Introduction Mapping and catheter ablation of cardiac arrhythmias can be technically complex and challenging. Currently the majority of such procedures are performed using manually deflectable catheters. These catheters have limited range and flexibility and rely on operator skill to manoeuvre the catheter tip and maintain stability at target sites within the heart. 1 Fig. 1 left right  The physician’s workstation 2 Fig. 2 top left bottom left right  Remote catheter manipulator The RCM is a robot designed to accept the Artisan catheter. The RCM receives catheter position commands from the control computers as issued by the IMC. Acting on these commands, the RCM uses servo motors to control its motions. These motions transfer to the Artisan catheter’s pull wires, ultimately determining the position of the catheter tip. Steerable guide catheter (Artisan) 3 x y Fig. 3 SIG SOG  We report our initial experience in testing the hypothesis that robotic remote catheter ablation in humans is feasible and safe using existing catheters and mapping systems. This study was approved by St. Mary’s Hospital local ethics committee. Materials and methods 1 only and Table 1 Inclusion and exclusion criteria Inclusion criteria Exclusion criteria Suitable for catheter mapping/ablation Severe cerebrovascular disease 18–85 years of age Serum creatinine > 2.5 Body Mass Index < 40 Active gastrointestinal bleeding Signed informed consent Active infection or fever  Short life expectancy <1 year  Significant anemia  Severe electrolyte imbalance  Allergy to contrast  Congestive heart failure (NYHA Class IV), ejection fraction <30%  Unstable angina requiring emergent percutaneous intervention  Recent myocardial infarction within 2 weeks  Bleeding or clotting disorders  Uncontrolled diabetes  Inability to receive IV anticoagulants Various diagnostic catheters were inserted and manipulated manually through the left femoral vein for initial arrhythmia mapping. These included Josephson™ quadripolar catheters in combination with Cardima™, Halo™ and Lasso™ catheters for mapping a left lateral accessory pathway, two atrial flutter circuits and for seven atrial fibrillation ablation procedures respectively. Transeptal access was performed to treat the patients with an accessory pathway and atrial fibrillation. In the cases of atrial fibrillation ablation, a single transeptal puncture was made from the left femoral vein, the needle was removed, the sheath withdrawn into the right atrium and an .035 J-wire left across the puncture site. The Artisan containing the ablation catheter was then guided from the right femoral vein through the puncture site into the left atrium for ablation. It is useful to note that although the outer guide is able to cross the inter-atrial septum, for the majority of cases, this remains on the right atrial side of the septum and catheter navigation within the left atrium was done mainly using the inner sheath. The pulmonary veins were mapped manually with a Lasso™ placed via the left femoral transeptal sheath. For left-sided procedures titrated intravenous heparin boluses of up to 10,000 units were given every 30 min to maintain an activated clotting time of at least 300 s. The Artisan control catheter was inserted into the right femoral vein through a short non-irrigated 14 Fr sheath. Various conventional 4 and 8 mm non-irrigated tip (EPT Blazer II™) and irrigated-tip (Navistar™ Thermocool™) catheters were deployed through the lumen of the Artisan for ablation. Continuous heparinised saline flushing was maintained through the side ports of the inner and outer sheaths of the Artisan. Conventional mapping was complemented with 3D non-fluoroscopic mapping technologies as required, including NavX™ (St. Jude Medical, St. Paul, MN, USA), CARTO™ and CARTOMERGE™ (Biosense Webster Inc., Diamond Bar, CA, USA). All 3D maps, computed tomography scan registration, mapping and ablation were performed remotely. In the atrial fibrillation cases some ablation points were ‘drag’ lesions used to construct ablation lines. Conventional endpoints of loss of accessory pathway function, bidirectional cavotricuspid isthmus block and four pulmonary vein isolation were used to determine immediate procedural success. At the end of the procedure the Artisan was removed from the 14 Fr venous sheath manually. If heparin had been given during the procedure, intravenous protamine was administered and removal of the 14 Fr sheath was done under manual pressure once the activated clotting time was less than 150 s. Results Twenty patients were studied. In ten, only mapping to specific anatomical sites was performed using the Hansen system for regulatory purposes without any procedural complication related to using the system. The other ten patients underwent remote catheter ablation and are the subjects of this report. All mapping and ablation endpoints were achieved using only the Sensei robotic control system, without manual manipulation of the ablation catheter in these ten patients. 