Atrial isomerism is a form of heterotaxy, which is defined as an abnormal arrangement
of the internal thoracic-abdominal organs across the left-right axis of the body caused
by disruption of left-right axis orientation during early embryonic development. Cardiac
malformations are a major component of heterotaxy syndrome. Abnormal cardiac development
typically leads to atrial isomerism, resulting in either bilateral paired right atria
(right atrial isomerism) or paired left atria (left atrial isomerism; LAI).
Among the various kinds of congenital heart disease, atrial isomerism is rare. It
occurs in approximately 1 per 10,000 to 40,000 live births.
LAI results in 2 left sides with bilateral morphologic left atria (LA) and left atrial
appendages. Systemic venous abnormalities, such as interruption of the inferior vena
cava (IVC), occurs in 80% of patients with LAI, who have subsequent drainage of the
interrupted IVC into the azygos vein and, from there, to the atrium via the superior
vena cava (SVC).
In patients with LAI the sinus node may be either absent or hypoplasic.
As a result, patients with LAI are more susceptible to sinus node dysfunction (SND)
and atrial fibrillation (AF).
We now present a case report of pulmonary vein (PV) isolation to treat persistent
AF in a patient with LAI, SND, and interrupted IVC.
A 31-year-old male patient presented with palpitations and dyspnea on exercise in
February 2016. The patient had no significant past medical history and no family history
of heart diseases. He has never smoked, and he denied alcohol intake and use of recreational
drugs. The presenting electrocardiogram showed AF with ventricular heart rate around
85 beats per minute (bpm) and QRS duration 95 ms (Figure 1A). A 48-hour Holter showed
AF 100% of the time with average heart rate of 85 bpm (range, 48–231 bpm). An echocardiogram
showed normal size and function of the left and right ventricles; both atria with
normal size and structure; and no valvular disease. The patient initiated beta blocker
treatment for rate control and oral anticoagulation with apixaban. In April 2016 he
underwent electrical cardioversion. Postcardioversion electrocardiogram showed junctional
bradycardia that terminated into a low atrium rhythm at 75 bpm (Figure 1B). He remained
asymptomatic for several months, having AF recurrence with need of cardioversion in
May 2017 and February 2018. No antiarrhythmic drugs were attempted owing to a baseline
low atrium bradycardia. The most recent cardioversion was successful for 1 week. The
patient was very symptomatic while in AF and was scheduled for an AF ablation.
A: The presenting electrocardiogram (ECG) showed atrial fibrillation with heart rate
around 85 beats per minute (bpm), QRS 95 ms. B: Postcardioversion ECG showed junctional
rhythm that terminated into a low atrium rhythm at 75 bpm. C: A right anterior oblique
fluoroscopic projection showed a duodecapolar catheter positioned along the right
atrium and coronary sinus. The angiogram revealed the intracardiac echocardiography
(ICE) catheter and the long introducer to be outside the heart silhouette (black arrows).
D: A left anterior oblique fluoroscopic projection showed the ICE catheter and the
long introducer to be positioned posteriorly to the heart in the azygos vein.
A written informed consent was obtained for the procedure. The presenting rhythm was
AF. Access was obtained in the right femoral vein with ultrasound guidance using the
modified Seldinger technique. Three short sheaths were introduced into the vein (8F,
8.5F, and 8.5F). A 7F split duodecapolar catheter (Livewire Duo Deca, 60 mm split,
2-8-2 mm; Abbott, Lake Bluff, IL) was advanced into the heart and placed into the
coronary sinus. An 8F intracardiac echocardiography (ICE) catheter (Accuson Accunav;
Siemens, Erlangen, DE) was introduced up into the heart, but it was noted that there
was difficulty manipulating the catheter and visualizing heart structures. The short
8.5F short sheath was exchanged over a wire for an 8.5F long steerable sheath (Agilis
NST; Abbott). The sheath was placed in what was thought to be the mid-right atrium
and an angiogram was performed through the sheath. The angiogram showed an interrupted
IVC with a large azygos continuation into the SVC (Figure 1C and D). Owing to the
need for further anatomic evaluation prior to proceeding with the ablation, the procedure
A postprocedure chest magnetic resonance imaging showed both ventricles with normal
size and function. The right-sided atrium showed characteristics of a morphologically
LA. The bilateral subclavian, brachiocephalic, and SVC veins appeared to be widely
patent. A large azygos vein was seen draining into the SVC. There was an IVC interruption
with azygos continuation. The IVC was interrupted over 3 cm of the intrahepatic portion
and there was right-sided polysplenia (Figure 2).
