Left Atrial Appendage Closure Guided by Integrated Echocardiography and Fluoroscopy Imaging Reduces Radiation Exposure
Left Atrial Appendage Closure Guided by Integrated Echocardiography and Fluoroscopy Imaging Reduces Radiation Exposure
Christiane Jungen 0 1
Tobias Zeus 0 1
Jan Balzer 0 1
Christian Eickholt 0 1
Margot Petersen 0 1
Eva Kehmeier 0 1
Verena Veulemans 0 1
Malte Kelm 0 1
Stephan Willems 0 1
Christian Meyer 0 1
0 1 Department of Cardiology-Electrophysiology, cNEP, cardiac Neuro- and Electrophysiology research group, University Heart Center, University Hospital Hamburg-Eppendorf , Hamburg, Germany , DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Luebeck , Hamburg, Germany , 2 Department of Cardiology, Pulmonology and Vascular Medicine, Medical Faculty, University Hospital Duesseldorf , Duesseldorf , Germany
1 Editor: Giuseppe Andò, University of Messina , ITALY
Funding: CM and CE are funded by the Research
Committee of the medical faculty of the University of
Duesseldorf. CM also holds a research grant from
Biotronik and the Hans-und-Gertie-Fischer Stiftung.
The study was supported with a restricted grant from
the federal state government of
North-RhineWestphalia and the European Union (EFRE-Program
„Med in NRW”, support code 005-GW01-235A). The
funders had no role in study design, data collection
and analysis, decision to publish, or preparation of
To investigate whether percutaneous left atrial appendage (LAA) closure guided by
automated real-time integration of 2D-/3D-transesophageal echocardiography (TEE) and
fluoroscopy imaging results in decreased radiation exposure.
Methods and Results
In this open-label single-center study LAA closure (AmplatzerTM Cardiac Plug) was
performed in 34 consecutive patients (8 women; 73.1±8.5 years) with (n = 17, EN+) or without
(n = 17, EN-) integrated echocardiography/fluoroscopy imaging guidance (EchoNavigator1
[EN]; Philips Healthcare). There were no significant differences in baseline characteristics
between both groups. Successful LAA closure was documented in all patients. Radiation
dose was reduced in the EN+ group about 52% (EN+: 48.5±30.7 vs. EN-: 93.9±64.4 Gy/
cm2; p = 0.01). Corresponding to the radiation dose fluoroscopy time was reduced (EN+:
16.7±7 vs. EN-: 24.0±11.4 min; p = 0.035). These advantages were not at the cost of
increased procedure time (89.6±28.8 vs. 90.1±30.2 min; p = 0.96) or periprocedural
complications. Contrast media amount was comparable between both groups (172.3±92.7 vs.
197.5±127.8 ml; p = 0.53). During short-term follow-up of at least 3 months (mean: 8.1±5.9
months) no device-related events occurred.
Competing Interests: This study was funded in part
by Biotronik. JB receives honoraria for lectures from
Philips Healthcare. TZ receives honoraria for lectures
from St. Jude Medical. There are no patents,
products in development or marketed products to
declare. This does not alter the authors' adherence to
all the PLOS ONE policies on sharing data and
Abbreviations: ACP, AmplatzerTM Cardiac Plug; AF,
Atrial fibrillation; EHRA, European Heart Rhythm
Association; EN, EchoNavigator; EN+, Procedures
performed using the EchoNavigator; EN-, Procedures
performed without the EchoNavigator; LAA, Left atrial
appendage; LCX, Left circumflex artery; SD,
Standard deviation; SJM, St. Jude Medical1; TEE,
Automated real-time integration of echocardiography and fluoroscopy can be incorporated
into procedural work-flow of percutaneous left atrial appendage closure without prolonging
procedure time. This approach results in a relevant reduction of radiation exposure.
