Ablation of atrial fibrillation utilizing robotic catheter navigation in comparison to manual navigation and ablation: single-center experience

Robotic applications for intracardiac and endovascular procedures

The large incisions and long recovery periods that accompany traditional cardiac surgery procedures along with the constant patient demand for minimally invasive procedures have motivated cardiac surgeons to implement the robotic technologies in their armamentarium. The robotic systems have been utilized successfully in various cardiac procedures including atrial septal defect repair, left atrial myxoma resection, MAZE procedure and left ventricular lead placement, yet coronary artery bypass and mitral valve repair still comprise the vast majority of them. This review analyzes the development of the robot-assisted cardiac surgery in recent years, its outcomes, advantages, disadvantages, its patient selection criteria as well as its economic feasibility. Robotic endovascular surgery, albeit its limited applications, is presently considered an attractive alternative to conventional endovascular approaches. The increased flexibility and precision along with the wider range of accessible anatomy provided by the endovascular robotic systems, have increased the pool of patients that can be offered minimally invasive treatment options and have helped to overcome many limitations of the traditional endovascular procedures. With this review we aimed to summarize the applications of the commercially available endovascular robotic devices, as well as the limitations and the future perspectives in the field of endovascular robotic surgery.

Robotic Assisted Versus Manual Percutaneous Coronary Intervention: Systematic Review and Meta-Analysis

INTRODUCTION

Robotics in percutaneous coronary intervention (R-PCI) has been one such area of advancement where potential benefits may include reduced operator radiation exposure, improved outcomes, and reduced rate of adverse events. Limited data exist about the benefits of R-PCI versus conventional manual PCI (M-PCI). We appraised the latest evidence in the form of a meta-analysis of observational and retrospective studies.

METHODS

A comprehensive literature search was performed in PubMed, Embase, and Cochrane to identify relevant clinical studies. Summary effects were calculated using a DerSimonian and Laird random-effects model as the pooled odds ratio or mean differences (MDs) with 95% confidence intervals (CIs). All studies adhering to the inclusion criteria of direct comparisons between R-PCI and M-PCI were evaluated.

RESULTS

Seven studies with a total of 2230 patients were identified. There was significant decrease in the chest-level operator radiation exposure (MD = -442.32; 95% CI = -675.88 to -208.76), fluoroscopy time (MD = -1.46; 95% CI = -2.92 to 0.00), and amount of contrast used (MD = -18.28; 95% CI = -24.16 to -12.41) in the robotic group compared to the manual group. PCI time and the procedural success rate was not statistically different between the 2 groups. Clinical outcomes of major adverse cardiac events, all-cause mortality, and myocardial infarction were not different between the 2 groups.

CONCLUSIONS

Robotic PCI is associated with reduced operator radiation exposure, fluoroscopy time, and amount of contrast used. While there is a significant reduction in the procedural characteristics with robotic PCI, the clinical outcomes are not different compared to M-PCI. R-PCI is safe and effective with potential benefits to both the operator and the patient simultaneously.

Contact Stability and Contact Safety of a Magnetic Resonance Imaging-Guided Robotic Catheter Under Heart Surface Motion

Contact force quality is one of the most critical factors for safe and effective lesion formation during catheter based atrial fibrillation ablation procedures. In this paper, the contact stability and contact safety of a novel magnetic resonance imaging (MRI)-actuated robotic cardiac ablation catheter subject to surface motion disturbances are studied. First, a quasi-static contact force optimization algorithm, which calculates the actuation needed to achieve a desired contact force at an instantaneous tissue surface configuration is introduced. This algorithm is then generalized using a least-squares formulation to optimize the contact stability and safety over a prediction horizon for a given estimated heart motion trajectory. Four contact force control schemes are proposed based on these algorithms. The first proposed force control scheme employs instantaneous heart position feedback. The second control scheme applies a constant actuation level using a quasi-periodic heart motion prediction. The third and the last contact force control schemes employ a generalized adaptive filter-based heart motion prediction, where the former uses the predicted instantaneous position feedback, and the latter is a receding horizon controller. The performance of the proposed control schemes is compared and evaluated in a simulation environment.

