integration with three-dimensional 3D electro-anatomic mapping (EAM)
systems enabled ICE to become an invaluable tool for safe and effective
guidance of catheters and needle direction during TSP without the use of
fluoroscopy (7). While the fundamental technique of performing ICE-based
TSP in flouroless approach remains the same, available data to support
routine use of this technique is relatively scarce. In addition, there
are some considerations regarding safety and efficacy, especially in the
pediatric population and in patients with cardiac implantable electronic
devices (CIEDs) (8,9).

The purpose of this single-center retrospective study was to evaluate
efficacy and safety of consecutive entirely ICE-guided TSPs in patients
undergoing fluoroless CA for different left-sided tachycardias.
Pediatric population and patients with CIEDs were also included in the
analysis.

\textbf{Methods}

The study complies with the Declaration of Helsinki. The study and
fluoroless CA procedures were approved by The National Medical Ethics
Committee (Komisija za medicinsko etiko Republike Slovenije) and the
institutional review board. All patients (or their parents in case of
pediatric patients) gave written informed consent before ablation
procedures were performed.

\textbf{Patient population}

In this retrospective study we included 524 consecutive adult and
pediatric patients who were referred to our institution from July 2014
to December 2019 requiring TSP for CA of left-sided arrhythmias.
Fluoroless approach in our center was gradually implemented for
different CA procedures. Consequently, patients with left-sided
tachycardias were included in this retrospective study at different
points in time with consecutive TSPs thereafter: left-sided
supra-ventricular tachycardias (SVTs) since July 2014, AF since March
2015 and left-sided VT since March 2017.

Left sided focal atrial tachycardia (AT), left-sided accessory pathway
(AP) mediated tachycardia, atrioventricular nodal reentry tachycardia
(AVNRT), or left-sided VT typically received single transseptal access.
Patients with AF and left-sided atypical atrial flutters typically
received double TSPs, except patients undergoing hybrid (combined
surgical and catheter ablation) procedure for AF which received single
transseptal access. Typically, the radio-frequency (RF) needle technique
was used in difficult TSP cases. Pediatric patients and patients with
CIEDs were also included. Each CIED was tested for proper function
before and after the procedure to ensure no change in pacing and sensing
parameters occurred. Lead visualization during procedures was entirely
performed with ICE without fluoroscopy.

\textbf{Procedural workflow}

Procedures were generally performed in conscious sedation, except in
pediatric patients (\textless{} 14 years) and patients undergoing hybrid
procedure for AF who received general anesthesia. Bilateral femoral vein
punctures were performed to access the heart. All procedures were
performed with 3D EAM system (NavX; Abbott, IL, USA or Carto\selectlanguage{ngerman}®; Biosense
Webster, CA, USA) and ICE (Acunav\selectlanguage{english}; Biosense Webster, CA, USA). All
parts of the procedures were performed completely without the use of
fluoroscopy, including mapping and ablation.

All patients received a full therapeutic dose of heparin before TSP and
majority of AF patients had an uninterrupted anticoagulation strategy.
Activated clotting time was regularly checked after having achieved
transseptal access with a target of at least 300 seconds. The SR0\selectlanguage{english} or
SL1\selectlanguage{english} long sheaths with dilators (Abbott, IL, USA) and HeartSpan(r)
transseptal needle (71cm, 50\% curve, 21 Gauge; MeritMedical, Utah, USA)
were typically used for TSP. In case of the ``RF needle'' technique a
full metal BRK\selectlanguage{english} transseptal needle (71 cm, 50\% curve, 18 Gauge; Abbott,
IL, USA) was used.

\textbf{Intracardiac echocardiography-guided transseptal puncture}

First, the ICE probe was advanced from the femoral vein into the right
atrium. ICE probe was then further advanced into the right ventricle and
the right ventricular outflow tract to visualize left atrial appendage
and exclude the presence of possible thrombotic masses. Subsequent
entirely ICE-guided workflow for achieving transseptal access is shown
in Figure 1.

ICE was used to visualize the position of the guide wire and later the
position and the course of the long sheath / dilator / transseptal
needle assembly during the pull-down maneuver. Amid this maneuver the
aortic root, pulmonary veins and the interatrial septum were used as
landmarks which were repeatedly visualized with a slight clockwise or
counterclockwise rotation of the ICE probe. Postero-inferior part of the
oval fossa just opposite to the posterior aspect of the left pulmonary
vein antrum was the target for landing the dilator tip in preparation
for the TSP. ICE was also used to confirm the presence, orientation and
exact location of the transseptal needle tip, the dilator tip, the long
sheath tip and the guide wire in the left atrial cavity during different
stages of transseptal puncture.