Percutaneous left atrial appendage (LAA) closure is currently under investigation as a
promising catheter-based approach for stroke prevention in patients with atrial fibrillation (AF)
[1,2,3]. This is important since the LAA is the source of thrombi in >90% of affected patients
with nonvalvular AF  while oral anticoagulation still bears several limitations including
bleeding risk . Importantly, LAA closure still remains technically challenging . Recently,
a novel system enabling integrated echocardiography and fluoroscopy imaging
(EchoNavigator1 [EN]), Philips Healthcare), which might at least partly overcome these limitations
including radiation exposure, has been introduced [6,7]. The EN integrates in real-time information
from 2D-/3D-transesophageal echocardiography (TEE) and fluoroscopy in the same
anatomical alignment enabling improved visualization of catheters, guidewires and devices in relation
to relevant anatomical structures . The usefulness of this novel imaging approach during
LAA closure procedures has not been systematically investigated so far. Herein, we investigated
the utility of LAA closure guided by integrated echocardiography and fluoroscopy imaging.
We hypothesized that this approach decreases radiation exposure.
The protocol for this trial and supporting CONSORT checklist are available as supporting
information (S1 CONSORT Checklist and S1 Protocol).
In this open-label single-center study patients with nonvalvular AF, a CHA2DS2-VASc score of
1, a relative contraindication to oral anticoagulation, and a life expectancy of at least 2 years
 were assigned by a computer software to LAA closure with (EN+) or without (EN-) the
guidance of automated real-time integration of 2D-/3D- TEE and fluoroscopy imaging (Fig 1).
The primary endpoint of this study was the change of total radiation dose. The secondary
endpoints were changes of fluoroscopy time, procedure time and contrast media amount.
Successful LAA closure (residual flow <5mm) and acute (7-day) occurrence of death, ischemic
stroke, systemic embolism and procedure or device related complications requiring major
cardiovascular or endovascular intervention were determined [8,9].
The ethics review committee of the Heinrich-Heine-University Duesseldorf (Ethics review
committee of the medical faculty, building 13.41, Moorenstrasse 5, 40225 Duesseldorf,
Germany) approved this study and written informed consent was given by each patient. Patients
undergoing LAA closure between February 2012 and March 2014 were included. Philips did
not influence study design, data analysis, or manuscript preparation.
Fig 1. CONSORT flow chart.
Percutaneous catheter-based LAA closure in all patients was performed with the AmplatzerTM
Cardiac Plug (ACP) (AGA-St-Jude, Minneapolis, MN, USA) under conscious sedation by
using boluses of midazolam and a continuous infusion of propofol (2%). A TEE probe was
introduced to rule out intracardiac/LAA thrombus. An initial bolus of unfractionated heparin
(80–100 IU/kg of body weight) was administered prior to a single transseptal puncture by
using the modified Brockenbrough technique (LAMPTM, 45°, SWARTZTM, St. Jude Medical1,
St. Paul, USA; BRKTM, SJM) under TEE control. The heparin dose was adjusted during the
procedure in all patients to achieve an activated clotting time >300 seconds. LAA orifice diameter
and landing zone were measured by using 2D-TEE (mid-esophageal view at 0°, 45°, 90°, 135°)
and angiography (right anterior oblique 30/25 caudal and right anterior oblique 30/15 cranial).
A 13 French delivery sheath (45°x45° Amplatzer TorqVue1, SJM) was used for LAA
angiography and ACP positioning. The device was chosen to be 10–20% larger than the maximum
diameter of the LAA . The ACP lobe was placed 1mm from the LAA orifice with the device’s
long axis being positioned parallel to the LAA wall with the disc of the ACP aligned with the
plane of the LAA orifice. After performing a tug test to ensure a secure fit, the device was
released. A waiting period of at least 10 minutes was used to confirm a stable position of the
LAA occluder. Clopidogrel and acetylsalicylic acid were prescribed for 3 months, followed by
acetylsalicylic acid intake alone.