Analysis of Contact Stability and Contact Safety of a Robotic Intravascular Cardiac Catheter under Blood Flow Disturbances

This paper studies the contact stability and contact safety of a robotic intravascular cardiac catheter under blood flow disturbances while in contact with tissue surface. A probabilistic blood flow disturbance model, where the blood flow drag forces on the catheter body are approximated using a quasi-static model, is introduced. Using this blood flow disturbance model, probabilistic contact stability and contact safety metrics, employing a sample based representation of the blood flow velocity distribution, are proposed. Finally, the contact stability and contact safety of a MRI-actuated robotic catheter are analyzed using these models in a specific example scenario under left pulmonary inferior vein (LIV) blood flow disturbances.

Contact Stability Analysis of Magnetically-Actuated Robotic Catheter Under Surface Motion

Contact force quality is one of the most critical factors for safe and effective lesion formation during cardiac ablation. The contact force and contact stability plays important roles in determining the lesion size and creating a gap-free lesion. In this paper, the contact stability of a novel magnetic resonance imaging (MRI)-actuated robotic catheter under tissue surface motion is studied. The robotic catheter is modeled using a pseudo-rigid-body model, and the contact model under surface constraint is provided. Two contact force control schemes to improve the contact stability of the catheter under heart surface motions are proposed and their performance are evaluated in simulation.

Steerable catheters for minimally invasive surgery: a review and future directions

The steerable catheter refers to the catheter that is manipulated by a mechanism which may be driven by operators or by actuators. The steerable catheter for minimally invasive surgery has rapidly become a rich and diverse area of research. Many important achievements in design, application and analysis of the steerable catheter have been made in the past decade. This paper aims to provide an overview of the state of arts of steerable catheters. Steerable catheters are classified into four main groups based on the actuation principle: (1) tendon driven catheters, (2) magnetic navigation catheters, (3) soft material driven catheters (shape memory effect catheters, steerable needles, concentric tubes, conducting polymer driven catheters and hydraulic pressure driven catheters), and (4) hybrid actuation catheters. The advantages and limitations of each of them are commented and discussed in this paper. The future directions of research are summarized.

Frontiers of Medical Robotics: From Concept to Systems to Clinical Translation

Medical robotics is poised to transform all aspects of medicine—from surgical intervention to targeted therapy, rehabilitation, and hospital automation. A key area is the development of robots for minimally invasive interventions. This review provides a detailed analysis of the evolution of interventional robots and discusses how the integration of imaging, sensing, and robotics can influence the patient care pathway toward precision intervention and patient-specific treatment. It outlines how closer coupling of perception, decision, and action can lead to enhanced dexterity, greater precision, and reduced invasiveness. It provides a critical analysis of some of the key interventional robot platforms developed over the years and their relative merit and intrinsic limitations. The review also presents a future outlook for robotic interventions and emerging trends in making them easier to use, lightweight, ergonomic, and intelligent, and thus smarter, safer, and more accessible for clinical use.

Real-time optical spectroscopic monitoring of nonirrigated lesion progression within atrial and ventricular tissues

Despite considerable advances in guidance of radiofrequency ablation (RFA) therapy for the treatment of cardiac arrhythmias, success rates have been hampered by a lack of tools for precise intraoperative evaluation of lesion extent. Near-infrared spectroscopic (NIRS) techniques are sensitive to tissue structural and biomolecular properties, characteristics that are directly altered by radiofrequency (RF) treatment. In this work, a combined NIRS-RFA catheter is developed for real-time monitoring of tissue reflectance during RF energy delivery. An algorithm is proposed for processing NIR spectra to approximate nonirrigated lesion depth in both atrial and ventricular tissues. The probe optical geometry was designed to bias measurement influence toward absorption enabling enhanced sensitivity to changes in tissue composition. A set of parameters termed "lesion optical indices" are defined encapsulating spectral differences between ablated and unablated tissue. Utilizing these features, a model for real-time tissue spectra classification and lesion size estimation is presented. Experimental validation conducted within freshly excised porcine cardiac specimens showed strong concordance between algorithm estimates and post-hoc tissue assessment.

