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

Robotic magnetic-guided catheter ablation in patients with congenital heart disease: a systematic review and pooled analysis

BACKGROUND

Robotic magnetic navigation (RMN) has emerged as a potential solution to overcome challenges associated with catheter ablation of arrhythmias in patients with congenital heart disease (CHD).

OBJECTIVES

To assess safety and efficacy of RMNguided catheter ablation in patients with CHD.

DESIGN AND METHODS

A systematic review and pooled analysis was conducted on patients with CHD who underwent RMNguided catheter ablation. Random effects models were used to generate pooled estimates with the inverse variance method used for weighting studies.

RESULTS

Twentyfour nonoverlapping records included 167 patients with CHD, mean age 36.5 years, 44.6% female. Type of CHD was simple in 27 (16.2%), moderate in 32 (19.2%), and complex in 106 (63.5%). A total of 202 procedures targeted 260 arrhythmias, the most common being macroreentrant atrial circuits. The mean procedural duration was 207.5 minutes, with a mean fluoroscopy time of 12.1 minutes. The pooled acute success rate was 89.2% [95% CI (77.8%, 97.4%)]. Freedom from arrhythmia recurrence was 84.5% [95% CI (72.5%, 94.0%)] over a mean follow-up of 24.3 months. The procedural complication rate was 3.5% with no complication attributable to RMN technology.

CONCLUSION

RMN-guided ablation appears to be safe and effective across a variety of arrhythmia substrates and types of CHD.

Quality of life and symptoms in patients selected for ablation of ventricular extrasystoles: a prospective study

PURPOSE

Evaluation of the impact of catheter ablation for ventricular extrasystoles (VES) in structurally normal hearts on quality of life (QOL) and symptomatology.

METHODS

Symptom analysis assessed with a disease-specific questionnaire, EHRA score for AF, and QOL analysis at baseline and 1 year after ablation.

RESULTS

The study enrolled 39 patients between April 2016 and November 2019. Two patients were excluded from further analysis. At baseline, palpitations were reported in 31/37 (84%); syncope in 12/37 (32%); other cardiac symptoms in 33/37 (89%) of patients. The EHRA score was 3 or 4 in 13 patients (35%). With the modified arrhythmia-specific questionnaire (MASQ) psychological and physical scores were 46 and 39%. The overall perception of health in the SF-36 was 56 ± 16%. Ablation was performed in 35/37 (95%). At regular follow-up, symptoms were reported in 14/37 (38%) patients. ECG suggested a good procedural outcome in 65% with VES burden on Holter < 1% in 68%. At follow-up, palpitations were reported in 61% (P < 0.07); syncope in only 1 patient (P < 0.05). The EHRA score was 3 or 4 in only one patient (P < 0.05). MASQ scores improved to 62 and 60% (both p < 0.001). The overall perception of health in the SF-36 became 64 ± 17% (P < 0.02).

CONCLUSIONS

Patients with VES suffer from a wide variety of symptoms and have a low quality of life, as demonstrated by the EHRA score and conventional questionnaires. After catheter ablation, palpitations are still reported, but become less frequently present. Syncope becomes rare. Quality of life improves significantly from all perspectives.

Remote Magnetic Navigation: A Focus on Catheter Ablation of Ventricular Arrhythmias

VT ablation is based on percutaneous catheter insertion under fluoroscopic guidance to selectively destroy (i.e., ablate) myocardial tissue regions responsible for the initiation or propagation of ventricular arrhythmias. Although the last decade has witnessed a rapid evolution of ablation equipment and techniques, the control over catheter movement during manual ablation has remained largely unchanged. Moreover, the procedures are long, and require ergonomically unfavorable positions, which can lead to operator fatigue. In an attempt to overcome these constraints, several technical advancements, including remote magnetic navigation (RMN), have been developed. RMN utilizes a magnetic field to remotely manipulate specially designed soft-tip ablation catheters anywhere in the x, y, or z plane inside the patient's chest. RMN also facilitates titration of the contact force between the catheter and the myocardial tissue, which may reduce the risk of complications while ensuring adequate lesion formation. There are several non-randomized studies showing that RMN has similar efficacy to manual ablation, while complication rates and total radiation exposure appears to be lower. Although these data are promising, larger randomized studies are needed to prove that RMN is superior to manual ablation of VT.