Integrated echocardiography and fluoroscopy imaging: The EchoNavigator
For automated real-time integration of echocardiography and fluoroscopy imaging a novel
image integration system, the EN (Philips Healthcare, Best, The Netherlands), has been
introduced. The system enables presentation of echocardiographic images in the same anatomical
alignment as the C-arm of the fluoroscopy unit (“C-arm” view) so that both images of 2D-/
3D-TEE and fluoroscopy (“X-Ray” view) are concordant in size and orientation in 3D space
. Changes in angulation, rotation, or position of the TEE probe are immediately registered
and updated on fluoroscopy images . Movement of the C-arm induces updates of the
echocardiography images with the same angulation. In a third window, the interventional
cardiologist can simultaneously rotate and zoom an echocardiography image (“Free” view)
independently from the echocardiographer by using a tableside control. In a fourth window,
conventional echocardiographic views (“Echo” view) are available. Each separate image display
can further be modified by using features like contrast, panning or cropping. Depending on
operator’s preferences two, three, or four windows are presented (Fig 2). Additionally, a
“marker feature” (Fig 3) allows setting markers on typical anatomical regions in the
echocardiography image. These markers are simultaneously displayed in real-time on the fluoroscopy
image. This feature is helpful to recognize anatomical landmarks including the interatrial
septum, the LAA orifice, the so called ridge (crista) between LAA and left pulmonary veins, and/
or the left circumflex artery (LCX). These markers have been introduced to support orientation
in general and to facilitate catheter and device guidance during live fluoroscopy. Usually,
labelling of soft tissue targets takes place in the echocardiographic image, which is then displayed
on the other image modality, e.g. in fluoroscopy. When the gantry is moved all markers are
automatically updated on the fluoroscopy image without obvious lag time or need for
re-registration. During LAA closure procedures this approach might support (1.) transseptal puncture,
(2.) anatomical orientation and device positioning, and (3.) verification of adequate sealing and
device stability. Therefore, depending on the interventionalist’s choice, the transseptal
puncture was facilitated after setting a marker at the optimal puncture site by using the x-plane
feature allowing simultaneous demonstration of two orthogonally orientated echocardiographic
image planes (Fig 2). Afterwards, the EN was used for anatomical orientation in the left atrium
and for positioning of the occluder within the LAA (Fig 3) following LAA measurements. The
LAA orifice and additional anatomical landmarks were marked and optimal device positioning
was evaluated in different angles simultaneously by using the C-Arm-, X-Ray-, Free-, and/or
Echo view. After device release correct positioning was verified in 2D-/3D-TEE combined with
color doppler and fluoroscopy/angiography (Fig 4) .
Echocardiographic measurements were performed in accordance with the guidelines of the
American Society of Echocardiography  as described in detail before . Obtained 2D-/
3D-TEE images were stored in cine-loop format and analyzed in Xcelera R3.2L1 (Version 3
2011, Philips Medical Systems, Best, Netherlands). 3D-TEE images were recorded as 3D zoom
dataset and analyzed with the multiplanar reconstruction mode in QLAB-3DQ (Version 8,
Philips Medical Systems, Best, Netherlands) [13,14,15,16]. Left atrial diameter and area as well
as calculation of the left ventricular ejection fraction were performed by using the Simpson
Fig 2. Overview of integrated echocardiography and fluoroscopy imaging. The image acquisition angles during transseptal puncture are depicted in the
lower right corner of each image. A+B) Concordant views of TEE and fluoroscopy images. C) In the “Free view” echocardiographic images can be rotated
and zoomed independently from the echocardiographer by using a tableside control. D) Conventional echocardiographic view using the x-plane mode for
identification of the preferred transseptal puncture site (Septum, blue). Sheath with transseptal needle; Pigtail cath. = pigtail catheter; RV cath. = catheter in
the right ventricle.
biplane method [17,18]. We also compared several LAA measurements in different imaging
methods (S1 Table and S1 Fig). In 2D-TEE the maximum and minimum diameter of the LAA
orifice were obtained in orthogonal planes and measured as previously recommended .
The LAA orifice area was then calculated by using the equation : LAA orifice area = π x
(Dmax/2) x (Dmin/2). For comparison with 3D-TEE derived data, the larger of the two
calculated orifice areas was used .