In addition, ICE was used to monitor the pericardial space during the
procedure in a case of chest discomfort or arterial pressure drop. This
was achieved with advancing the ICE probe into the right ventricle and
rotating it clockwise until left ventricular cavity and surrounding
pericardial space were visualized.

\textbf{Radio-frequency needle technique}

In difficult cases with initially unsuccessful TSP due to stiff or
thickened IAS the RF needle technique was utilized. The main advantage
of this technique is that significant mechanical force is not needed for
successful and safe TSP (10). In short, after the long sheath / dilator
/ transseptal needle assembly was positioned at the optimal location on
the IAS (panel D, Figure 1), the transseptal needle was pushed against
the oval fossa. During consistent pressure of the needle and under
uninterrupted ICE guidance the RF energy was applied to the shaft of the
metal needle with the ablation catheter. Due to the expected rise of the
impedance the high impedance cutoff on the RF generator was set to the
maximum value. The RF energy of 20W was generally applied for 5 -10
seconds until the tip of the needle was visualized in the LA cavity
(panel E, Figure 1). The subsequent steps of TSP were as previously
described in Figure 1.

\textbf{Transeptal puncture in patients with intracardiac devices}

When TSP was performed in a presence of a CIED its interrogation with
testing lead sensing, pacing threshold and impedance was performed
before and after the procedure. Also, lead position was repeatedly
visualized with ICE during the pull-down maneuver of the long
sheath/dilator/needle assembly to avoid possible entanglement and lead
dislocation. X-ray fluoroscopy was not used for TSP in patients with
CIEDs.

\textbf{Adverse events}

Major adverse events were defined as those causing termination of the
procedure, prolonged hospital stay, long-term disability, requiring
surgical intervention, CIED lead repositioning or bleeding requiring
transfusion. In general, we focused on adverse events that could be
directly attributed to TSP. Pericardial effusions occurring after
completion of ablation procedures were not attributed to TSP.
Periprocedural adverse events were monitored within 30-days of the
ablation procedure. Cardiac perforation was suspected when the symptoms
such as substernal discomfort, shoulder discomfort, abdominal
discomfort, nausea, or clinical signs of hemodynamic instability were
detected and pericardial effusion was confirmed with ICE or
transthoracic echocardiogram. Pericardial effusion that necessitated
intervention was defined as cardiac tamponade.

\textbf{Statistical analysis}

The baseline characteristics were reported as mean and standard
deviation (SD) for numeric measures and counts and percentages for
categorical measures. Successful TSPs and complications were reported as
percentages. Reporting of cases with unsuccessful TSP, use of RF needle
technique and similar deviations were only descriptive since the number
of events was low.

\textbf{Results}

Altogether 949 TSPs were performed during 586 procedures in 524
patients. Patient characteristics are shown in Table 1. The majority of
procedures were performed for AF or atypical atrial flutter. However,
TSPs in other left-sided arrhythmias were also assessed: VT (5.6\%), AT
(4.6\%), AP mediated tachycardia and AVNRT with left sided location of
the slow pathway (12.8\%). Procedural characteristics are shown in Table
2. 57 patients had two (46 for AF, 3 for atypical atrial flutter, 5 for
AP mediated tachycardia, 2 for focal AT, 1 for VT) and 5 patients had
three procedures (3 for AF, 1 for and 1 for AP mediated tachycardia).
Double TSPs were performed in majority of procedures for AF or atypical
atrial flutter (350/451, 78\%) and in a minority of procedures for focal
atrial tachycardia (8/27, 30\%) and VT (5/33, 15\%). There were no
double TSPs in patients treated for AP mediated tachycardia and AVNRT.

Only few procedures (41/586, 7\%) were performed under general
anesthesia; in pediatric patients who were under 14 years of age (22
procedures) and in patients undergoing hybrid ablation for persistent
atrial fibrillation (19 procedures).

