Magnetic Catheter Research Articles

Initial clinical experience of remote magnetic navigation system for catheter mapping and ablation of supraventricular tachycardias

A remote magnetic navigation system (MNS) has been developed for mapping and catheter ablation of cardiac arrhythmias. The present study evaluates the safety and feasibility of this system to perform radiofrequency (RF) ablation in patients with supraventricular tachycardias (SVT). A total of 32 patients (22 female; mean age 44 +/- 16 years) with documented SVT underwent mapping and ablation using Helios II (a 4-mm-tip magnetic catheter), under the guidance of the MNS (Niobe II, Stereotaxis, Inc.). Catheter ablation procedure with MNS was successful in 30/32 (94%) patients including all patients (27/27, 100%) with atrioventricular nodal reentrant tachycardia (AVNRT) and three of five patients (60%) with atrioventricular reentrant tachycardia (AVRT) without any complication. The procedural successful rate in patients with AVNRT was significantly higher than those in patients with AVRT (P < 0.001). Overall, the medium number of RF application using the MNS was 2 (mean 2.7 +/- 1.6, range 1 to 7), and the medium numbers of RF for AVNRT and AVRT were 2 and 3, respectively. There was no significant difference in the mean procedural time between patients with AVNRT and AVRT (126.3 +/- 38.6 vs. 138.0 +/- 40.3 min, P = 0.54). However, the mean fluoroscopy time was significantly shorter in patients with AVNRT than those with AVRT (5.7 +/- 3.0 vs. 16.5 +/- 2.5 min, P < 0.001). Among those patients with AVNRT, the mean procedural time (139.3 +/- 45.0 vs. 112.3 +/- 24.9 min, P = 0.07) and fluoroscopic time (3.2 +/- 1.0 vs. 8.0 +/- 2.2 min, P < 0.001) were shorter for the later 13 patients than the first 14 patients, suggesting a learning curve in using the MNS for RF ablation. The Niobe MNS is a new technique that can allow safe and effective remote-controlled navigation and minimize the need for fluoroscopic guidance for ablation catheter of AVNRT. However, further improvement is required to achieve a higher successful rate for treatment of AVRT.

Magnetic Navigation and Catheter Ablation of Right Atrial Ectopic Tachycardia in the Presence of a Hemi‐Azygos Continuation: A Magnetic Navigation Case Using 3D Electroanatomical Mapping

We report on a 63-year-old female patient in whom an electrophysiologic study discovered a hemi-azygos continuation. Using the magnetic navigation system, remote-controlled ablation was performed in conjunction with the 3D electroanatomical mapping system. Failing the attempt to advance a diagnostic catheter from the femoral vein, a diagnostic catheter was advanced via the left subclavian vein into the coronary sinus. The soft magnetic catheter was positioned in the right atrium via the hemi-azygos vein, and 3D mapping demonstrated an ectopic atrial tachycardia. Successful ablation was performed entirely remote controlled. Fluoroscopy time was only 7.1 minutes, of which 45 seconds were required during remote navigation. Remote-controlled catheter ablation using magnetic navigation in conjunction with the electroanatomical mapping system proved to be a valuable tool to perform successful ablation in the presence of a hemi-azygos continuation.

Feasibility and Safety of Remote-Controlled Magnetic Navigation for Ablation of Atrial Fibrillation

Radiofrequency ablation for atrial fibrillation (AF) involves complex catheter manipulation resulting in prolonged procedure time and fluoroscopy exposure. Remote magnetic navigation (RMN) represents a novel approach toward improving the ability to perform complex ablation. Forty patients underwent ablation for AF, 20 using RMN (NIOBE II, Stereotaxis, Inc) with a 4-mm-tip magnetic catheter (Celsius, Biosense Webster) and 20 using a conventional 8-mm-tip bidirectional ablation catheter (Blazer, Boston Scientific). All patients underwent a combined wide area circumferential ablation and segmental pulmonary vein (PV) isolation using a circular mapping catheter and cavotricuspid isthmus ablation for right atrial flutter. The procedural end point was PV entrance block. There was no difference in atrial size, left ventricular systolic function, or type of AF between groups. PV entrance block was achieved in all patients. Mean procedure time was 279 +/- 60 minutes in the conventional group versus 209 +/- 56 minutes in the RMN group (p <0.001). Mean fluoroscopy time in the conventional group was 58.6 +/- 21 minutes versus 19.5 +/- 9.8 in the RMN group (p <0.001). At 1 year there were 15 patients in the conventional group and 16 in the RMN group free from clinical AF and off antiarrhythmic drugs (p = NS). There were 2 additional ablations performed for atypical atrial flutter in the conventional group and 3 in the RMN group (p = ns). Ablation catheter char formation was not observed. There were no procedural complications. In conclusion, radiofrequency ablation of AF performed with RMN is safe and feasible. Compared with conventional hand-navigated ablation, RMN ablation results in similar clinical outcomes with decreased fluoroscopy and procedure times.