Continuous variables are presented as mean values with standard deviation (SD) and
categorical variables as numbers. For comparisons between groups with continuous variables an
unpaired t-test was used. To compare differences across subgroups with not normally
distributed data we used the Mann-Whitney test. To compare multiple subgroups of normally
distributed data a one-way ANOVA was used. All analyses were performed using Prism 5 (GraphPad
Prism 5.0, GraphPad Software Inc., San Diego, USA). As reported by prior studies showing a
significant reduction of fluoroscopy exposure, we assumed a reduction by 10% compared with
conventional procedures. The prospectively calculated sample size using 2-sided t-test analysis
aiming for a power of 95% and an alpha of 0.05 was 14 patients per group. With a drop-out
rate of 15% we assumed a group size of 17 patients.
Fig 3. Visualization of the LAA and surrounding structures preceding occluder positioning. The LAA orifice (red), the crista (yellow), and the septum
(blue) are marked by landmark setting. A) 2D-TEE image in the same anatomical alignment as the C-arm. B) Outlines of 2D-TEE (pink lines) are fused with
the fluoroscopy image. C+D) 2D-TEE with anatomical landmarks depicted in different angles. Note the sheath in close proximity to the left superior
pulmonary vein as supported by the matching landmarks in different views. RV cath. = catheter in the right ventricle.
Patients’ baseline characteristics are depicted in Table 1. Thirty-four patients (8 women; mean
age: 73.1±8.5 years; body mass index 28.4±4.4) were included. For all patients, a
CHA2DS2VASC score between 1 and 6 (mean 3.6±1.2) and a HAS-BLED score between 1 and 4 (mean
2.7±0.9) were calculated. Calculated stroke and bleeding risks did not differ between the EN+
(n = 17) and EN- (n = 17) group.
ture” was used in all patients in the EN+ group (for a representative image integration
demonstrating the EN see S1 and S2 Moving Images). Covering of the LAA orifice by the disk of the
ACP was documented by TEE and angiography in all patients in the EN+ and the EN- group
Fig 4. Evaluation of adequate device position and stability by using 3D-TEE and fluoroscopy. After LAA occluder release correct positioning is verified
simultaneously by rotation and zoom of the 3D-TEE image and angiography. The LAA occluder is shown in the 3D-TEE “Free view” (A) by using the tableside
control and the fluoroscopy (B) demonstrating the relationship to surrounding structures (LCX, crista). Note the relatively large crista which could not be fully
covered by the disc of the LAA occluder, while contrast agent injection demonstrated good LAA sealing.
LAA measurements varied relative to the used imaging modality. The maximum LAA
orifice diameter (ANOVA; F = 1.589, p = 0.2110) and length (ANOVA; F = 0.6821, p = 0.5087)
did not differ between 2D-, 3D-TEE and angiography. LAA orifice area was smaller in 2D-TEE
measurements (2.4±4 cm2) compared to 3D-TEE (2.9±1.1 cm2; p = 0.01) (S1 Table). The mean
device size did not differ between the EN+ and the EN- group. In 5 of 34 patients (15%) devices
needed to be changed during the procedure due to initial mis-sizing (2 times in the EN+ and 3
times in the EN- group).
Primary and secondary endpoints
Total radiation dose was reduced about 52% in the EN+ group (EN+: 48.5±30.7 Gy/cm2 vs.
EN-: 93.9±64.4 Gy/cm2; p = 0.01) compared to the EN- group (Table 2). Corresponding to the
radiation dose fluoroscopy time was reduced (EN+: 16.7±7 minutes vs. EN-: 24.0±11.4
minutes; p = 0.035). Procedure time (EN+: 89.6±28.8 minutes vs. EN-: 90.1±30.2 minutes;
p = 0.96) and contrast media amount (EN+: 172.3±92.7 ml vs. EN-: 197.5±127.8 ml; p = 0.53)
did not differ between both groups (Table 2).
No periprocedural cardiovascular events and procedure or device related complications
requiring major cardiovascular or endovascular intervention occurred (Table 2). During short-term
follow-up of at least 3 months (mean: 8.1±5.9 months) no cerebrovascular complications
occurred. Unfortunately, one multimorbid patient (female, 61 years, EN+ group) with a
porcelain aorta and previous transapical aortic valve implantation died following paravalvular leak
closure (Amplatzer Vascular Plug III 10 x 5 mm; AGA Medical Corporation, Plymouth,
Table 1. Baseline characteristics. ACE: angiotensin converting enzyme; AF: atrial fibrillation; INR: international normalized ratio; PCI: percutaneous
coronary intervention; SD: standard deviation.