Remote Navigation for Complex Arrhythmia

Magnetic navigation has been established as an alternative to conventional, manual catheter navigation for invasive electrophysiology interventions about a decade ago. Besides the obvious advantage of radiation protection for the operator who is positioned remotely from the patient, there are additional benefits of steering the tip of a very floppy catheter. This manuscript reviews the published evidence from simple arrhythmias in patients with normal cardiac anatomy to the most complex congenital heart disease. This progress was made possible by the introduction of improved catheters and most importantly irrigated-tip electrodes.

Feasibility of remote magnetic navigation for epicardial ablation

Percutaneous epicardial mapping and ablation is an emerging method to treat ventricular tachycardias (VT), premature ventricular complexes (PVC), and accessory pathways. The use of a remote magnetic navigation system (MNS) could enhance precision and maintain safety. This multiple case history demonstrates the feasibility and safety of the MNS-guided epicardial approach in mapping and ablation of ischaemic VT, outflow tract PVCs, and a left-sided accessory pathway. All patients had previously undergone endocardial mapping for the same arrhythmia. MNS could present an advantage from more precise navigation for mapping and maintaining catheter stability during energy application.

Remote magnetic navigation in atrial fibrillation

Atrial fibrillation (AF) is of profound public health importance and is largely a disease of aging and is responsible for increased morbidity- and mortality-related healthcare expenditures. Catheter ablation to isolate the pulmonary veins has become the therapy of choice for treatment of drug-refractory AF. Procedures can be very challenging and multiple difficulties must be overcome in order to achieve a successful outcome. The magnetic navigation system (MNS) has advantages in catheter maneuverability, stability and reproducibility. Due to the catheter design safety and efficacy of AF, ablation has increased. New developments are being made to allow fully remote ablation procedures in combination with the MNS. However, new technologies are still necessary to improve MNS ablation for AF.

Clinical characteristics and acute results of catheter ablation for outflow tract ventricular tachycardia or premature beats

PURPOSE

Contemporary outcome data of catheter ablation for outflow tract tachycardia (OTT) and ventricular premature beats (VPBs) are rare. The aim of this study was to describe the clinical characteristics, the acute procedure success rate, and the long-term survival of patients who underwent an ablation procedure for OTT or VPBs.

METHODS

The study was a single-center retrospective cohort study. All 82 consecutive OTT and VPB first ablation procedures between 1999 and 2009 were included. Patients with structural heart disease were excluded.

RESULTS

Mean age was 46 ± 13 years. Forty-three percent of the patients were male. All patients were alive after a median follow-up duration of 31 months (interquartile range, 14-65 months). Eighty-nine percent suffered from palpitations and 12 % had a history of syncope. Ventricular tachycardia was documented in 73 % and monomorphic VPBs in 99 %. Seventy-three percent of the patients were ablated in the right ventricular outflow tract, 15 % in the left ventricular outflow tract, and 12 % in the coronary cusps. Radiofrequency energy was used in 95 % of the patients, cryo energy in 9 %. Acute success was achieved in 78 %. Six patients (7 %) experienced a complication (five pericardial effusions, one pseudo-aneurysm of the femoral artery). Three patients needed pericardiocentesis (4 %).

CONCLUSION

Ablation for OTT and VPB is successful in the vast majority of cases, with a low but still existing complication rate. Long-term survival was excellent, underscoring the benign nature of this arrhythmia.

Acute and long-term outcomes of catheter ablation using remote magnetic navigation in patients with congenital heart disease

The aim of the present study was to assess the feasibility, safety, and long-term results of remote magnetic navigation in arrhythmias associated with complex congenital heart disease (CHD). The improved outcomes for CHD resulted in an increased number of complex arrhythmias requiring distinctive ablation techniques. Thirty-six patients with CHD (age 35 ± 19 years, 21 male) were divided into 3 complexity groups and underwent 43 radiofrequency catheter ablation procedures using the magnetic navigation system (including 7 redo ablations) in combination with the CARTO RMT system. A total of 59 tachyarrhythmias were identified. Most patients had surgical scar-related tachycardia (25 focal, including 4 microreentrant atrial tachycardia, and 27 macroreentrant atrial tachycardia). Four accessory pathways and three ventricular tachycardias were diagnosed and treated. In 31 patients, ablation was successful, with an end point of noninducibility (86%). The success rate for CHD complexity of type I, II, and III was 50%, 88%, and 89%, respectively. The mean procedure and fluoroscopy time was 216 ± 101 minutes and 40 ± 34 minutes, respectively. The number of radiofrequency applications was 42 ± 47. No major complications related to the procedures occurred. Of the patients, 67% remained free of recurrence during a mean follow-up of 26 ± 4 months. Recurrence developed in 0%, 16%, and 45% of patients with CHD type I, II, and III, respectively. In conclusion, the magnetic navigation system is feasible to treat arrhythmias with reasonable success rates and good long-term outcomes in adult patients with CHD. The use of the magnetic navigation system offers advantages in complex anatomic situations.