Impact of Remote Magnetic Catheter Navigation on Ablation Fluoroscopy and Procedure Time

Remote magnetic catheter navigation (RCN) is gaining acceptance in clinical cardiac electrophysiology, but details regarding how RCN affects procedure execution are not well characterized. From January 1, 2005, to November 30, 2007, 721 cases were retrospectively analyzed and compared. Of these, 127 used RCN and 594 used manual catheter navigation (MCN). Data including procedure time, fluoroscopy time, ablation catheter, procedural success, and complications were extracted from our procedure database and compared between RCN and MCN. RCN use significantly decreased fluoroscopy time for atrial fibrillation (AF) ablation (-29 minutes, P < 0.001), atrioventricular nodal reentrant tachycardia ablation (-14 minutes, P < 0.001), and atrioventricular reentrant tachycardia ablation (-18 minutes, P = 0.045). While RCN significantly increased mean procedure time for AF (+36 minutes, P = 0.003) and atypical atrial flutter cases (+116 minutes, P = 0.016), RCN AF procedure time diminished with increasing number of cases performed. Two cases of tamponade occurred during AF ablation using MCN (2.2%, 2 of 91 cases). No tamponade occurred during all 75 AF ablations with RCN. RCN can reduce fluoroscopy time and may reduce complications during catheter ablation. While it may increase total procedure duration, procedure times decrease with increasing operator experience. (PACE 2008; 31:1399-1404).

Remote Magnetic Versus Manual Catheter Navigation for Ablation of Supraventricular Tachycardias: A Randomized, Multicenter Trial

The potential benefits of remote robotic navigation for catheter ablation procedures have not been demonstrated in controlled clinical trials. The purpose of this study was to compare remote magnetic catheter navigation to manual navigation for the ablation of common supraventricular arrhythmias. Patients with supraventricular arrhythmias due to atrioventricular (AV) nodal reentry, accessory pathways, or undergoing AV junctional ablation for complete heart block were randomized in a 3:1 ratio between magnetic (Niobe system and Helios II catheter, Stereotaxis, Inc., St. Louis, MO) and manual navigation for radiofrequency ablation at 13 centers. The primary endpoint of the study was total fluoroscopic time. Fifty-six patients were randomized to magnetic navigation and 15 to manual navigation. AV nodal reentry was the most common arrhythmia in both groups. Total fluoroscopy time was reduced in the magnetic navigation group (median 17.8 minutes, interquartile (IQ) range 9.9,27.8 minutes) compared to manual navigation (27.1, IQ 19.0,48.0, P < 0.05). The acute success rates (91% for magnetic and 87% for manual navigation, P > 0.05) did not differ between groups. The number of lesions delivered was less for magnetic navigation (6, IQ 4,9 vs 10, IQ 7, 26, P < 0.05). Total procedure time (median 151, IQ 111, 221 minutes magnetic and 151, IQ 110, 221 minutes manual) and complication rates (5.4% patients magnetic and 6.7% patients manual) were similar between the groups (both P > 0.05). Remote magnetic catheter navigation reduces fluoroscopic time and radiofrequency lesion deliveries for the ablation of common supraventricular arrhythmias compared to manual catheter navigation.

Initial clinical experience with a second-generation intravascular magnetic resonance imaging catheter for lipid assessment in coronary atherosclerotic plaques

stained (HE but at 14 days, staining was seen in 69% (bare) and 100% (polymer) of struts (NS). SMC actin was seen in N92% of struts at 30, 60, and 90 days (NS). Staining for L1 was greatest at 2 days; 65% of BMS and 41% of polymer struts had L1+ cells near the struts (NS). Based on morphology, most L1+ cells at 2 days were granulocytes. By 14 days, L1+ cells decreased (b10% of struts). No L1 staining was seen at 30, 60, or 90 days. Conclusion: No statistical difference in scores was seen in bare vs. Translute polymer-coated stents for inflammation, endothelialization, PCNA, or SMC actin at 2, 14, 30, 60, or 90 days, suggesting similar healing with no excess inflammation or adverse vascular effects related to Translute polymer.

