Discussion
Dextrocardia is a rare congenital condition with an incidence of about 1
in 10,0001,the incidence of atrial septal aneurysm is
about 2.4%4, and the combination of arrhythmias is
even rarer, making catheter ablation more difficult due to its
anatomical variants, combined with abnormal pulmonary venous connections
or other visceral transposition1,2. This article
exhibits a case of a female patient with dextrocardia combined with
atrial septal aneurysm and focal atrial tachycardia who underwent
successful radiofrequency ablation.
In this case, the patient had focal atrial tachycardia and atrial septal
aneurysm, and congenital dextrocardia at the same time, which brought
great challenges to our radiofrequency ablation. Fortunately, we
successfully and safely completed the radiofrequency ablation procedure
and summarized as follows, 1)In patients with dextrocardia undergoing
atrial tachycardia, a thorough preoperative evaluation to understand the
specific structural variants of the heart is essential, such as cardiac
ultrasound and cardiac enhancement CT, which help the operator to
perform a thorough preoperative evaluation and formulate an effective
ablation strategy, reduce the number of unnecessary punctures and
operations, shorten the procedure time and ensure the safety of the
procedure. 2)Because the position of the atrium of patients with
dextrocardia is opposite to that of ordinary people, the right anterior
oblique position and the left anterior oblique position should to be
exchanged during fluoroscopy, which is different from the fluoroscopy
position of our normal patients. Better assessment of the condition and
revision of surgical strategies during surgery. 3) ICE is an advanced
application in electrophysiological surgery that can provides real-time
imaging modalities with spectral and color Doppler capabilities,
integrate directly with electroanatomical mapping systems, can visualize
complex anatomical structures, allowing the operator to develop
individual ablation strategies, thereby avoiding ineffective ablation
and/or reducing the occurrence of surgical
complications8. In this case, we administered ICE
before performing ablation. On the one hand, confirming that there is no
thrombosis in the left atrial appendage, which is the premise of safe
operation. On the other hand, a better understanding the special heart
structures can guide atrial septal puncture, especially in the presence
of an atrial septal aneurysm, and better reaching the designated
ablation site. 4) The CARTO 3D imaging system is an important part of
the intraoperative procedure, which allows for effective 3D
reconstruction of the cardiac structure before ablation, helping the
operator to understand the spatial structure of the heart better and
improving the safety and effectiveness of intraoperative
catheterization. 4)For patients who failed atrial tachycardia
radiofrequency ablation in conventional locations, attention should also
be paid to non-conventional ablation sites such as the non-coronary
sinus during intraoperative electrical activation mapping.
Antiarrhythmic drugs and transcatheter cardiac radiofrequency ablation
are the conventional treatment modalities for atrial tachycardia. With
the growing experience of transcatheter cardiac radiofrequency ablation,
the procedure’s success rate has improved significantly over the past
few years. Catheter radiofrequency ablation is routinely performed in
experienced centers and, given the side effects of antiarrhythmic drugs,
which has become the treatment of choice for atrial tachycardia.
However, the anatomical variation of cardiac structure in patients with
dextrocardia is still not well known, let alone the presence of atrial
septal aneurysm, so the difficulty of successful ablation will
undoubtedly be further increased if arrhythmias are concomitant, which
has rarely been reported so far.
In 1994, Wu et al10 first reported catheter
radiofrequency ablation of a patient with a mirrored dextrocardia and
persistent atrioventricular reentrant tachycardia. The procedure was
successful and without complications, demonstrating the feasibility of
radiofrequency ablation in treating patients with dextrocardia. Vaseghi
et al11 reported a patient with mirror-image
dextrocardia combined with counter-clockwise atrial flutter in the right
atrial, of which the tachycardia was cured by ablation of the
tricuspid-inferior vena cava isthmus, the application value of ECG in
guiding the ablation of patients with dextrocardia complicated with
arrhythmia is also proposed at the same time. Benjamin et
al12 proposed in the radiofrequency ablation of
patients with dextrocardia complicated with atrial fibrillation and
atrial flutter, the use of CARTO for electroanatomical localization of
the right atrium, combined with intracardiac echocardiography and
fluoroscopy for atrial septal puncture, is helpful for the operator
better judge the opposite anatomical position, improving the accuracy
and success rate of the operation. Vurgun et al13reported the first case of catheter ablation of scar-associated atrial
flutter due to surgical repair of atrial septal defects with
dextrocardia and complex venous anomalies. They placed three long
sheaths through the femoral vein at the superior vena cava and right
atrium to stabilize and control the catheter. Activation mapping with
Carto-3D system suggested that the tachycardia spread between the two
scars. Tachycardia stops when linear
ablation is performed between two scars, demonstrating that
radiofrequency ablation with an electroanatomical mapping system is
effective and safe in such patients. Zhang et al14reported 19 patients with dextrocardia and arrhythmia who underwent
successful transcatheter cardiac radiofrequency ablation, demonstrating
that radiofrequency ablation is safe, effective, and feasible in such
patients. Combining echocardiography, cardiac computed tomography, and
3D mapping, the application of 3D reconstruction can improve the success
rate of catheter ablation. Zhou et al15 reported 10
patients with dextrocardia and arrhythmias undergoing catheter ablation,
including atrioventricular nodal reentrant tachycardia, atrioventricular
reentrant tachycardia, intra-atrial reentrant tachycardia, and focal
atrial atrial fibrillation. Among them, 9 cases were immediately
successful during the operation, and no operative complications
occurred. All patients were followed up for 6.3 ± 3.5 years without any
arrhythmia recurrence. Proposing that paying attention to the anatomical
abnormality of the dextrocardia and the cardiac structure, as well as
the adjacent relationship of the surrounding structures, is the key to
the success of catheter ablation, and recommending setting the ECG leads
in a mirror mode, and invert the fluoroscopic image horizontally, which
is conducive to the understanding of intraoperative anatomical
positioning. In recent years, in addition to radiofrequency ablation,
balloon cryoablation has also been used to treat arrhythmias in patients
with dextrocardia. Akkaya et al16 reported the first
case of cryoballoon ablation in a patient with focal atrial tachycardia
in dextrocardia. The successful ablation of abnormal potentials
originating in the superior pulmonary vein inferior to the ramus under
the guidance of the Ensite system suggests that cryoballoon ablation may
also be safe and feasible in patients with dextrocardia combined with
arrhythmias.
In summary, the key to successful catheter ablation in patients with
dextrocardia, atrial septal aneurysm, and arrhythmia lies in the
preoperative comprehensive analysis of the patient’s examination data to
develop a surgical strategy that will lead to faster and better access
to the procedure. Necessary preoperative tests include
electrocardiogram, echocardiography, and cardiac CTA. During the
operation, ICE, fluoroscopic image, and Carto three-dimensional mapping
system can be combined to guide catheter positioning better and adjust
catheter operation to ensure smooth operation and reduce operation time
and complications. Adequate preoperative evaluation, meticulous
intraoperative electrophysiological examination and mapping, and the use
of the latest assistive technologies are prerequisites for ensuring the
safe and effective operation of surgery, and each operator needs to take
it seriously.