Total (n = 34)
EN+ (n = 17)
EN- (n = 17)
Minnesota) due to a rapidly progressive aortic regurgitation (pressure half time 440 ms, Jet/
LVOT 28%). The paravalvular leak closure had to be performed due to cardiac
decompensation and advanced dyspnoea. There was no evidence for dislocation or thrombus formation
Total (n = 34)
EN+ (n = 17)
EN- (n = 17)
related to the LAA occluder. In one patient of the EN- group a slight peri-device flow was
documented 3 months after LAA closure and oral anticoagulation was reinitiated due to the
patient’s wish to reduce the risk of thromboembolism. During follow-up no accompanying
cardiovascular events occurred.
The major findings of the present study are: 1. Automated real-time integration of
echocardiography and fluoroscopy was found to reduce radiation dose and fluoroscopy time during
percutaneous left atrial appendage closure. 2. This approach did not prolong procedure time or
increase periprocedural complications.
The combination of TEE and fluoroscopy is well established for percutaneous LAA closure
due to the well known limitations of each of these modalities [15,20]: 2D-TEE ensures imaging
quality of relevant anatomical structures but often needs several adjustments to visualize the
course of intracardiac catheters and their relationship especially with the LAA orifice and
body. The latter are only partly overcome by 3D-TEE [13,16]. Fluoroscopy optimally visualizes
catheters, guidewires, and devices but is limited by its 2D projections of the complex 3D
anatomy of the LAA and surrounding structures. The automated real-time fusion of
echocardiography and fluoroscopy combines the advantages of both imaging modalities. This might improve
percutaneous LAA closure as supported by the present findings.
Integrated echocardiography and fluoroscopy imaging during LAA
According to EHRA/EAPCI expert consensus on catheter-based LAA occlusion TEE is the
gold standard for imaging the LAA and guiding LAA closure . Nevertheless, TEE is an
integral part for guidance in most but not all LAA occlusion procedures. Whether the automated
real-time integration of 2D-/3D-TEE and fluoroscopic images in the same anatomical
alignment might increase the number of TEE guided procedures is unknown. However, several
potential benefits might be noteworthy . First, landmark setting supports complex
transseptal punctures  and LAA occluder positioning. Second, objects which are best visualized in
different imaging modalities (i.e. the LAA orifice in echocardiography and the device in
fluoroscopy) are directly and in real-time displayed in the same orientation. Especially during
device deployment, when the anatomical target is best visualized in ultrasound and the device
in fluoroscopy, the integrated imaging displays both modalities in the same perspective so that
mental work is reduced for the operator. Third, integrated imaging provides in real-time
several information for device deployment and stability in variable, patient-specific LAA
anatomies in one image. Features like free rotation and zoom of an echocardiographic image, which
are controlled by a tableside control, add additional information to TEE color doppler and
angiography regarding adequate LAA sealing and device stability. Some of these advantages
might also be realized by intracardiac echocardiography . This cannot be answered by the
present study. The wider use of the latter might be influenced by operateur preferences and its
availability while the EN incorporates modalities which are available in every catheterization
Importantly, although the integrated imaging system can facilitate the procedure for the
operator, it has also a potential safety concern. A shift between both imaging modalities may
occur, so that the two images will not be displayed in the same orientation any more. Although
this kind of shift is visualized on the screen (see green coloring of TEE probe in Figs 2 and 3
which would turn red) procedural mistakes could occur.
The finding that the radiation exposure was reduced by using integrated imaging suggests that
the software module facilitates left atrial visualization. It is likely that integrated images of the
LAA obtained with echocardiography and fluoroscopy predominantly reduced the need for
multiple LAA angiograms. Whether or how a pre-procedure computer tomographic
angiography or an intra-procedure C-arm rotational angiography might impact the identification of the
optimal gantry position for device deployment in challenging cases was beyond the scope of
the present study and needs to be determined. Although the impact of radiation dose reduction
is not known, it may be relevant for several patient populations (e.g. obese and younger
patients) and may in the future reduce the lifetime risk of cancer for medical staff performing
fluoroscopy guided procedures over many years .