Preclinical evaluation of a second generation intravascular magnetic resonance imaging catheter for lipid assessment in human atherosclerotic plaques

Objective: An intravascular magnetic imaging (IVMRI) system has been developed to assess the lipid content of atherosclerotic plaques. A secondgeneration 6-Fr compatible IVMRI catheter was designed with dual sensors for bidirectional measurement of lipid within 100 μm of the vessel lumen. We compared the IVMRI lipid fraction index (LFI—the normalized MR signal) to quantitative and gross histopathology assessments in a human ex vivo plaque model. Methods: Test samples consisted of 100 aortic lesions from 48 human cadavers. LFI was determined in each sample and results were correlated with histopathology. Samples were sectioned at 200-μm increments and stained with Oil Red O and Movat's Pentachrome. Normal smooth muscle cells, adaptive intimal thickening, and fibrous-rich lesions were identified as “nonlipidic,”while foam cells/lipid pool-rich lesions and necrotic cores were identified as “lipidic.” Results: Of the 59 lipidic lesions identified by histopathology, 49 were similarly identified by a LFI≥0.35. Fig. 1 shows the comparison of LFI level to the histology. Based on the prospectively defined LFI cutoff of 0.35, the sensitivity, specificity, and positive predictive values for distinguishing between “nonlipidic” and “lipidic” lesions were 83%, 88%, and 91%, respectively. Conclusions: The IVMRI LFI is an effective parameter for assessing the lipid content of the vessel wall. IVMRI may provide valuable information on plaque lipid characteristics for lesion assessment and risk profiling.

Recurrent Intraventricular Hemorrhages Caused by an AVM Detected by Angiography with Initially Normal Angiogram

Primary intraventricular haemorrhage (PIVH) is an uncommon type of non-traumatic cerebral haemorrhage limited to the ventricular system arising in adults and children, with diverse aetiology and variable course. Vascular malformations account for 34% of PIVH, whereas no cause is found in 21-47%. When a primary intraventricular haemorrhage is detected in a young patient an underlying lesion such as an arteriovenous malformation (AVM) must be ruled out. The diagnosis may be suspected when there is sudden onset of headache, nausea and vomiting with or without a reduced level of consciousness. Nevertheless, even if clinical features suggest the diagnosis of PIVH, cerebral computed tomography (CT) scan is required for confirmation, and magnetic resonance imaging (MRI) and catheter angiography are necessary to establish the aetiology. We describe a case of isolated recurrent intraventricular haemorrhages caused by AVM detected by diagnostic intracranial angiography with no abnormality demonstrated on angiography four years earlier.

Initial Clinical Experience with a Remote Magnetic Catheter Navigation System for Ablation of Cavotricuspid Isthmus‐Dependent Right Atrial Flutter

A remote magnetic navigation system (MNS) is available and has been used with a 4-mm-tip magnetic catheter for radiofrequency (RF) ablation of some supraventricular and ventricular arrhythmias; however, it has not been evaluated for the ablation of cavotricuspid isthmus-dependent right atrial flutter (AFL). The present study evaluates the feasibility and efficiency of this system and the newly available 8-mm-tip magnetic catheter to perform RF ablation in patients with AFL. Twenty-six consecutive patients (23 men, mean age 64.6 +/- 9.6 years) underwent RF ablation using a remote MNS. RF ablation was performed with an 8-mm-tip magnetic catheter (70 degrees C, maximum power 70 W, 90 seconds). The endpoint of ablation was complete bidirectional isthmus block. To assess a possible learning curve, procedural data were compared between the first 14 (group 1) and the rest (group 2) of the patients. The initial rhythm during ablation was AFL in 20 (19 counterclockwise and 1 clockwise) and sinus rhythm in six patients. Due to technical issues, the ablation in the 18th patient could not be done with the MNS, and so we switched to conventional ablation. The remote magnetic navigation and ablation procedure was successful in 24 of the 25 (96%) remaining patients with AFL. In one patient (patient 2), conventional catheter was used to complete the isthmus block after termination of AFL. The procedure, preparation, ablation, and fluoroscopy times (median [range]) were 53 (30-130) minutes, 28 (10-65) minutes, 25 (12-78) minutes, and 7.5 (3.2-20.8) minutes, respectively. Patients in group 2 had shorter procedure (45 [30-70] min vs 80 [57-130] min, P = 0.0001), preparation (25 [10-30] min vs 42 [30-65] min, P = 0.0001), ablation (20 [12-40] min vs 31 [20-78] min, P = 0.002), and fluoroscopy (7.2 [3.2-12.2] min vs 11.0 [5.4-20.8] min, P = 0.014) times. No complication occurred during the procedure. Using a remote MNS and an 8-mm-tip magnetic catheter, ablation of AFL is feasible, safe, and effective. Our data suggest that there is a short learning curve for this procedure.