Only two TSPs were unsuccessful (2/949, 0.2\%), both in patients with
AF. In one patient with prior surgical removal of myxoma the operator
was unable to puncture through the stiff IAS. The transseptal access was
later successfully performed using RF needle technique. In the second
unsuccessful TSP the presence of inferior vena cava filter precluded the
femoral venous access. Subsequently right transjugular access was
attempted but the operator was unable to insert a steerable or
non-steerable long sheath into the left atrial cavity due to acute angle
between the superior vena cava (SVC) and the IAS. Two procedures in
patients with AF were aborted due to a visible mobile structure on the
wire/long sheath/dilator assembly (2/586, 0.3\%). In all cases, mapping
and ablation parts of the procedure after successful TSP were performed
completely without the use of fluoroscopy.

\textbf{Transseptal puncture in pediatric patients}

Forty-six (7.8\%) procedures with single TSPs were performed in
pediatric population. Of those, 41 procedures were performed for AP
mediated tachycardia, 4 for focal AT and 1 for fascicular VT. Seven
(7/46, 15\%) were performed in patients weighing less than 30 kg. The
youngest patient was 4 years old and weighted 17 kg. Mean age and weight
of pediatric patients were 12.5 +- 4 years and 51.8 +- 19.5 kg,
respectively.

\textbf{Transseptal puncture in patients with intracardiac devices}

Thirty-six procedures (6.1\%) with 51 TSPs were performed in the
presence of CIED (28 TSPs in single chamber devices, 21 TSPs in dual
chamber devices and 2 TSPs in cardiac resynchronization device). One
patient (1/51 punctures, 2\%) with a dual chamber device had procedure
related dislocation of the ventricular lead that occurred at the time of
achieving single transseptal access for VT ablation. There were no other
lead dislocations and no changes in lead parameters according to pre and
post-procedural device interrogations.

\textbf{RF needle technique}

Four difficult single TSPs (4/949, 0.4\%) were successfully performed
with the RF needle technique: 2 punctures in consecutive procedures in a
patient with prior surgery of atrial myxoma, 1 TSP in a patient after
previous AF ablation procedure, and 1 puncture where initial ICE
evaluation revealed hypertrophied IAS. In the patient after previous AF
ablation procedure, the percutaneous angioplasty (PTA) balloon was used
to dilate the septal puncture site which enabled left atrial access with
the long sheath. This was the only case where 7 seconds of low dose
fluoroscopy (2 frames per second) was used during PTA balloon
positioning and inflation. There were no adverse events in patients
where RF needle technique was used.

\textbf{Adverse events}

Overall procedural complication rate was 1.9\% (11/586 procedures). We
registered 6 pericardial effusions that occurred after the completion of
CA procedures and resolved spontaneously, causing only prolonged
hospital stay. These pericardial effusions could not be attributed to
TSP. Also, there were two femoral artery pseudoaneurysms requiring
surgical intervention and one transient phrenic nerve palsy causing
disability during the six-month recovery period. Detailed information on
adverse events is provided in Table 3.

Importantly, adverse event rate that could be unequivocally attributed
to the transseptal access was only 0.3\% (3/949). Of note, one
transseptal access related adverse event was CIED ventricular lead
dislocation. Lead repositioning was performed during the same
hospitalization. There was only 1 pericardial tamponade requiring
intervention recorded immediately after double TSP was performed (2/949,
0.2\%). Since this was a double transseptal puncture and it was not
clear which of the punctures resulted in tamponade, both were registered
as adverse events. The cause for tamponade in this case was probably
inadvertent puncture of the opposite left atrial wall during advancement
of the transseptal needle in the presence of a small left atrium and a
floppy interatrial septum.

\textbf{Discussion}

Our single-center retrospective study showed high success rate and very
low complication rate of entirely ICE-guided TSPs for fluoroless CA
treatment of left-sided tachycardias. Safety was also maintained in the
pediatric population and, to a lesser degree, in patients with CIEDs.

\textbf{Intracardiac echocardiography-guided transseptal puncture}

To facilitate TSP, ICE or TEE are used as additional imaging tools when
difficult anatomy is encountered during fluoroscopy-guided TSP (5,6).
Although cost-effectiveness in routine practice compared to TEE is
unclear, ICE has additional advantages of not requiring a second
operator, general anesthesia and provides better acoustic window.
Furthermore, integration of ICE with 3D EAM systems enabled CA
procedures of various arrhythmias without the use of fluoroscopy (7,11).
There are several reasons to adopt radiation-reducing strategies in CA
procedures. The ALARA (as low as reasonably achievable) principle is
based on the hypothesis that there is no threshold below which ionizing
radiation is free from harmful effects for the operator and the patient
(12). Furthermore, patient radiation risk from CA procedures may highly
exceed radiation risk from common radiological procedures (13).