While radiation exposure was reduced, procedure time was similar in both groups. This
might be in part explained by the fact that landmark setting and measurements during the
procedure are time-consuming . This is in line with findings by Sündermann and colleagues
who nicely demonstrated the feasibility of using the EN during edge-to-edge mitral valve repair
. In addition, angiographies are relatively standardized in our approach. The resulting
procedure time is still a noteworthy issue. Whether technical improvements like direct overlay
might overcome this and other limitations has not been systematically investigated. It needs to
be demonstrated if those upgrades might finally translate into improved outcome and patient
Procedural success and follow-up
Although early in its clinical use, we investigated the potential impact of integrated imaging on
Importantly, we only included a relatively small number of patients undergoing LAA
closure due to the fact that the aim of the study was to investigate whether integrated imaging
reduces radiation exposure. Regarding the outcome the amount of patients is of course critical.
Since the overall complication rate is expected to be higher (serious pericardial effusion about
1–2%, device embolization *1%, ischemic stroke *1%)  no reliable conclusion can be
drawn regarding the safety of integrated imaging from the present data. Variables like
anatomical variations or difficult TEE image acquisition may influence procedural success. Whether
and how the presented approach might be useful to overcome technical challenges in some
patients is yet not known. Further large-scale trials are warranted to ultimately assess the safety
of this novel fusion imaging approach. However, there are no reasons to expect any unforeseen
limitations when automated real-time image integration is used since its reliability and stability
could be shown.
Automated real-time integration of echocardiography and fluoroscopy can be easily
incorporated into procedural work-flow of percutaneous left atrial appendage closure without
prolonging procedure time. This approach results in a relevant reduction of radiation exposure for
patients and medical staff.
S1 Table. Comparison of 2D-TEE and 3D-TEE LAA measurements. The LAA orifice area
was smaller in 2D-TEE measurements (2.4±1.4 cm2) compared to 3D-TEE (2.9±1.1 cm2;
p = 0.01). The maximum LAA orifice diameter (ANOVA; F = 1.589, p = 0.21) and length
(ANOVA; F = 0.6821, p = 0.51) did not differ between 2D-, 3D-TEE and angiography.
S1 Fig. LAA characterization by using 2D- (A), 3D-TEE (B), and angiography (C). All three
imaging modalities show different morphological details in a patient with nearly identical
diameters of the LAA orifice. Note the LCX which is optimally visualized in 2D-TEE only.
3D-TEE derived LAA measurements have been described to be more accurate reflecting the
“real” LAA anatomy and morphology. In our experience a “stepwise approach” combining
different imaging modalities in a systematic manner give greater confidence during critical steps
of the procedure.
S1 Moving Image. Integrated echocardiography and fluoroscopy imaging during LAA
closure. First, the conventional echocardiographic view using the x-plane mode (left panel) and
the fluoroscopic view (right panel) including angiography are displayed. Outlines of 2D-TEE
(right panel, pink lines) are fused with the fluoroscopy image. Next, in the four window view
the 2D-TEE image (lower left panel) is in the same anatomical alignment as the C-arm (lower
right panel). In a third window (upper left panel), the interventional cardiologist can
simultaneously rotate and zoom an echocardiography image (“Free” view) independently from the
echocardiographer by using a tableside control. In the fourth window (upper right panel), the
left atrium is shown in the conventional echocardiographic views (“Echo” view). Markers
demonstrating the crista and LCX have been used.
S2 Moving Image. 3D Visualization of the left atrium during integrated imaging.
Fluoroscopy (lower right) and 3D-TEE imaging are used to confirm correct device positioning. The
LAA occluder is scanned in the 3D-TEE “Free view” (upper left) by using the tableside control
demonstrating the relationship to surrounding structures (LCX, crista). The sheath is displayed
in the upper right panel. Note the large crista, which could not be fully covered by the occluder.
We thank Friederike Jonas for excellent technical support.
