International Journal of Arrhythmia 2013;14(1): 20-23.
Untitled Document
ECG & EP CASES
Successful Catheter Ablation of Atrial Tachycardia Using a Remote Magnetic Navigation System
Sung-Hwan Kim, MD Division of Cardiology, Department of Internal Medicine, Seoul St. Mary’s Hospital, Catholic University of Korea, Seoul, Korea
Introduction
Catheter ablation of supraventricular arrhythmias
has progressed since it was first introduced in the
1980s. Although advancements have been made in
mapping and imaging, conventional ablation methods
are still dependent on manual manipulation. Robotic catheter navigation is a cutting-edge technique for
ablation procedures.1,2 Robotic catheter manipulation
has the advantage of a more precise and unrestricted
catheter movement, enhancing procedural safety
and efficacy. Remote robotic catheter navigation
could reduce physical stress and radiation exposure
of physicians.3
Herein, we report our experience with focal atrial
tachycardia around the coronary sinus region. We
used the Niobe® system (MNS, Stereotaxis, USA) to
perform remotely controlled high-density 3-
dimensional electroanatomical CARTOTM (Biosense
Webster, USA) mapping and radiofrequency (RF)
ablation.
Case
A 28-year-old man presented with frequent
occurrence of premature atrial contraction and
atrial tachycardia, which had caused symptoms of
palpitations and dyspnea for 4 years (Figure 1).
Given the symptomatic and drug-refractory (betablockers
and flecainide) nature of the arrhythmia,
the patient was indicated for invasive electrophysiological
study and RF ablation. The ablation
procedure was performed under a conscious
sedative state induced with intravenous midazolam
and fentanyl. Intracardiac electrograms from the
high right atrium, His-bundle location, coronary
sinus, and right ventricular apex region were
simultaneously recorded and displayed using a surface electrocardiogram on a multichannel
recorder (Cardiolab, Prucka® Engineering, Houston,
TX, USA) (Figure 2).
During the electrophysiological
study, atrial tachycardia with a variable cycle
length (approximately 170-400 ms) was
spontaneously or easily induced by rapid right
atrial pacing. Atrial tachycardia was repeatedly
induced and terminated usually within 10 seconds.
The earliest atrial activation site was found at the
right atrial posterior wall (around the inferior part
of the crista terminalis). Mapping and ablation
around the right atrium were subsequently
performed using a 4-mm tip Navistar-RMT
catheter (Biosense Webster). Electroanatomical
mapping was performed using the CARTO-RMT
integration (Stereotaxis Inc.) system (Figure 3).
The electroanatomic activation mapping confirmed a
focal right atrial tachycardia originating from the
inferior part of the crista terminalis. Intracardiac
electrograms recorded at the earliest site were 42
ms before the inscription of surface P-waves.
Using magnetic navigation, RF ablation was
performed at this site. The Stockert RF generator
(Biosense Webster) was used to deliver RF in
a temperature-controlled mode (maximum
temperature, 50℃; power, 35 W). The RF ablation
of the lesion terminated the tachycardia.
Subsequently, several additional RF ablation
procedures were performed on contiguous lesions
circumferentially surrounding the successfully
ablated site. Atrial tachycardia could no longer be
induced. With an aggressive stimulation protocol
(decremental burst pacing up to 180 ms and up to 2
extrastimuli in both atria), only atrial fibrillation was induced, requiring intracardiac cardioversion.
The patient had remained symptom-free during
the 8-month follow-up period after the ablation.
Discussion
The magnetic navigation system can provide a
soft mapping catheter in conjunction with the
integrated 3-dimensional electroanatomical
mapping system.4 In addition, this allows gentle,
nontraumatic mapping, which may be advantageous
in focal arrhythmias such as atrial tachycardia.
Previous studies have demonstrated its application
in supraventricular and ventricular arrhythmias.
All cardiac chambers, including the coronary sinus
and epicardial space, have been successfully
accessed and mapped.
Most studies reported that the magnetic navigation system decreased X-ray exposure of the
operator.5 However, being remote from the patient
might have the risk of overlooking a potential
deterioration in clinical status. Careful nursing is
therefore mandatory. Our experience with remote
navigation was still preliminary, and a conclusion
with regard to long-term success could not be
drawn.
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