There is limited data regarding feasibility and safety of ICE-guided TSP
in CA of left-sided arrhythmias without the use of fluoroscopy.
Recently, Baykaner al. (9) demonstrated efficacy and safety of zero
fluoroscopy TSPs in 646 AF patients using multiple procedural approaches
at 5 high-volume centers. Our results extend these finding with a more
simplified fluoroless transseptal approach which was also used in a
pediatric population, in patients with CIEDs, and in various left-sided
arrhythmias not only AF.

\textbf{Transseptal puncture in pediatric patients}

In our analysis, all 46 pediatric patients with left-sided AP mediated
tachycardia had successful TSPs without any complications. Present
findings are in line with Clark et al. (14) who presented transseptal
procedures in 9 pediatric patients without the use of fluoroscopy.
Compared to the latter study, we also included smaller children weighing
less than 30 kg where ICE was particularly useful to control the needle
direction and monitor the space between the bulging IAS and LA wall with
very small maneuvering space.

\textbf{Transseptal puncture in patients with intracardiac devices}

Available data in the literature on fluoroless TSP in the presence of
CIEDs is scarce. Fluoroless approach for transseptal access is usually
avoided or fluoroscopy is used at least to some extent during the
procedure (9). In our study, 51 TSPs in 36 CIED patients were entirely
ICE-guided with good visualization of the leads. However, we recorded
one dislocation of the ventricular lead during TSP in VT ablation
procedure. Lead dislocation due to entanglement with catheter system was
intraoperatively detected with ICE. Thus, in patients with CIED caution
is advised when attempting entirely ICE-guided TSP. Brief use of
fluoroscopy for CIED lead visualization during long sheath / dilator/
transseptal needle assembly and during different stages of the CA
procedure is probably reasonable if entanglement is suspected.

\textbf{Difficult transseptal puncture}

Anticipation and definition of difficult TSP is challenging even with
additional preprocedural cardiac imaging. Previous AF ablation
procedures and prior surgical or percutaneous interventions in the IAS
area increase the risk for difficult TSP (5, 15, 16). Although punctures
with the aid of the RF needle technique that could be considered
difficult in our study were low, we experienced no safety or efficacy
issues with fluoroless ICE-guided approach. There were two patients in
whom difficult TSP could be anticipated: one had previous transseptal
access for AF ablation and second had prior surgical procedure on IAS.
On the other hand, we can speculate that direct visualization of soft
tissue structures and anatomical variations with ICE provides better
reassurance of optimal puncture site compared to fluoroscopy and reduces
the number of potentially difficult TSPs. Consequently, difficult cases
could be reduced to just cases with stiff or thickened IAS / oval fossa
where RF needle technique can be utilized to increase safety and
efficacy (10).

\textbf{Adverse events}

Overall procedural complication rate in our study was low (1.9\%) and
adverse events unequivocally attributable to TSP were even lower. In the
setting of uninterrupted anticoagulation, there are several mechanisms
of cardiac perforation during CA procedure including mechanical trauma
of thin LA walls, coronary sinus perforation and steam pops during RF
energy delivery. However, with various technological improvements of
ablation catheters to reduce perforation risk TSP seems to be the
pivotal step in achieving CA procedure safety. We observed only one
pericardial tamponade following double transseptal access for AF
ablation procedure, which accounts for only 0.2\% of all TSPs. Safety
profile of our procedures is very similar to the recent publication on
fluoroless ICE-guided TSPs by Baykaner et al. (9) that also reported
very low pericardial tamponade (0.2\%) and overall complication rate
(0.7\%). Studies with large number of predominantly fluoroscopy-guided
CA procedures also report relatively low TSP-related complications rates
of 0.8\% and 0.7\%, respectively (1,3). On the other hand, some ``real
life'' registries record higher pericardial tamponade rates of 1.2\% (2)
and 1.3\% (17), respectively. Different adverse event definitions, study
populations, and CA techniques could have attributed to the
discrepancies of the results. In addition, nonuse of ICE was recognized
as one of the strongest independent predictors of cardiac perforation in
recent analysis of 102,398 patients who underwent AF ablation (18). In
line with our observations, the study acknowledges wider adoption of
intraprocedural ICE use to increase safety of CA procedures.