Conceived and designed the experiments: CJ CM. Performed the experiments: TZ JB CM.
Analyzed the data: CJ CE CM. Contributed reagents/materials/analysis tools: CE JB MK CM.
Wrote the paper: CJ TZ JB CE MP EK VV MK SW CM.
based left atrial appendage closure. Circ Cardiovasc Imaging. 2011; 4: 514–523. doi: 10.1161/
CIRCIMAGING.111.963892 PMID: 21737601
1. Reddy VY , Möbius-Winkler S , Miller MA , Neuzil P , Schuler G , Wiebe J , et al. Left atrial appendage closure with the watchman device in patients with a contraindication for oral anticoagulation . J Am Coll Cardiol . 2013 ; 61 : 2551 - 2556 . doi: 10.1016/j.jacc. 2013 . 03.035 PMID: 23583249
2. Landmesser U , Holmes DR . Left atrial appendage closure: a percutaneous transcatheter approach for stroke prevention in atrial fibrillation . Eur Heart J . 2012 ; 33 : 698 - 704 . doi: 10.1093/eurheartj/ehr393 PMID: 22041550
3. Lockwood SM , Alison JF , Obeyesekere MN , Mottram PM . Imaging the Left Atrial Appendage Prior to , During, and After Occlusion. J Am Coll Cardiol Img . 2011 ; 4 : 303 - 306 .
4. Stoddard MF , Dawkins PR , Prince CR , Ammash NM . Left atrial appendage thrombus is not uncommon in patients with acute atrial fibrillation and a recent embolic event: a transesophageal echocardiographic study . J Am Coll Cardiol . 1995 ; 25 : 452 - 459 . PMID: 7829800
5. Reddy VY , Sievert H , Halperin J , Doshi SK , Buchbinder M , Neuzil P , et al. Percutaneous Left Atrial Appendage Closure vs Warfarin for Atrial Fibrillation . JAMA. 2014 ; 312 : 1988 - 1998 . doi: 10.1001/jama. 2014.15192 PMID: 25399274
6. Sündermann SH , Biaggi P , Grünenfelder J , Gessat M , Felix C , Bettex D , Falk V , et al. Safety and feasibility of novel technology fusing echocardiography and fluoroscopy images during MitraClip interventions . EuroIntervention . 2014 ; 9 : 1210 - 1216 . doi: 10.4244/EIJV9I10A203 PMID: 24103772
7. Gafoor S , Schulz P , Heuer L , Matic P , Franke J , Bertog S , et al. Use of EchoNavigator, a Novel Echocardiography-Fluoroscopy Overlay System , for Transseptal Puncture and Left Atrial Appendage Occlusion. J Interv Cardiol . 2015 ; 28 : 215 - 217 . doi: 10.1111/joic.12170 PMID: 25676602
8. Viles-Gonzalez JF , Kar S , Douglas P , Dukkipati S , Feldman T , Horton R , et al. The Clinical Impact of Incomplete Left Atrial Appendage Closure With the Watchman Device in Patients With Atrial Fibrillation . J Am Coll Cardiol . 2012 ; 59 : 923 - 929 . doi: 10.1016/j.jacc. 2011 . 11.028 PMID: 22381428
9. Camm AJ , Kirchhof P , Lip GY , Schotten U , Savelieva I , Ernst S , et al. Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC) . Eur Heart J . 2010 ; 31 : 2369 - 2429 . doi: 10.1093/eurheartj/ehq278 PMID: 20802247
10. Nietlispach F , Gloekler S , Krause R , Shakir S , Schmid M , Khattab AA , et al. Amplatzer left atrial appendage occlusion: single centre 10-year experience . Catheter Cardiovasc Interv . 2013 ; 82 : 283 - 289 . doi: 10.1002/ccd.24872 PMID: 23412815
11. Douglas PS , Garcia MJ , Haines DE , Lai WW , Manning WJ , Patel AR , et al. ACCF/ASE/AHA/ASNC/ HFSA/HRS/ SCAI/SCCM/SCCT/SCMR 2011 Appropriate Use Criteria for Echocardiography. A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Society of Echocardiography, American Heart Association, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Critical Care Medicine, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance American College of Chest Physicians. J Am Soc Echocardiogr . 2011 ; 24 : 229 - 267 . doi: 10.1016/j.echo. 2010 . 12.008 PMID: 21338862