Biophysics and clinical utility of irrigated-tip radiofrequency catheter ablation

Catheter ablation by radiofrequency (RF) energy has successfully eliminated cardiac tachyarrhythmias. RF ablation lesions are created by thermal energy. Electrode catheters with 4-mm-tips have been adequate to ablate arrhythmias located near the endocardium; however, the 4-mm-tip electrode does not readily ablate deeper tachyarrhythmia substrate. With 8- and 10-mm-tip RF electrodes, ablation lesions were larger; yet, these catheters are associated with increased risk for coagulum, char and thrombus formation, as well as myocardial steam rupture. Cooled-tip catheter technology was designed to cool the electrode tip, prevent excessive temperatures at the electrode tip-tissue interface, and thus allow continued delivery of RF current into the surrounding tissue. This ablation system creates larger and deeper ablation lesions and minimizes steam pops and thrombus formation. The purpose of this article is to review cooled-tip RF ablation biophysics and outcomes of clinical studies as well as to discuss future technological improvements.

Safety and efficacy of the remote magnetic navigation for ablation of ventricular tachycardias--a systematic review

Objective

Remote magnetic navigation (RMN) is considered to be a solution for mapping and ablation of several arrhythmias. In this systematic review we aimed to assess the safety and efficacy of RMN in ablation of ventricular tachycardia (VT).

Methods

The National Library of Medicine’s PubMed database was searched for articles containing any of a predetermined set of search terms that were published prior to November 1, 2011. Quality of evidence was rated using the GRADE system.

Results

The database search resulted in 11 relevant articles evaluating the usefulness of RMN. Three groups of VTs were studied: VT in patients with ischemic cardiomyopathy (ICMP), non-ischemic cardiomyopathy (NICMP) and structurally normal hearts (SNH). The use of RMN in patients with ICMP has been associated with success rates ranging from 71 to 80%. RMN has been shown to be a feasible and effective method for ablation of VT in NICMP and SNH patients. Success rates between 50% and 100% have been reported in NICMP populations. Rates ranging from 86% to 100% have been reported for SNH patients. The lowest rates of arrhythmia recurrence are reported for SNH patients (0–17%). In ICMP and NICMP, recurrence rates of 0–30% and 14–50%, respectively, have been reported. One patient experienced total heart block, and one patient experienced a thromboembolic event after RMN catheter ablation procedures.

Conclusions

RMN has been shown to be an effective and safe method for ablation of VT in various patient populations with low recurrence and complication rates. However, more comparative and randomized studies are necessary, and therefore the true value of RMN for VT ablation remains still unknown.

Role of catheter ablation of ventricular tachycardia associated with structural heart disease

In patients with structural heart disease, ventricular tachycardia (VT) worsens the clinical condition and may severely affect the short- and long-term prognosis. Several therapeutic options can be considered for the management of this arrhythmia. Among others, catheter ablation, a closed-chest therapy, can prevent arrhythmia recurrences by abolishing the arrhythmogenic substrate. Over the last two decades, different techniques have been developed for an effective approach to both tolerated and untolerated VTs. The clinical outcome of patients undergoing ablation has been evaluated in multiple studies. This editorial gives an overview of the role, methodology, clinical outcome and innovative approaches in catheter ablation of VT.