\textbf{Clinical implications}

Transseptal access is the key step in radiation-reducing strategies for
CA of left-sided arrhythmias. Our data suggests that an entirely
ICE-guided TSP enables operators to achieve completely fluoroless
ablation procedures without compromising safety and efficacy.
Fluoroscopy-based studies report, albeit rarely, complications such as
right atrial wall puncture, aortic root puncture and embolisms which
were not detected in the present study (1,2,18). Routine use of ICE does
not only provide real time visualization of IAS anatomy relevant to TSP
but also facilitates early recognition of potential procedural
complications such as formation of thrombus, signs of impending steam
pop or pericardial effusion. In our study we had two aborted cases due
to early recognition of thrombus with ICE which in theory prevented an
adverse event.

\textbf{Limitations}

The present study has some limitations. Retrospective design limits the
strength of our findings. Collection of data at a single center may
result in treatment bias, which could influence the outcomes. However,
our study cohort was representative of patients who undergo CA
procedures for left-sided arrhythmias (1-3, 9-11, 17-19). We did not
specifically assess the potential learning curve for completely
ICE-based TSP and CA ablation without the use of fluoroscopy. With
limited number of procedures and low complication rate it seems that our
study is underpowered to predict potential risk factors for pericardial
tamponade and other TSP-related complications. However, it is reasonable
to assume that the use of ICE prevented some of the potential adverse
events. Our findings in pediatric population and in patients with CIEDs
should be interpreted with caution since the numbers were low. Finally,
potential anatomical variations seen with ICE were not recorded
systematically, which limits our estimation of additional benefits of
ICE imaging. Further clinical studies are needed to establish
cost-effectiveness and clinical benefits of entirely ICE-guided TSPs.

\textbf{Conclusions}

Entirely ICE-guided TSPs for different left-sided tachycardias can be
safely and effectively performed in adult and pediatric population
without the use of fluoroscopy. However, caution is advised in patients
with CIEDs due to possible risk of lead dislocation.

\textbf{Author contributions:} all authors (D\selectlanguage{polish}Ž, \selectlanguage{english}BA, TPK, J\selectlanguage{polish}Š, \selectlanguage{english}NK, MJ and
MJ) made substantial contribution to the design of the study,
acquisition, analysis and interpretation of data. All authors also
actively participated in the drafting the manuscript, its final
revisions and corrections. All authors have read and approved the final
version of the manuscript.



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\textbf{Figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image1/image1}

\end{center}
\end{figure}

\textbf{Figure 1.} Intracardiac echocardiography-guided workflow for
achieving transseptal access.

Images obtained with the ICE probe placed in the right atrium with added
simplified graphic image in each panel for clarification. Panels A to H
show consecutive steps in achieving transseptal access. The guide wire
is marked with a red arrow in ICE images and represented with the red
line in graphic images, the tip of the dilator is marked with a purple
arrow in ICE images and represented with a purple line in graphic
images, the tip of the transseptal needle is marked with a white arrow
ICE images and represented with a black line in graphic images, the tip
of the long sheath is marked a green arrow in ICE images and represented
with a bolded green line in graphic images. VCS superior vena cava, PA
pulmonary artery, RA right atrium, LA left atrium, FO oval fossa, LSPV
left superior pulmonary vein.

\textbf{A} The guide wire is inserted into the VCS. \textbf{B} The long
sheath with the dilator inserted is advanced into the VCS over the guide
wire. \textbf{C} The guide wire is replaced with the transseptal needle
and the long sheath / dilator / transseptal needle assembly is withdrawn
toward the interatrial septum. \textbf{D} The tip of the dilator falls
on the oval fossa and its ``tenting'' can be seen. \textbf{E} The
transseptal needle is pushed through the dilator and advanced into the
LA cavity together with the tip of the dilator. \textbf{F} The
transseptal needle is withdrawn and the tip of the dilator remains in
the LA cavity. \textbf{G} The guide wire is advanced through the dilator
into the LSPV. \textbf{H} The long sheath and the dilator are advanced
over the guide wire into the LA cavity. The guide wire and the dilator
are withdrawn with the tip of the long sheath remaining in the LA
cavity.