12. Meyer C , Rana OR , Saygili E , Gemein C , Becker M , Nolte KW , et al. Augmentation of Left Ventricular Contractility by Cardiac Sympathetic Neural Stimulation. Circulation . 2010 ; 121 : 1286 - 1294 . doi: 10. 1161/CIRCULATIONAHA.109.874263 PMID: 20212280
13. Nucifora G , Faletra FF , Regoli F , Pasotti E , Pedrazzini G , Moccetti T , et al. Evaluation of the left atrial appendage with real-time 3-dimensional transesophageal echocardiography: implications for catheter-
14. Cruz-Gonzalez I , Yan BP , Lam Y. Left atrial appendage exclusion: state-of-the-art . Catheter Cardiovasc Interv . 2010 ; 75 : 806 - 813 . doi: 10.1002/ccd.22344 PMID: 20088009
15. Balzer J , Kelm M , Kuhl HP . Real-time three-dimensional transoesophageal echocardiography for guidance of non-coronary interventions in the catheter laboratory . Eur J Echocardiogr . 2009 ; 10 : 341 - 349 . doi: 10.1093/ejechocard/jep006 PMID: 19211569
16. Balzer J , van Hall S , Rassaf T , Boring Y , Franke A , Lang RM , et al. Feasibility , safety, and efficacy of real-time three-dimensional transoesophageal echocardiography for guiding device closure of interatrial communications: initial clinical experience and impact on radiation exposure . Eur J Echocardiogr . 2010 ; 11 : 1 - 8 . doi: 10.1093/ejechocard/jep116 PMID: 19755469
17. Lang RM , Bierig M , Devereux RB , Flachskampf FA , Foster E , Pellikka PA , et al. Recommendations for chamber quantification: a report from the American Society of Echocardiography's Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology . J Am Soc Echocardiogr . 2005 ; 18 : 1440 - 1463 . PMID: 16376782
18. Balzer J , Kühl H , Rassaf T , Hoffmann R , Schauerte P , Kelm M , et al. Real-time transesophageal threedimensional echocardiography for guidance of percutaneous cardiac interventions: first experience . Clin Res Cardiol . 2008 ; 97 : 565 - 574 . doi: 10.1007/s00392- 008 - 0676 - 3 PMID: 18512094
19. Shah SJ , Bardo DM , Sugeng L , Weinert L , Lodato JA , Knight BP , et al. Real-time three-dimensional transesophageal echocardiography of the left atrial appendage: initial experience in the clinical setting . J Am Soc Echocardiogr . 2008 ; 21 : 1362 - 1368 . doi: 10.1016/j.echo. 2008 . 09.024 PMID: 19041579
20. Faletra FF , Pedrazzini G , Pasotti E , Muzzarelli S , Dequarti MC , Murzilli R , et al. 3D TEE during catheter-based interventions . J Am Coll Cardiol Img . 2014 ; 7 : 292 - 308 .
21. Meier B , Blaauw Y , Khattab AA , Lewalter T , Sievert H , Tondo C , et al. EHRA/ EAPCI expert consensus statement on catheter-based left atrial appendage occlusion . EuroIntervention . 2015 ; 10 : 1109 - 1125 . doi: 10.4244/ EIJY14M08_18 PMID: 25169595
22. Berti S , Paradossi U , Meucci F , Trianni G , Tzikas A , Rezzaghi M , et al. Periprocedural Intracardiac Echocardiography for Left Atrial Appendage Closure. JACC: Cardiovasc Interv . 2014 ; 7 : 1036 - 1044 .
23. Reddy VY , Morales G , Ahmed H , Neuzil P , Dukkipati S , Kim S , et al. Catheter ablation of atrial fibrillation without the use of fluoroscopy . Heart Rhythm . 2010 ; 7 : 1644 - 1653 . doi: 10.1016/j.hrthm. 2010 . 07. 011 PMID: 20637313