Initial Experience with a Novel Remote‐Guided Magnetic Catheter Navigation System for Left Ventricular Scar Mapping and Ablation in a Porcine Model of Healed Myocardial Infarction

This study examined the feasibility of using a remote magnetic catheter navigation system (MNS) in concert with an EAM system to perform detailed left ventricular scar mapping and ablation in a porcine model of healed myocardial infarction. Substrate-based catheter ablation of ventricular tachycardia (VT) involves detailed electroanatomical mapping (EAM) of the ventricles. While a safe and effective procedure, VT ablation is nonetheless uncommonly performed, due in part to the technical challenges related to ventricular mapping. Using a prototype EAM system (CARTO-RMT), seven chronically infarcted swine were mapped using either: (i) a standard manually manipulated catheter or (ii) a magnetic remotely manipulated (Niobe) catheter. A total of 191 +/- 54 and 221 +/- 64 points were acquired to map the chamber either manually or remotely, respectively. Procedure times were longer remotely (94 +/- 22 vs. 59 +/- 19 minute, P = 0.004; and 27 +/- 8 vs. 18 +/- 3 sec/point, P = 0.04), but this became less apparent with increased operator experience. However, the fluoroscopy time was significantly shorter with remote mapping (56 +/- 56 vs. 244 +/- 67 sec/map, P = 0.03). The calculated scar size was comparable between the two methods (16.3 +/- 4.9 vs. 16.4 +/- 4.8 cm2, P = 0.37). Pathologic examination confirmed that the MNS was able to precisely deliver radiofrequency lesions to the scar borders. Using the MNS, the error to reach an evenly distributed set of endocardial targets was 6.6 +/- 3.6 mm and 4.6 +/- 2.0 mm, using transseptal and retrograde approaches, respectively. Ventricular mapping using this remote navigation paradigm is technically possible and requires minimal fluoroscopy exposure, potentially facilitating ventricular substrate mapping and ablation.

Remote Magnetic Catheter Mapping and Ablation of Permanent Junctional Reciprocating Tachycardia in a Seven‐Year‐Old Child

Mapping and catheter ablation of permanent junctional reciprocating tachycardia (PJRT) in children can be challenging. Remote magnetic navigation may improve precise mapping and catheter stability during ablation, as well as reduce fluoroscopy time, especially in conjunction with a non-fluoroscopic mapping system. We report a case of PJRT ablation in a 7-year-old child using remote magnetic navigation. Mapping of the right atrium (RA) and the coronary sinus (CS) and catheter ablation were performed using remote magnetic navigation in conjunction with a non-fluoroscopic mapping system (NavX). We observed excellent catheter steering abilities and constant wall contact during ablation, allowing a short and safe procedure. Remote magnetic navigation may be used for mapping and ablation of PJRT in children.

Remote Navigation and Ablation of Atrial Fibrillation

We have developed a new approach based on remote navigation and ablation by a magnetic catheter in a large number of patients with paroxysmal, persistent, or permanent atrial fibrillation. The operator sits in a separate control room, away from the X‐ray beam and the patient's body. A 4 mm magnetic catheter is integrated with a newly developed electroanatomical mapping system. The catheter is moved by a joystick that allows to and fro movement inside the left atrium. Magnetic field vectors for each navigation target are stored and, if necessary, they are reapplied at any time while the magnetic catheter is navigated automatically. Remote circumferential pulmonary vein ablation is performed with a target temperature of 65°C and a power limit of 50 W. Navigation and ablation targets can be safely and successfully achieved in all patients in a relatively short period of time (usually in less than one hour). The manual approach is totally operator‐dependent, while the remote one is not, but it mostly depends on a well‐trained team. When combined with an accurate electroanatomical mapping system this remote technology allows not only to optimize contact and stability with tissue, but also to enable movement between preassigned intracardiac points automatically, either avoiding intervening tissue structures or moving at a defined rate across the surface of the intervening tissue. Finally, there is a significant shortening of radiation exposure time, relevant both for the unprotected patient and the operator.