Ablation of idiopathic ventricular arrhythmia using zero-fluoroscopy approach with equivalent efficacy and less fatigue: A multicenter comparative study

The efficacy of a completely zero-fluoroscopy (ZF) approach for the catheter ablation of idiopathic ventricular arrhythmias (VAs) and whether it has advantages over the conventional fluoroscopy (F) approach are still unknown. The aim of this study was to compare the safety and efficacy of a completely ZF approach with those of the conventional F approach in the ablation of idiopathic VAs.We conducted a prospective study involving 7 centers in China. Consecutive patients (n = 489, mean age 45.3 ± 15.3 years, 44.8% male) with idiopathic VAs were recruited. Eligible participants were assigned to either a ZF (n = 163) or F (n = 326) approach at a ratio of 1:2. The completely ZF approach was successful in 163 (100%) patients for electrophysiological study, and in 151 patients (94.4%) for arrhythmia ablation with 9 cases having to switch to the F approach due to the need for coronary angiography. There was no significant difference between the ZF approach and F approach in procedural success rate (84.1% vs 85.4%, respectively), arrhythmia recurrence (1.9% vs 2.2%), or severe complications (0.6% vs 0.9%). The medical staffs using the ZF approach did not wear heavy protective apparels, thus experienced significantly less fatigue compared with those using the F approach (2.1 ± 0.7 vs 3.9 ± 1.6, P < 0.05).The completely ZF approach is as safe and efficient as the conventional F approach for the electrophysiological study and the ablation of idiopathic VAs. The medical staffs using ZF approach felt less fatigue and received less exposure to radiation.

Reduction of Fluoroscopy Time and Radiation Dosage During Catheter Ablation for Atrial Fibrillation

Radiofrequency catheter ablation has become the treatment of choice for atrial fibrillation (AF) that does not respond to antiarrhythmic drug therapy. During the procedure, fluoroscopy imaging is still considered essential to visualise catheters in real-time. However, radiation is often ignored by physicians since it is invisible and the long-term risks are underestimated. In this respect, it must be emphasised that radiation exposure has various potentially harmful effects, such as acute skin injury, malignancies and genetic disease, both to patients and physicians. For this reason, every electrophysiologist should be aware of the problem and should learn how to decrease radiation exposure by both changing the setting of the system and using complementary imaging technologies. In this review, we aim to discuss the basics of X-ray exposure and suggest practical instructions for how to reduce radiation dosage during AF ablation procedures.

Robotic surgery: disruptive innovation or unfulfilled promise? A systematic review and meta-analysis of the first 30 years

Background

Robotic surgery has been in existence for 30 years. This study aimed to evaluate the overall perioperative outcomes of robotic surgery compared with open surgery (OS) and conventional minimally invasive surgery (MIS) across various surgical procedures.

Methods

MEDLINE, EMBASE, PsycINFO, and ClinicalTrials.gov were searched from 1990 up to October 2013 with no language restriction. Relevant review articles were hand-searched for remaining studies. Randomised controlled trials (RCTs) and prospective comparative studies (PROs) on perioperative outcomes, regardless of patient age and sex, were included. Primary outcomes were blood loss, blood transfusion rate, operative time, length of hospital stay, and 30-day overall complication rate.