Magnetic resonance imaging (MRI) showed an interruption of the inferior vena cava
over 3 cm of the intrahepatic portion with azygos continuation (arrow) and right-sided
polysplenia in a frontal plane (A) and in a sagittal plane (C). The MRI showed a large
azygos vein draining into the superior vena cava (arrow) in both the frontal plane
(B) and the sagittal plane (D).
With the diagnosis of LAI with interrupted IVC, the patient was scheduled for a new
AF ablation procedure via the right internal jugular (IJ) vein.
Transseptal access via internal jugular veins
A written informed consent was obtained. The procedure was performed under general
anesthesia. Firstly, 2 right femoral venous accesses were obtained using the modified
Seldinger technique. A 7F deflectable octapolar catheter (D-type curve; Biosense Webster,
Irvine, CA) was advanced from the right femoral vein through the azygos vein, SVC,
and right atrium and was placed in the right ventricle (RV). A 7F split duodecapolar
catheter (Livewire Duo Deca, 60 mm split, 2-8-2 mm; Abbott) was advanced from the
right femoral vein following the RV catheter and was placed into the coronary sinus.
A left IJ venous access was obtained to advance an 8F ICE catheter (Accuson Accunav;
Siemens) to the mid-RA (Figure 3A). Right IJ venous access was obtained using the
modified Seldinger technique and an 8.5F short sheath was introduced into the vein.
Transseptal catheterization was performed under fluoroscopic and ICE guidance. Heparin
bolus and continuous intravenous infusion were given prior transseptal puncture. The
sheath in the right IJ vein was exchanged over a wire for an 8.5F long steerable guiding
sheath (Torflex Supracross Superior Access Sheath; Baylis Medical, Montreal, Canada)
(Figure 3B). The long steerable sheath was advanced to the posterior portion of the
tricuspid annulus and was deflected, maintaining the relative position of the sheath
with the tip oriented in the 10 o’clock position from the operator’s view (leftward
and anterior). Next, the long sheath was gently manipulated with counterclockwise
rotation and was withdrawn approximately 2 cm, gradually changing the position of
the sheath with the tip oriented to the 8 o’clock position (leftward and posterior).
Once the long sheath reached the fossa ovalis, the deflection of the sheath was adjusted
until an adequate interatrial septum tenting was visualized on ICE (Figure 3C). The
transseptal access was performed using a radiofrequency needle (NRG; Baylis Medical).
The position of the long steerable sheath was maintained and the transseptal needle
was advanced until the sheath’s tip. Radiofrequency power was delivered at 10 watts.
Successful transseptal puncture was achieved at the first attempt, with no complications.
Once the transseptal access was obtained, the long steerable sheath was advanced over
the transseptal needle to the LA (Figure 3D and E). The transseptal needle was exchanged
for an 8F irrigated ablation catheter (ThermoCool RMT; Biosense Webster) and was positioned
in the LA (Figure 3F). The heparin infusion rate was adjusted to maintain an activated
clotting time between 350 and 400 seconds throughout the procedure.
A, B: Right anterior oblique (RAO) fluoroscopic images. A 7F deflectable octapolar
catheter was placed in the right ventricle (RV) from the right femoral vein through
the azygos vein, superior vena cava, and right atrium (RA) (blue arrow); a 7F duodecapolar
catheter was positioned along the RA and coronary sinus following the RV catheter
course (green arrow); and an 8F intracardiac echocardiography (ICE) catheter was positioned
in the mid-RA through the left internal jugular (IJ) vein (black arrow) (A). An 8.5F
long steerable guiding sheath (Torflex Supracross Superior Access Sheath; Baylis Medical,
Montreal, Canada) (red arrow) was positioned in the RA through the right IJ (B). C:
ICE image showing atrial septum tenting with the long steerable sheath in the fossa
ovalis previous to the transseptal access. D: ICE image: transseptal access was obtained
with a radiofrequency needle (NRG; Baylis Medical) and the long steerable sheath was
advanced into the left atrium (LA). E: RAO fluoroscopic image showing the long steerable
sheath (red arrow) advanced into the LA through the transseptal access from the right
IJ. F: RAO fluoroscopic image shows an 8F irrigated ablation catheter (ThermoCool
RMT; Biosense Webster, Irvine, CA) (red arrow) positioned in the right superior pulmonary
vein. G–J: Voltage map of the LA in the posteroanterior (G), anteroposterior (H),
RAO (I), and left anterior oblique (J) views showed no significant areas of scar.