Ablation of idiopathic ventricular tachycardia

Idiopathic ventricular arrhythmias occur in patients without structural heart disease. They can arise from a variety of specific areas within both ventricles and in the supravalvular regions of the great arteries. Two main groups need to be differentiated: arrhythmias from the outflow tract (OT) region and idiopathic left ventricular, so-called fascicular, tachycardias (ILVTs). OT tachycardia typically originates in the right ventricular OT, but may also occur in the left ventricular OT, particularly in the sinuses of Valsalva or the anterior epicardium or the great cardiac vein. Activation mapping or pace mapping for the OT regions and mapping of diastolic potentials in ILVTs are the mapping techniques that are typically used. The ablation of idiopathic ventricular arrhythmias is highly successful, associated with only rare complications. Newly recognized entities of idiopathic ventricular tachycardias are those originating in the papillary muscles and in the atrioventricular annular regions.

Comparison of magnetic navigation system and conventional method in catheter ablation of atrial fibrillation: is magnetic navigation system is more effective and safer than conventional method?

BACKGROUND AND OBJECTIVES

Although there have been so many reports of catheter ablation of atrial fibrillation (AF) with magnetic navigation system (MNS), it is not necessarily obvious that MNS is more effective than conventional ablation. We performed AF ablation with MNS and compared the clinical outcomes and radiofrequency ablation parameters with those of conventional ablation.

SUBJECTS AND METHODS

One hundred eleven consecutive patients (conventional group, n=70 vs. MNS group, n=41) undergoing catheter ablation of AF were enrolled. We compared and analyzed the procedural parameters, namely fluoroscopic time, procedural time, acute procedural success and 3 months success rate of both groups.

RESULTS

The MNS group was associated with slightly larger left atrial size (43.7±6.3 mm vs. 41.2±6.3 mm, p=0.04), significantly longer total procedure time (352±50 minutes vs. 283±75 minutes, p<0.0001), and shorter total fluoroscopic time (99±28 minutes vs. 238±45 minutes, p<0.0001) than the conventional group. The MNS and conventional group did not differ with respect to acute procedural success, AF recurrence, atrial flutter/atrial tachycardia recurrence, or total arrhythmia recurrence. While no complications were observed in the MNS group, eight cases of significant pericardial effusion occurred in the conventional group.

CONCLUSION

The MNS system seems to be effective and safe in the catheter ablation of AF, particularly in the population of patients with persistent AF and slightly dilated left atria.

The magnetic navigation system allows safety and high efficacy for ablation of arrhythmias

Aims

We aimed to evaluate the safety and long-term efficacy of the magnetic navigation system (MNS) in a large number of patients. The MNS has the potential for improving safety and efficacy based on atraumatic catheter design and superior navigation capabilities.

Methods and results

In this study, 610 consecutive patients underwent ablation. Patients were divided into two age- and sex-matched groups. Ablations were performed either using MNS (group MNS, 292) or conventional manual ablation [group manual navigation (MAN), 318]. The following parameters were analysed: acute success rate, fluoroscopy time, procedure time, complications [major: pericardial tamponade, permanent atrioventricular (AV) block, major bleeding, and death; minor: minor bleeding and temporary AV block]. Recurrence rate was assessed during follow-up (15 ± 9.5 months). Subgroup analysis was performed for the following groups: atrial fibrillation, isthmus dependent and atypical atrial flutter, atrial tachycardia, AV nodal re-entrant tachycardia, circus movement tachycardia, and ventricular tachycardia (VT). Magnetic navigation system was associated with less major complications (0.34 vs. 3.2%, P = 0.01). The total numbers of complications were lower in group MNS (4.5 vs. 10%, P = 0.005). Magnetic navigation system was equally effective as MAN in acute success rate for overall groups (92 vs. 94%, P = ns). Magnetic navigation system was more successful for VTs (93 vs. 72%, P < 0.05). Less fluoroscopy was used in group MNS (30 ± 20 vs. 35 ± 25 min, P < 0.01). There were no differences in procedure times and recurrence rates for the overall groups (168 ± 67 vs. 159 ± 75 min, P = ns; 14 vs. 11%, P = ns; respectively).

Conclusions

Our data suggest that the use of MNS improves safety without compromising efficiency of ablations. Magnetic navigation system is more effective than manual ablation for VTs.

[Magnetic navigation for ablation of cardiac arrhythmias]

BACKGROUND

The first use of magnetic navigation for radiofrequency ablation of supraventricular tachycardias, was published in 2004. Subsequently, the method has been used for treatment of most types of tachyarrhythmias. This paper provides an overview of the method, with special emphasis on usefulness of a new remote-controlled magnetic navigation system.