Results

We identified 99 relevant articles (108 studies, 14,448 patients). For robotic versus OS, 50 studies (11 RCTs, 39 PROs) demonstrated reduction in blood loss [ratio of means (RoM) 0.505, 95 % confidence interval (CI) 0.408–0.602], transfusion rate [risk ratio (RR) 0.272, 95 % CI 0.165–0.449], length of hospital stay (RoM 0.695, 0.615–0.774), and 30-day overall complication rate (RR 0.637, 0.483–0.838) in favour of robotic surgery. For robotic versus MIS, 58 studies (21 RCTs, 37 PROs) demonstrated reduced blood loss (RoM 0.853, 0.736–0.969) and transfusion rate (RR 0.621, 0.390–0.988) in favour of robotic surgery but similar length of hospital stay (RoM 0.982, 0.936–1.027) and 30-day overall complication rate (RR 0.988, 0.822–1.188). In both comparisons, robotic surgery prolonged operative time (OS: RoM 1.073, 1.022–1.124; MIS: RoM 1.135, 1.096–1.173). The benefits of robotic surgery lacked robustness on RCT-sensitivity analyses. However, many studies, including the relatively few available RCTs, suffered from high risk of bias and inadequate statistical power.

Conclusions

Our results showed that robotic surgery contributed positively to some perioperative outcomes but longer operative times remained a shortcoming. Better quality evidence is needed to guide surgical decision making regarding the precise clinical targets of this innovation in the next generation of its use.

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.

Experience matters: long-term results of pulmonary vein isolation using a robotic navigation system for the treatment of paroxysmal atrial fibrillation

BACKGROUND

Long-term results after circumferential pulmonary vein isolation (CPVI) for the treatment of paroxysmal atrial fibrillation (PAF) using a robotic navigation system (RNS) have not yet been reported.

OBJECTIVE

To evaluate long-term results of patients with PAF after CPVI using RNS.

METHODS

In this study, 200 patients (n = 151 (75.5%) male; median age 62.2 (54.7-67.7) years) with PAF were evaluated. In 100 patients, RNS (RN-group) was used for CPVI and compared to 100 manually ablated control patients (MN-group). Radiofrequency was used in conjunction with 3D electroanatomic mapping. Power was limited to 30 watts (W) at the posterior left atrial (LA) wall in the first 49 RNS patients (RN-group-a). After esophageal perforation occurred in one RN-group-a patient, maximum power was reduced to 20 W for the subsequent 51 patients (RN-group-b).

RESULTS

After a median follow-up of 2 years, single (77/100 vs 77/100, p = 0.89) and multiple (90/100 vs 93/100, p = 0.29) procedure success rates were comparable between RN-group and MN-group. Single procedure success rate was significantly lower in RN-group-a as compared to RN-group-b (65.3 vs 88.2%, p = 0.047). In RN-group-a patients, procedural times [200 (170-230) vs 152 (132-200) minutes, p < 0.01] and fluoroscopy times [16.6 (12.9-21.6) minutes vs 13.7 (9.5-19) minutes, p = 0.043] were significantly longer compared to RN-group-b patients.

CONCLUSION

Long-term success rate after CPVI using RNS was comparable to manual ablation. Despite a lower power limit of 20 W at the posterior LA wall, single procedure success rate was higher in RN-group-b as compared to RN-group-a. Procedure time and fluoroscopy time decreased, whilst success rate increased with increasing experience in the RN-group.

Efficacy of Catheter Ablation for Persistent Atrial Fibrillation

Background—

Catheter ablation (CA) is commonly performed for persistent atrial fibrillation, but few high-quality randomized controlled trials (RCTs) exist, leading to funding restrictions being proposed in several countries. We performed a random-effects meta-analysis of RCTs and non-RCTs to assess the efficacy of CA for persistent atrial fibrillation.