Normal voltage range in atrial fibrillation was considered to be between 0.05 and
0.5 mV, shown in the right superior corner of each image. Bilateral radiofrequency
wide-area circumferential ablation lesions and carinal lines (red marks) were performed
to obtain isolation of all 4 pulmonary veins. An 8F irrigated ablation catheter (ThermoCool
RMT; Biosense Webster) and RMN system (Stereotaxis, St Louis, MO) were used for both
mapping and ablation.
The pulmonary veins and LA sites were mapped, making use of a 3D electroanatomic ablation
mapping system (Carto 3; Biosense Webster). Voltage above 0.5 mV was considered normal
owing to the presence of AF while mapping. Voltage less than 0.05 mV was representative
of scar tissue.
An 8F irrigated ablation catheter (ThermoCool RMT; Biosense Webster) was used to construct
a point-by-point map of the LA and PV. A robotic magnetic navigation (RMN) system
(Stereotaxis, St Louis, MO) was used for both mapping and ablation. A 312-point voltage
map of the LA using a fill threshold of 10 mm showed no significant areas of low voltage.
Ablation was performed using radiofrequency energy. Applications were delivered via
a generator (Stockert, Freiburg, Germany). Bilateral radiofrequency wide-area circumferential
ablation lesions and carinal lines were performed on the ostia of the PV. A routinely
high-power approach was used with a radiofrequency power set at 45 watts, independent
of the location in the LA. The irrigation flow was 17 mL/min. Esophageal temperature
was monitored continuously during the entire procedure. There were no difficulties
in moving the catheter during both mapping and ablation. Successful isolation of all
4 PV was obtained (Figure 3G–J).
Heart rhythm evaluation
After achieving PV isolation, external cardioversion at 200 joules terminated the
AF into a junctional bradycardia at 45 bpm. Atrial burst pacing showed an atrioventricular
node Wenckebach cycle length <350 ms. H-V interval was normal. Entrance and exit block
were demonstrated in all 4 PV. Rapid atrial burst pacing failed to induce any arrhythmia.
The patient remained in junctional rhythm after 45 minutes post ablation. A temporary
screw-in lead was placed in the RV through the right IJ for temporary pacing.
After a 24-hour period of observation, the patient remained in a low atrial rhythm
at 70 bpm alternating with some episodes of junctional bradycardia at 45 bpm. A permanent
dual-chamber pacemaker (Azure XT DR; Medtronic, Minneapolis, MN) was successfully
implanted through the left axillary vein 24 hours after the AF ablation. The pacemaker
settings were programmed in DDD mode at 50–130 bpm with the “Managed Ventricular Pacing”
feature, a paced A-V delay of 180 ms, and a sensed A-V delay of 150 ms.
After 6 months of follow-up the patient has been completely asymptomatic. The pacemaker
check showed no episodes of AF, 2.5% of atrial pacing, and no ventricular pacing needs.
Oral anticoagulation was stopped 3 months after the procedure.
Safety and adverse events
No complications occurred either at the access sites or secondary to the transseptal
access. The total radiation time for the AF ablation procedure was 33 minutes and
the radiation dose was 4476 μGy·m2.
We herein described a patient with LAI and SND presenting with symptomatic and persistent
AF. The incidence of AF in these patients has been reported to be around 10%. Moreover,
the rising prevalence of SND with age in these patients increases the risk of developing
AF. On the other hand, bradyarrhythmias are frequent and highly complex in LAI patients;
therefore the use of antiarrhythmic treatment alone is limited and catheter ablation
should be considered. However, the interruption of the IVC is highly frequent in LAI;
consequently, a standard transseptal approach via the femoral vein is not possible
in these patients.
The Supplementary Material section provides a discussion about transseptal access
from the right IJ, PV isolation with radiofrequency ablation and RMN, and SND management.
In summary, to the best of our knowledge, this is the first case report of the following:
(1) successful transseptal access via right IJ vein with a steerable sheath and a
radiofrequency needle in a patient with the combination of LAI, interrupted IVC, and
SND; and (2) successful PV isolation via right IJ vein using radiofrequency ablation
with RMN and no recurrence of AF after 6 months of follow-up.
Key Teaching Points
In patients with left atrial isomerism and interrupted inferior vena cava, successful
transseptal access can be obtained with a steerable sheath and a radiofrequency needle
through the right internal jugular vein.
Robotic magnetic navigation offers advantages for catheter manipulation for both mapping
and ablation within the left atrium in patients with interrupted vena cava with an
internal jugular vein approach.
When planning the procedural approach of pulmonary vein isolation, it is important
to consider that sinus node dysfunction is frequent in patients with left atrial isomerism.