MATERIAL AND METHODS

The paper is based on our own scientific experience and literature identified through a non-systematic search in PubMed.

RESULTS

The magnetic navigation system consists of two external electromagnets (to be placed on opposite sides of the patient), which guide an ablation catheter (with a small magnet at the tip of the catheter) to the target area in the heart. The accuracy of this procedure is higher than that with manual navigation. Personnel can be quickly trained to use remote magnetic navigation, but the procedure itself is time-consuming, particularly for patients with atrial fibrillation. The major advantage is a considerably lower radiation burden to both patient and operator, in some studies more than 50 %, and a corresponding reduction in physical strain on the operator. The incidence of procedure-related complications seems to be lower than that observed with use of manually operated ablation catheters. Work is ongoing to improve magnetic ablation catheters and methods that can simplify mapping procedures and improve efficacy of arrhythmia ablation. The basic cost for installing a complete magnetic navigation laboratory may be three times that of a conventional electrophysiological laboratory.

INTERPRETATION

The new magnetic navigation system has proved to be applicable during ablation for a variety of tachyarrhythmias, but is still under development.

Endo-epicardial ablation of ventricular arrhythmias in the left ventricle with the Remote Magnetic Navigation System and the 3.5-mm open irrigated magnetic catheter: results from a large single-center case-control series

BACKGROUND

Remote magnetic navigation (RMN) has been reported as a feasible and safe mapping and ablation system for treatment of ventricular arrhythmias (VAs). However, the reported success rates have been limited with the 4- and 8-mm catheter tips.

OBJECTIVE

This study sought to report the results in a large series of consecutive patients undergoing radiofrequency (RF) catheter ablation of VAs using the RMN with the 3.5-mm magnetic open-irrigated-tip catheter (OIC).

METHODS

A total of 110 consecutive patients with a clinical history of left VA were included in the study. In all cases, an OIC was utilized for mapping and ablation. When ablation with the RMN catheters failed, a manual OIC was used to eliminate the VA. Postablation pacing maneuvers and isoproterenol were used to verify the inducibility of the VAs. Outcomes were compared with those of a group of 92 consecutive patients undergoing manual ablation by the same operator.

RESULTS

Mapping and ablation with the magnetic OIC were performed in all 110 patients with VA. Ischemic cardiomyopathy was present in 33 (30%), nonischemic in 14 (13%), and in 63 (57%) patients no structural heart disease was present. Endocardial mapping was performed in all patients, whereas both endocardial and epicardial mapping were performed in 36 (33%) patients. Compared with manual ablation, RMN was associated with a longer procedural time (2.9 +/- 1.2 hours vs. 3.3 +/- 1.1 hours, P = 0.004) and RF time (24 +/- 12 minutes vs. 33 +/- 18 minutes, P = 0.005), whereas fluoroscopic time was significantly shorter (35 +/- 22 minutes vs. 26 +/- 14 minutes, P = 0.033). During the procedures, crossover to manual ablation was required in 15 patients (14%). At 11.7 +/- 2.1 months of follow-up in the study group and 18.7 +/- 3.7 months in the manual ablation group, 85% and 86% (P = 0.817) of patients, respectively, were free of VA.

CONCLUSION

This large series of consecutive patients demonstrates that OIC ablation using RMN is effective for the treatment of left VAs.

An in vivo comparison of radiofrequency cardiac lesions formed by standard and magnetically steered 4 mm tip catheters