Methods and Results—

We systematically searched PubMed, EMBASE, CENTRAL, OpenGrey, and clinicaltrials.gov for RCTs and non-RCTs reporting clinical outcomes after CA for persistent atrial fibrillation. Forty-six eligible studies were identified containing 3819 patients. After a single procedure, CA significantly reduced the risk of recurrent atrial fibrillation compared with medical therapy (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.20–0.53; P <0.001). Outcomes were better if the pulmonary veins were encircled (OR, 0.26; 95% CI, 0.09–0.74; P =0.01), and electrical isolation reduced AF recurrence compared with purely anatomic encirclement (OR, 0.33; 95% CI, 0.13–0.86; P =0.02). Linear ablation within the left atrium (OR, 0.22; 95% CI, 0.10–0.49; P <0.001), but not complex fractionated atrial electrogram ablation (OR, 0.64; 95% CI, 0.35–1.18; P =0.15), significantly reduced AF recurrence. Results were not improved by performing more extensive linear lesion sets (OR, 0.77; 95% CI, 0.41–1.43; P =0.40) or from biatrial ablation (OR, 0.62; 95% CI, 0.31–1.24; P =0.17). Where data were available, the relative benefits seen held true both after a single or multiple procedure(s). Sensitivity analyses showed that inclusion of non-RCTs increased statistical power without biasing the calculated effect sizes.

Conclusions—

For patients with persistent atrial fibrillation, CA achieves significantly greater freedom from recurrent atrial fibrillation compared with medical therapy. The most efficacious strategy is likely to combine isolation of the pulmonary veins with limited linear ablation within the left atrium.

Comparison of robotic and manual persistent AF ablation using catheter contact force sensing: an international multicenter registry study

BACKGROUND

Catheter-based contact force sensing (CFS) technology gives detailed information regarding contact between the catheter tip and myocardium. This may result in more effective ablation procedures. The primary objective of this study was comparison of remote robotic navigation (RRN) and Manual CFS ablation. The secondary objective was to compare CFS with non-CFS ablation for both navigation modes.

METHODS

Prospective registries of consecutive cases undergoing their first ablation for persistent atrial fibrillation (AF) from six hospitals in the United Kingdom and South Africa were analyzed: 50 Manual/CFS and 50 RRN/CFS cases were included. Historical control non-CFS ablation patients were matched by propensity score, giving a total 200 patient cohort.

RESULTS

RRN/CFS was associated with improved single procedure 1-year success rates (64% vs 36%, P = 0.01) and shorter fluoroscopy times (41% reduction, P < 0.0005) than Manual/CFS ablation, without any difference in procedure times (P = 0.8). The mean contact force was higher in RRN/CFS than Manual/CFS cases (16 [15-18 g] vs 13 [12-15 g], respectively, P = 0.003). Compared with non-CFS historical controls, CFS cases had higher 1-year success rates for RRN (64% vs 36%, P = 0.01), but not Manual ablation (36% vs 38%, P = 1). Procedure times were reduced for CFS cases (20%, P < 0.005 both navigation modes), as were fluoroscopy times (Manual: 43%, RRN 83%, P < 0.005 for both). There were no differences in rates of major or minor complications for either comparison (P > 0.5).

CONCLUSIONS

A combination of RRN and CFS is associated with improved success rates at 1 year and fluoroscopy times for persistent AF ablation, compared with Manual ablation and non-CFS RRN ablation.

Endovascular ablation of atrial fibrillation

Atrial fibrillation is the most common arrhythmia. The anesthetic considerations of endovascular ablation for the treatment of atrial fibrillation are reviewed.

The comparison between robotic and manual ablations in the treatment of atrial fibrillation: a systematic review and meta-analysis

Objective

To examine in what aspects and to what extent robotic ablation is superior over manual ablation, we sought to design a meta-analysis to compare clinical outcomes between the two ablations in the treatment of atrial fibrillation.

Methods and Results

A literature search was conducted of PubMed and EMBASE databases before December 1, 2013. Data were extracted independently and in duplicate from 8 clinical articles and 792 patients. Effect estimates were expressed as weighted mean difference (WMD) or odds ratio (OR) and the accompanied 95% confidence interval (95% CI). Pooling the results of all qualified trials found significant reductions in fluoroscopic time (minutes) (WMD; 95% CI; P: -8.9; -12.54 to -5.26; <0.0005) and dose-area product (Gy×cm²) (WMD; 95% CI; P: -1065.66; -1714.36 to -416.96; 0.001) for robotic ablation relative to manual ablation, with evident heterogeneity (P<0.0005) and a low probability of publication bias. In subgroup analysis, great improvement of fluoroscopic time in patients with robotic ablation was consistently presented in both randomized and nonrandomized clinical trials, particularly in the former (WMD; 95% CI; P: -12.61; -15.13 to -10.09; <0.0005). Success rate of catheter ablation was relatively higher in patients with robotic ablation than with manual ablation (OR; 95% CI; P: 3.45; 0.24 to 49.0; 0.36), the difference yet exhibiting no statistical significance.