“Sequential” Mapping Mimicking “Simultaneous” Mapping Using Magnetic Navigation During Catheter Ablation of Supraventricular Tachycardia: Results of the Single DX Study

Introduction: The magnetic navigation system (MNS) allows remote‐controlled navigation of an ablation catheter from the control room. We tested the hypothesis, whether the MNS and a single additional diagnostic nonsteerable catheter would have the potential to identify the tachycardia substrate and allow subsequent ablation in patients with documented supraventricular tachycardia (SVT). Methods and Results: A total of 41 patients (24 females, age 45 ± 16 years) underwent an invasive electrophysiologic (EP) study using the MNS. Together with a conventional diagnostic catheter in the right ventricle, the magnetic catheter (MC) was used to investigate the underlying EP substrate in a sequential fashion and subsequently to perform radiofrequency (RF) ablation. A custom‐made device allowed the separate assessment of fluoroscopy deployed from the control and examination room. Using conventional EP criteria, identification of the underlying substrate was possible in all but 4 noninducible patients (no accessory pathway [AP], no dual atrioventricular [AV] node): APs were present in 10 patients, AV node re‐entrant tachycardia in 26 patients, and ectopic atrial tachycardia in 1 patient. Despite 3 patients, in which switching to conventional ablation was necessary (8%), all others were successfully treated using the MNS. Overall fluoroscopy amounted to a median of 3.4 minutes (interquartile range, 2.4–5.3) with only a median of 1.0 minute exposure for the investigator. Conclusions: Remote catheter ablation of SVT using the new MNS Niobe and a single conventional diagnostic catheter is feasible. Compared to conventional EP studies, a reduction of radiation exposure for both patients and investigators was demonstrated.

Successful ablation of a concealed parahisian accessory pathway using a remote magnetic navigation system following failure by conventional methods

Using conventional catheters, ablation of concealed parahisian accessory pathways may be difficult and high risk for heart block. We describe the case of a concealed parahisian accessory pathway with three prior attempts to ablate using conventional methods (RF and cryotherapy). Using a remote magnetic navigation system, successful ablation occurred following a single RF lesion (total fluoroscopy time 17 min). In contrast to previous attempts, the patient remained asymptomatic during follow-up (12 months). This is the first report of successful remote magnetic catheter ablation of a concealed parahisian AP. Magnetic catheter stability during RF application likely contributed to the success of this procedure and may have minimized the risk of AV block.

P1-56: Magnetic catheter navigation is safe and effective for ablation of supraventricular tachycarida: Results of the multi-center ATTRAC study

P1-56: Magnetic catheter navigation is safe and effective for ablation of supraventricular tachycarida: Results of the multi-center ATTRAC study

Robotic Magnetic Navigation for Atrial Fibrillation Ablation

We assessed feasibility of magnetic catheter guidance in patients with atrial fibrillation (AF) undergoing circumferential pulmonary vein ablation (CPVA). No data are available on feasibility of remote navigation for AF ablation. Forty patients underwent CPVA for symptomatic AF using the NIOBE II remote magnetic system (Stereotaxis Inc., St. Louis, Missouri). Ablation was performed with a 4-mm tip, magnetic catheter (65 degrees C, maximum 50 W, 15 s). The catheter tip was guided by a uniform magnetic field (0.08-T), and a motor drive (Cardiodrive unit, Stereotaxis Inc.). Left atrium maps were created using an integrated CARTO RMT system (Stereotaxis Inc.). End point of ablation was voltage abatement >90% of bipolar electrogram amplitude. Remote ablation was successful in 38 of 40 patients without complications. The median mapping and ablation time was 152.5 min (range, 90 to 380 min) but was much longer in the first 12 patients (192.5 min vs. 148 min; p = 0.012). Median ablation time was 49.5 min (range, 17 to 154 min), but it was much shorter in the last 28 patients than in the first 12 patients (49 min vs. 70 min; p = 0.021). Patients receiving remote ablation had longer procedure times than control patients (p < 0.001) with similar mapping time but shorter ablation time on right-sided pulmonary veins. Many more mapping points regardless of their location were collected remotely (p < 0.001). Remote magnetic navigation for AF ablation is safe and feasible with a short learning curve. Although all procedures were performed by a highly experienced operator, remote AF ablation can be performed even by less experienced operators.

