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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.

Successful Catheter Ablation ofAtrial Tachycardia Using a RemoteMagnetic Navigation System

Sung-Hwan Kim, MDDivision of Cardiology, Department of Internal Medicine, Seoul St. Mary’s Hospital, Catholic University of Korea, Seoul, Korea

Successful catheter ablation of atrial tachycardia using a remotemagnetic navigation system

ABSTRACTA 28-year-old man was admitted to our institution because of recurrent palpitation. He had had frequent

premature atrial contraction and atrial tachycardia for 4 years. His atrial tachycardia was refractory to

bisoprolol and flecainide; hence, he was referred for electrophysiological study and catheter ablation. Atrial

tachycardia was consistently induced spontaneously or with rapid atrial pacing. Intracardiac electrograms and

a 3-dimensional mapping system showed atrial tachycardia from the right atrial posterior wall. The earliest

atrial activation was found with a remote magnetic navigation system. Radiofrequency energy was applied at

the target region, successfully terminating the atrial tachycardia.

Key words: ■ arrhythmia ■ catheter ablation ■ remote navigation

Received: January 28, 2013Revision Received: March 25, 2013Accepted: March 30, 2013Correspondence: Sung-Hwan Kim, MD. Division of Cardiology,Department of Internal Medicine, Seoul St. Mary’s Hospital, College ofMedicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu,Seoul, KoreaTel: 82-2-2258-6071, Fax: 82-2-591-1506E-mail: sunghwan@catholic.ac.kr

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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 (beta-

blockers and flecainide) nature of the arrhythmia,

the patient was indicated for invasive electro-

physiological 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

Figure 1. Holter findings during the frequent premature atrial contractions.

A

B

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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

Figure 2. Intracardiac electrograms at the beginning of the atrial tachycardia.

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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.

References

1. Faddis MN, Blume W, Finney J, Hall A, Rauch J, Sell J, Bae KT,Talcott M, Lindsay B. Novel, magnetically guided catheter forendocardial mapping and radiofrequency catheter ablation.Circulation. 2002;106:2980-2985.

2. Ernst S, Ouyang F, Linder C, Hertting K, Stahl F, Chun J, HachiyaH, Bansch D, Antz M, Kuck KH. Initial experience with remotecatheter ablation using a novel magnetic navigation system:magnetic remote catheter ablation. Circulation. 2004;109:1472-1475.

3. Schwagten B, Witsenburg M, De Groot NM, Jordaens L, Szili-Torok T. Effect of magnetic navigation system on procedure timesand radiation risk in children undergoing catheter ablation. Am JCardiol. 2010;106:69-72.

4. Bauernfeind T, Akca F, Schwagten B, de Groot N, Van Belle Y,Valk S, Ujvari B, Jordaens L, Szili-Torok T. The magneticnavigation system allows safety and high efficacy for ablation ofarrhythmias. Europace. 2011;13:1015-1021.

5. Miyake CY, Mah DY, Atallah J, Oikle HP, Melgar ML, AlexanderME, Berul CI, Cecchin F, Walsh EP, Triedman JK. Nonfluoroscopicimaging systems reduce radiation exposure in childrenundergoing ablation of supraventricular tachycardia. HeartRhythm. 2011;8:519-525.

Figure 3. Three-dimensional reconstruction of the CARTO system. The red spot marks the ablation point.