Conclusions

This study confirmed and extended previous observations by quantifying great reductions of fluoroscopic time and dose-area product in patients referred for robotic ablation than for manual ablation in the treatment of atrial fibrillation, especially in randomized clinical trials.

A novel four-wire-driven robotic catheter for radio-frequency ablation treatment

PURPOSE

   Robotic catheters have been proposed to increase the efficacy and safety of the radio-frequency ablation treatment. The robotized motion of current robotic catheters mimics the motion of manual ones-namely, deflection in one direction and rotation around the catheter. With the expectation that the higher dexterity may achieve further efficacy and safety of the robotically driven treatment, we prototyped a four-wire-driven robotic catheter with the ability to deflect in two- degree-of-freedom motions in addition to rotation.

METHODS

   A novel quad-directional structure with two wires was designed and developed to attain yaw and pitch motion in the robotic catheter. We performed a mechanical evaluation of the bendability and maneuverability of the robotic catheter and compared it with current manual catheters.

RESULTS

   We found that the four-wire-driven robotic catheter can achieve a pitching angle of 184.7[Formula: see text] at a pulling distance of wire for 11 mm, while the yawing angle was 170.4[Formula: see text] at 11 mm. The robotic catheter could attain the simultaneous two- degree-of-freedom motions in a simulated cardiac chamber.

CONCLUSION

   The results indicate that the four-wire-driven robotic catheter may offer physicians the opportunity to intuitively control a catheter and smoothly approach the focus position that they aim to ablate.

Current and emerging robot-assisted endovascular catheterization technologies: a review

Endovascular techniques have been embraced as a minimally-invasive treatment approach within different disciplines of interventional radiology and cardiology. The current practice of endovascular procedures, however, is limited by a number of factors including exposure to high doses of X-ray radiation, limited 3D imaging, and lack of contact force sensing from the endovascular tools and the vascular anatomy. More recently, advances in steerable catheters and development of master/slave robots have aimed to improve these practices by removing the operator from the radiation source and increasing the precision and stability of catheter motion with added degrees-of-freedom. Despite their increased application and a growing research interest in this area, many such systems have been designed without considering the natural manipulation skills and ergonomic preferences of the operators. Existing studies on tool interactions and natural manipulation skills of the operators are limited. In this manuscript, new technical developments in different aspects of robotic endovascular intervention including catheter instrumentation, intra-operative imaging and navigation techniques, as well as master/slave based robotic catheterization platforms are reviewed. We further address emerging trends and new research opportunities towards more widespread clinical acceptance of robotically assisted endovascular technologies.

Left atrial isthmus line ablation using a remote robotic navigation system: feasibility, efficacy and long-term outcome

BACKGROUND

Left atrial isthmus (LAI)-ablation in addition to circumferential pulmonary vein isolation (CPVI) may improve outcomes in select patients with atrial fibrillation (AF). However, bidirectional LAI-block is difficult to obtain. No systematic evaluation reporting on the feasibility and efficacy of LAI-ablation using a robotic navigation system (RNS) exists.