\textbf{Tables}

\textbf{Table 1.} Baseline patient characteristics.\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
\textbf{Baseline characteristics} & \textbf{Overall
(n=524)}\tabularnewline
\midrule
\endhead
Age (Years) & 55.8 \selectlanguage{ngerman}± 17.6\tabularnewline
Male (\%) & 377 (72)\tabularnewline
Body Mass Index (kg/m\textsuperscript{2}) & 27.8 \selectlanguage{ngerman}± 5\tabularnewline
\textbf{Cardiovascular risk factors} &\tabularnewline
Arterial hypertension (\%) & 242 (46)\tabularnewline
Diabetes (\%) & 36 (6.8)\tabularnewline
Heart failure (\%) & 73 (14)\tabularnewline
Previous stroke / TIA (\%) & 10 (1.9)\tabularnewline
Vascular disease (\%) & 45 (8.6)\tabularnewline
CHA\textsubscript{2}DS\textsubscript{2}VASc score\selectlanguage{ngerman}\textsuperscript{§} &
1.4 \selectlanguage{ngerman}± 1\tabularnewline
\bottomrule
\end{longtable}\selectlanguage{ngerman}

TIA - transient ischemic attack;
CHA\textsubscript{2}DS\textsubscript{2}VASc -- stroke and thromboembolic
risk score (C congestive heart failure, H hypertension, A age, D
diabetes, S stroke, V vascular disease, A age 65-74 S sex category -
female)

\textbf{Table 2.} Procedural characteristics.\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
\textbf{Procedures} & \textbf{Overall (n=586)}\tabularnewline
\midrule
\endhead
Mean duration (min) & 161 \selectlanguage{ngerman}± 64\tabularnewline
Procedures in general anesthesia (\%) & 41 (7)\tabularnewline
\textbf{Procedure type} &\tabularnewline
AF and atypical flutter (\%) & 451 (77)\tabularnewline
Hybrid procedures for AF (\%) & 20 (3.4)\tabularnewline
Procedures for VT (\%) & 33 (5.6)\tabularnewline
Procedures for focal AT (\%) & 27 (4.6)\tabularnewline
Procedures for AP mediated tachycardia (\%) & 74 (13)\tabularnewline
Procedures for AVNRT (\%) & 1 (0.2)\tabularnewline
\textbf{Transseptal punctures} & \textbf{Overall (n=949)}\tabularnewline
Double punctures (\%) & 726 (76.5)\tabularnewline
Presence of CIED (\%) & 51 (5.4)\tabularnewline
Pediatric patients (\%) & 46 (4.8)\tabularnewline
Pediatric patients \textless{} 30 kg (\%) & 7 (0.7)\tabularnewline
RF needle technique (\%) & 4 (0.4)\tabularnewline
Unsuccessful (\%) & 2 (0.2)\tabularnewline
\bottomrule
\end{longtable}

AF - atrial fibrillation; VT - ventricular tachycardia; AT - atrial
tachycardia; AP - accessory pathway; CIEDs - cardiac implantable
electronic devices

\textbf{Table 3.} Procedural and transseptal access-related
complications.\selectlanguage{english}
\begin{longtable}[]{@{}lll@{}}
\toprule
& Ablation procedure \textbf{(n=586)} & Transseptal access
\textbf{(n=949)}\tabularnewline
\midrule
\endhead
Stroke / transient ischemic attack (\%) & 0 & 0\tabularnewline
Pericardial effusion (\%) & 6 (1.2) & 0\tabularnewline
Pericardial tamponade (\%) & 1 (0.2) & 2 (0.2)\tabularnewline
PSA surgery / intervention (\%) & 2 (0.3) & 0\tabularnewline
Esophageal injury (\%) & 0 & 0\tabularnewline
Transient phrenic palsy (\%) & 1 (0.2) & 0\tabularnewline
CIED lead dislocation (\%) & 1/36 procedures (2.7) & 1/51 punctures
(2)\tabularnewline
Total (\%) & 11 (1.9) & 3 (0.3)\tabularnewline
\bottomrule
\end{longtable}

PSA -- pseudoaneurysm; CIEDs -- cardiac implantable electronic devices

\selectlanguage{english}
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\end{document}