Background. In vivo comparison of cardiac radiofrequency ablation lesions between standard and magnetically steered 4 mm tip catheters has never been reported.Methods. High and low right atrium (RA) free wall, isthmus, right ventricle (RV) free wall and outflow tract lesions were studied macroscopically and microscopically five days after lesion formation in seven pigs. Shape, size, thrombus formation, and ablation parameters were compared. The effect of minimal, medium and high wall contact was assessed by a contact measurement utility for magnetic catheters.Results. All 14 RA free wall lesions were transmural with a similar epicardial and endocardial surface area. In the RV, the epicardial area usually appeared to be smaller than the endocardial area with standard catheters. Isthmus lesions were difficult to assess transmurality. There was no difference in endocardial area: standard 39 mm(2) (range 16 to 82 mm(2)) vs. magnetic 36 mm(2) (range 23 to 111 mm(2)). If the catheter tip was perpendicular to the tissue, magnetic lesions were more often round or oval, while standard lesions were more often elongated (p<0.05). When the catheter tip was parallel to tissue, lesions always tended to be elongated. Microscopic characteristics were similar. The contact utility was not useful. Average impedance (p<0.0001) and energy delivered (p<0.05) were less with magnetic catheters.Conclusion. Lesions from magnetically steered catheters are transmural of similar size, but with less variability than standard catheter lesions when the tip is perpendicular to the tissue. Magnetic lesions are associated with lower impedance and energy delivery. This suggests a more stable tip-to-tissue contact. (Neth Heart J 2010;18:66-71.).

Usefulness of remote magnetic navigation for ablation of ventricular arrhythmias originating from outflow regions

Monomorphic ventricular tachycardia (VT) and symptomatic monomorphic PVCs originating from the region of the right and left outflow tracts are increasingly treated by radiofrequency (RF) catheter ablation. Technical difficulties in catheter manipulation to access these outflow tract areas, very accurate mapping and reliable catheter stability are key issues for a successful treatment in this vulnerable region. VT ablation from the aortic sinus cusp (ASC) in particular carries a significant risk of perforation, of creating left coronary artery injury and of damage to the aorta and the aortic valve.This case series describes RF ablation of VT originating in the outflow region using the remote magnetic navigation system (MNS). Potential advantages of the MNS are catheter flexibility, steering accuracy and reproducibility to navigate to a desired location with a low probability of perforating the myocardium. This report supports the idea of using advanced MNS technology during RF ablation in regions which are difficult to reach and thin walled, such as parts of the outflow tract and the ASC. (Neth Heart J 2009;17:245-9.).

Remote magnetic versus manual catheter navigation for ablation of supraventricular tachycardias: a randomized, multicenter trial

INTRODUCTION

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.

METHODS AND RESULTS

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).

CONCLUSIONS

Remote magnetic catheter navigation reduces fluoroscopic time and radiofrequency lesion deliveries for the ablation of common supraventricular arrhythmias compared to manual catheter navigation.

New techniques of mapping and ablation for tachyarrhythmias in children

Advancement in mapping and ablation technologies in the past decade has made arrhythmia treatment in children safer and more effective. Electroanatomical mapping systems with features of nonfluoroscopic navigation, 3D-geometry construction and color-coded arrhythmia mapping have been extensively used to map and ablate tachycardias in children. In addition, a variety of cooled radiofrequency ablation systems have been used in selected patients to create larger and deeper lesions. Cryoenergy ablation, with its reversible nature of tissue injury during the cooling phase, is emerging as the energy of choice for ablating perinodal arrhythmias to minimize the risk of inadvertent conduction block. Other evolving ablation systems, including cryoballoon, high-intensity focused ultrasound balloon and a hybrid catheter capable of delivering both radiofrequency and cryoenergy, are also under investigation. Finally, a remote navigation system that minimizes radiation exposure and will enable physicians of all skill levels to reach difficult target sites in children is on the horizon.

Use of the Stereotaxis Niobe magnetic navigation system for percutaneous coronary intervention: results from 350 consecutive patients

INTRODUCTION

The Stereotaxis Niobe magnetic navigation system (MNS; Stereotaxis, St. Louis, MO) facilitates precise vector based navigation of magnetically-enabled guidewires for percutaneous coronary intervention (PCI) by using two permanent magnets located on opposite sides of the patient table to produce a controllable magnetic field. The objective of this study is to describe the results of a large patient series using this system, to compare the results with a historical control group, and to detail the MNS learning curve.

METHODS

We prospectively collected data on 439 lesions in 350 consecutive PCI patients using the MNS predominantly using the radial approach. All data were entered into a customized database to capture the key parameters and then compared with a previously collected stent registry from the same center.

RESULTS

In 410/439 lesions (93%) the wire crossed the lesion successfully using the MNS. Twenty-five of the 35 failures were chronic total occlusions. No wire perforations or dissections occurred in this population. Lesion crossing time was 81 +/- 168 sec (mean +/- SD), and fluoroscopy time was 64 +/- 123 sec. A clear learning curve was evident after the first 80 patients. Contrast use was reduced when compared with a historical control group. Procedural and fluoroscopy times were similar.