METHODS AND RESULTS

In this pilot study, CPVI combined with LAI-ablation were performed using a RNS and 3D-mapping system in 42 patients with persistent (n = 24, 57.1 %) or longstanding persistent AF. Ablation was performed using either a 3.5 mm irrigated tip catheter (ITC) with 6 (group-A, n = 16; max. 40 W, contact force 10-40 g) or (after a steam pop occurred in one patient) with a 4 mm ITC with 12 irrigation holes (group-B, n = 26; max. 30 W, contact force 10-30 g). Epicardial ablation was performed manually whenever bidirectional LAI-block could not be obtained with a maximum of 20 endocardial RF-applications. LAI-conduction block was achieved in all patients using RNS; in six patients (14.3 %), additional epicardial ablation was required to achieve LAI-block. A steam pop occurred during LAI-ablation resulting in cardiac tamponade in one patient in group-A. After a median follow-up period of 21 months, arrhythmia recurrence was seen in in 23/42 patients (18 patients with AF and 5 patients with atrial tachycardia) and repeat procedure was performed in 12 (28.6 %) patients; recovered LAI-conduction was found in 5/12 (41.7 %) patients. The RNS-group was compared to a historical group of 20 patients with manual LAI-ablation. Using RNS, LAI-block was more often achieved (42 (100 %) vs 16 (80 %), p < 0.01) and epicardial ablation was required in a significantly smaller number of patients (6 (14.3) vs 10 (50 %), p < 0.01).

CONCLUSIONS

LAI-ablation using RNS appears to be feasible in all patients. At repeat procedure, LAI-conduction can frequently occur; power and contact-force adaption appears to be mandatory to reduce the risk of complications. Using RNS, instead of a manual approach for LAI-line ablation may facilitate creation of a bidirectional LAI-block.

The Future of Pulmonary Vein Isolation - Single-shot Devices, Remote Navigation or Improving Conventional Radiofrequency Delivery by Contact Monitoring and Lesion Characterisation?

Pulmonary vein isolation is the main goal of atrial fibrillation (AF) ablation to date. Lack of isolation is associated with an increased risk of AF recurrences. Precise navigation to specific target sites, catheter stability and appropriate contact force are requisites for effective radiofrequency applications. Conventional manual-guided point-by-point radiofrequency energy delivery shows limitations to reach them, especially when performed by non-experienced electrophysiologists. New technological alternatives are rapidly arising and becoming clinically available to overcome some of the manual-guided radiofrequency delivery shortcomings. Here, we review the most recent clinical data, potential advantages, shortcomings and future directions of the new ablation strategies for pulmonary vein isolation.

Forces on cardiac implantable electronic devices during remote magnetic navigation

BACKGROUND

Remote magnetic navigation systems are used for catheter navigation in cardiac electrophysiological ablation procedures. In this setting, ferromagnetic particles will be moved by changes in the magnetic field. It is unknown to what extent cardiac implantable electronic devices (CIED) are affected by the magnetic field when using magnetic navigation, and whether these forces may exceed the limit of 5 N that is set forth by German and European norms for implanted electrodes.

METHODS

A total of 121 rhythm devices were examined in a magnetic field of 0.1 T using the NIOBE II(®) Magnetic Navigation System (Stereotaxis, St. Louis, USA). Forces acting on the devices were measured with the force measurement tool Futek LRF 400 (Futek Advanced Sensor Technology Inc., Irvine, CA, USA). A standardized protocol of different movements of the magnetic field including all three dimensions was performed and maximal forces on the CIED were assessed.

RESULTS

Out of 121 devices, 78 different pacemakers (54 different model families from 11 manufacturers) and 43 different cardioverter-defibrillators (26 different model families from 6) were examined. The mean force that could be observed was 0.33 ± 0.13 N for pacemakers (range 0.16-1.12 N) and 1.05 ± 0.11 N for cardioverter-defibrillators (range 0.86-1.38 N) when exposed to the magnetic field.

CONCLUSION

Exposure of pacemakers or implantable cardioverter-defibrillators to a magnetic field of 0.1 T does not result in a force exceeding the regulatory demanded 5 N that could damage the connected leads.

Robotic assistance and general anaesthesia improve catheter stability and increase signal attenuation during atrial fibrillation ablation

AIMS

Recurrent arrhythmias after ablation procedures are often caused by recovery of ablated tissue. Robotic catheter manipulation systems increase catheter tip stability which improves energy delivery and could produce more transmural lesions. We tested this assertion using bipolar voltage attenuation as a marker of lesion quality comparing robotic and manual circumferential pulmonary vein ablation for atrial fibrillation (AF).