Remote magnetic navigation for mapping and ablating right ventricular outflow tract tachycardia

Navigation, mapping, and ablation in the right ventricular outflow tract (RVOT) can be difficult. Catheter navigation using external magnetic fields may allow more accurate mapping and ablation. The purpose of this study was to assess the feasibility of RVOT tachycardia ablation using remote magnetic navigation. Mapping and ablation were performed in eight patients with outflow tract ventricular arrhythmias. Tachycardia mapping was undertaken with a 64-polar basket catheter, followed by remote activation and pace-mapping using a magnetically enabled catheter. The area of interest was localized on the basket catheter in seven patients in whom an RVOT arrhythmia was identified. Remote navigation of the magnetic catheter to this area was followed by pace-mapping. Ablation was performed at the site of perfect pace-mapping, with earliest activation if possible. Acute success was achieved in all patients (median four applications). Median procedural time was 144 minutes, with 13.4 minutes of patient fluoroscopy time and 3.8 minutes of physician fluoroscopy time. No complications occurred. One recurrence occurred during follow-up (mean 366 days). RVOT tachycardias can be mapped and ablated using remote magnetic navigation, initially guided by a basket catheter. Precise activation and pace-mapping are possible. Remote magnetic navigation permitted low fluoroscopy exposure for the physician. Long-term results are promising.

Remote controlled magnetically guided pulmonary vein isolation in canines

Ablation of atrial fibrillation (AF) remains a challenging procedure fraught with significant risks and technical difficulties. A magnetically guided catheter system has been developed that potentially addresses many of these challenges. Fully remote controlled electrical isolation of pulmonary veins was performed in canines, facilitated by a three-dimensional computed tomogram (CT) that depicted the anatomic relationships of the pulmonary veins and the left atrium. The purpose of this study was to evaluate the feasibility of pulmonary vein isolation with a novel remote controlled magnetically guided catheter. CT scans were obtained in seven healthy male canines. A 7-Fr irrigated magnetic catheter was advanced transseptally to the left atrium. A magnetic guidance system was used to control the orientation of the catheter tip. A mechanical device advanced or retracted the catheter as needed. Pulmonary venography was performed and compared with the CT scan. The CT scan was used as a visual reference to set the magnetic field vectors. Radiofrequency energy was delivered through the irrigated magnetic catheter to isolate the superior pulmonary veins, as judged by elimination of pulmonary vein potentials. The isolation procedure was successful in all 14 pulmonary veins, and there was no evidence of stenosis at 80-100 days postprocedure. These results demonstrate that remote controlled catheter ablation is safe and effective for segmental pulmonary vein isolation. This technology could facilitate curative ablation of AF in humans and reduce the occupational hazards to the operator of prolonged procedures and radiation exposure.

Pre-clinical canine testing of 3D electroanatomical mapping system developed for a robotic catheter maneuvering system for left atrial mapping

The purpose was to test in dogs a new 3D electroanatomical mapping system (CARTO-RMT, Biosense Webster) developed for use with a robotic magnetic catheter maneuvering system (MMS) (Niobe, Stereotaxis-Siemens) in mapping and ablation of the left atrium (LA) and pulmonary veins (PV). MMS uses 2 computer controlled magnets to generate a magnetic field (MF) in any direction. The MF directs a flexible catheter with a small magnet in the tip, while a screw-drive device advances/withdraws the catheter.

Catheter ablation of supraventricular tachycardias using the remote navigation system Niobe

The magnetic navigation system (MNS) Niobe (Stereotaxis Inc, USA) allows remote-controlled navigation by changing the orientation of a small magnet imbedded in the tip of an ablation catheter by two outer permanent magnets (0.08 Tesla). In addition, using a motor unit (Cardiodrive, Stereotaxis) advancement and retraction of the magnetic catheter can be performed from the control room without radiation exposure for the investigator.