CONCLUSIONS

Use of the MNS may enable the successful performance of more complex procedures in the cardiac catheterization laboratory with an improvement in time efficiency.

Experience of robotic catheter ablation in humans using a novel remotely steerable catheter sheath

Background

A novel remotely controlled steerable guide catheter has been developed to enable precise manipulation and stable positioning of any eight French (Fr) or smaller electrophysiological catheter within the heart for the purposes of mapping and ablation.

Objective

To report our initial experience using this system for remotely performing catheter ablation in humans.

Methods

Consecutive patients attending for routine ablation were recruited. Various conventional diagnostic catheters were inserted through the left femoral vein in preparation for treating an accessory pathway (n = 1), atrial flutter (n = 2) and atrial fibrillation (n = 7). The steerable guide catheter was inserted into the right femoral vein through which various irrigated and non-irrigated tip ablation catheters were used. Conventional endpoints of loss of pathway conduction, bidirectional cavotricuspid isthmus block and four pulmonary vein isolation were used to determine acute procedural success.

Results

Ten patients underwent remote catheter ablation using conventional and/or 3D non-fluoroscopic mapping technologies. All procedural endpoints were achieved using the robotic control system without manual manipulation of the ablation catheter. There was no major complication. A radiation dosimeter positioned next to the operator 2.7 m away from the X-ray source showed negligible exposure despite a mean cumulative dose area product of 7,281.4 cGycm² for all ten ablation procedures.

Conclusions

Safe and clinically effective remote navigation of ablation catheters can be achieved using a novel remotely controlled steerable guide catheter in a variety of arrhythmias. The system is compatible with current mapping and ablation technologies Remote navigation substantially reduces radiation exposure to the operator.

Electronic supplementary material

The online version of this article (doi:10.1007/s10840-007-9184-z) contains supplementary material, which is available to authorized users.

Remote magnetic navigation: human experience in pulmonary vein ablation

OBJECTIVES

We aimed at assessing the feasibility and efficacy of remote magnetic navigation (MN) and ablation in patients with atrial fibrillation (AF).

BACKGROUND

This novel MN system could facilitate standardization of the procedures, reducing the importance of the operator skill.

METHODS

After becoming familiar with the system in 48 previous patients, 45 consecutive patients with AF were considered for ablation using the Niobe II remote magnetic system (Stereotaxis, St. Louis, Missouri) in a stepwise approach: circumferential pulmonary vein ablation (CPVA), pulmonary vein antrum isolation (PVAI), and, if failed, PVAI using the conventional approach. Remote navigation was done using the coordinate or the wand approach. Ablation end point was electrical disconnection of the pulmonary veins (PVs).

RESULTS

Using the coordinate approach, the target location was reached in only 60% of the sites, whereas by using the wand approach 100% of the sites could be reached. After step 2 ablation, only 1 PV in 4 patients (8%) could be electrically isolated. Charring on the ablation catheter tip was seen in 15 (33%) of the cases. In 23 patients, all PVs were isolated with the conventional thermocool catheter, and in 22 patients only the right PVs were isolated with the conventional catheter. After a mean follow-up period of 11 +/- 2 months, recurrence was seen in 5 patients (22%) with complete PVAI and in 20 patients (90%) with incomplete PVAI.

CONCLUSIONS

Remote navigation using a magnetic system is a feasible technique. With the present catheter technology, effective lesions cannot be achieved in most cases. This appears to impact the cure rate of AF patients.

[New therapy possibilities for arrhythmias using catheter ablation]

Radiofrequency current ablation has been developed over the last 20 years to be the standard approach for treating tachycardia by catheter ablation. By combining new 3-D imaging technology (CT and MRI) with 3-D electrophysiologic mapping systems, a new tool has been created to display the cardiac activation sequence of the individual. These technologies are extremely important for the treatment of complex arrhythmias such as the catheter ablation of atrial fibrillation. Instead of the conventional "point by point" linear ablation procedure, balloon catheters have been applied to a circumferential linear lesion in a "single shot" procedure using, for example, cryothermia, ultrasound or laser energy. Finally, magnetic navigation is a new steering tool for performing ablation procedures, leading to reduced exposure to ionizing radiation.