METHODS AND RESULTS

Twenty patients were randomly assigned to robotic or manual AF ablation at standard radiofrequency (RF) settings for our institution (30 W 60 s manual, 25 W 30 s robotic, R30). A separate group of 10 consecutive patients underwent robotic ablation at increased RF duration, 25 W for 60 s (R60). Lesions were marked on an electroanatomic map before and after ablation to measure distance moved and change in bipolar electrogram amplitude during RF. A total of 1108 lesions were studied (761 robotic, 347 manual). A correlation was identified between voltage attenuation and catheter movement during RF (Spearman's rho -0.929, P < 0.001). The ablation catheter was more stable during robotic RF; 2.9 ± 2.3 mm (R30) and 2.6 ± 2.2 mm (R60), both significantly less than the manual group (4.3 ± 3.0 mm, P < 0.001). Despite improved stability, there was no difference in signal attenuation between the manual and R30 group. However, there was increased signal attenuation in the R60 group (52.4 ± 19.4%) compared with manual (47.7 ± 25.4%, P = 0.01). When procedures under general anaesthesia (GA) and conscious sedation were analysed separately, the improvement in signal attenuation in the R60 group was only significant in the procedures under GA.

CONCLUSIONS

Robotically assisted ablation has the capability to deliver greater bipolar voltage attenuation compared with manual ablation with appropriate selection of RF parameters. General anaesthesia confers additional benefits of catheter stability and greater signal attenuation. These findings may have a significant impact on outcomes from AF ablation procedures.

Tortuous iliac systems--a significant burden to conventional cannulation in the visceral segment: is there a role for robotic catheter technology?

PURPOSE

To attempt to quantify the effect of varying degrees of iliac tortuosity on maneuverability and "torquability" of endovascular catheters in the visceral segment, comparing conventional and robotic cannulation techniques.

MATERIALS AND METHODS

In a fenestrated endograft within a pulsatile phantom, 10 experienced operators cannulated the renal arteries via three different access vessels of varying iliac tortuosity with the use of conventional and robotic techniques. All procedures were performed in the angiography suite and recorded for blinded video assessment for quantitative (time, catheter-tip movements) and qualitative metrics (operator performance scores).

RESULTS

In total, 120 cannulations were observed. With increasing iliac tortuosity, median time and number of catheter movements required for renal cannulation with conventional techniques increased in stepwise fashion for mild, moderate, and severe iliac tortuosity (times, 7.6 min [interquartile range (IQR), 4.6-9.3 min] vs 6.9 min [4.2-11.4 min] vs 17.7 min [13.3-22.6 min], respectively; movements, 184 [IQR, 110-351] vs 251 [207-395] vs 569 [409-616], respectively). Median renal cannulation times were significantly reduced with the use of the robotic system irrespective of mild, moderate, or severe tortuosity (times, 1.4 min [IQR, 1.1-1.9 min] vs 3 min [2.3-3.3 min] vs 2.8 min [1.5-3.9 min], respectively; movements, 19 [IQR, 14-27] vs 46 [43-58] vs 45 [40-66], respectively; P < .005). Overall operator performance scores improved significantly with the use of the robotic system irrespective of iliac tortuosity severity.

CONCLUSIONS

In cases of moderate to severe iliac tortuosity, conventional catheter manipulation and control becomes an issue. The improvement in positional control and predictability seen with advanced catheter designs may be amplified in cases of severe iliac tortuosity.

Robotic catheter navigation within the left ventricle

Robotic navigation systems aim to improve ablation catheter maneuverability, tissue contact, and stability. These attributes suggest that such systems could enhance outcomes in the ablation of ventricular tachycardia (VT). To date, however, ablation has been confined to the atria. We present a case in which robotic catheter navigation alongside three-dimensional anatomical mapping enabled successful ablation of VT within the left ventricle.