2 4 5 Fig. 4 left right SGC Abl  Fig. 5 top left top right bottom left bottom right red  Table 2 Robotic ablation procedural data Patient Sex Age Diagnosis Procedure Mapping system Catheter tip Number of RFs RF time Total procedure time Flouro time Patient DAP Workstation DAP 1 F 76 Atrial flutter CTI conventional 4 mm irrigated 38 103 140 44.5 8,383 0 2 M 55 Permanent atrial fibrillation PVI, left atrial maze NavX™ 4 mm irrigated 63 191 259 116 24,667 0 3 M 50 Paroxysmal atrial fibrillation PVI NavX™ 4 mm irrigated 42 111 170 52 11,216 0 4 M 41 Accessory pathway Pathway ablation conventional 4 mm non-irrigated 3 31 106 13.4 779 0 5 F 71 Atrial flutter CTI conventional 8 mm non-irrigated 15 33 70 19.9 1,042 0 6 M 53 Persistent atrial fibrillation PVI roof line, MI NavX™ 4 mm irrigated 39 123 165 55.2 6,577 0 7 M 73 Persistent atrial fibrillation PVI and roof line NavX™ 4 mm irrigated 46 143 166 64.2 4,739 0 8 F 63 Paroxysmal atrial fibrillation PVI and roof line NavX™ 4 mm irrigated 48 118 157 42.8 7,271 0 9 F 46 Atrial ectopy/paroxysmal atrial fibrillation PVI CARTOMERGE™ 4 mm irrigated 31 143 124 41.7 2,262 0 10 M 54 Persistent atrial fibrillation PVI and roof line CARTO™ 4 mm irrigated 68 155 223 43.4 5,878 0 CTI PVI MI RF 2 No major complication occurred. One patient (accessory pathway) had a small <1 cm pericardial effusion measured on echocardiogram 24 h post-procedure. The patient was not on post-procedural anticoagulation and was discharged without any clinical sequalae. There were no femoral haematomas associated with the use of the system. 2 Discussion Complex ablation procedures to treat cardiac arrhythmias can be time consuming and technically challenging. There is always a need to improve procedural success, reduce procedure times and minimize fluoroscopy screening times. These issues are largely governed by the skill and efficiency of the operator using manually controlled catheters that may be limited in their flexibility and manoeuvrability. Computer assisted remote catheter ablation systems may minimize some of these difficulties by reducing the manual skill required, potentially reducing the operator’s learning curves. 1 5 Electromechanical systems are an alternative means of remote catheter ablation. An in-depth comparison of the advantages and disadvantages of both systems is beyond the remit of this paper; particularly as robotic catheter navigation has only just been developed whereas magnetic navigation has already established itself in clinical trials. However, one can see the advantages of being able to use a remote navigation system that is portable; does not exclude patients that have metal implants or devices and is compatible with other mapping systems and catheters. It remains to be seen whether robotic navigation can achieve the long-term efficacy and safety of magnetic navigation. In particular, whilst catheter-tip stability is improved, the amount of energy applied and the duration needed to achieve successful ablation without increasing the risk of “pops” and resultant perforation needs to be determined. 6 Safety in vivo 7 9 6 Fig. 6 close-up edited view white yellow  In the authors’ personal experience using this system, although visual representation of the forces applied at the catheter tip is better than none at all, it does not replace the tactile responses that experienced operators use to prevent damage or perforation of cardiac structures. The Intellisense system allows the operator to predetermine what pressure level is deemed to be ‘excessive’ and if pressures exceed this arbitrary threshold the tip of the virtual catheter and the pressure waveform changes colour as a warning but there is no auditory alarm, requiring the operator to be constantly vigilant. Another potential problem is the potential for thrombus to form within the Artisan’s sheaths. This was avoided by high flow continuous flushing and appropriate heparinisation. No thrombotic complication occurred in this study. Fluoroscopy and radiation exposure 10 11 Versatility This study has demonstrated the system’s compatibility with various irrigated and non-irrigated tipped ablation catheters as well as its use with existing non-fluoroscopic mapping systems such as CARTO™ and NavX™. There was no technical difficulty in setting up and performing mapping and ablation in any of the cases. In the case using a Thermocool Navistar 8 mm tip catheter, insertion into the Artisan was not problematic, though the fit prevented the Intellisense force feedback system from moving the catheter tip. Mapping and ablation was performed unhindered but with the Intellisense system switched off. Limitations n 3 n Table 3 Conventional ablation procedural data Ablation procedure Number RFs RF time Total procedure time Flouro time DAP Atrial fibrillation – 111 ± 51 (44–171) 143 ± 52 (45–204) 61.4 ± 31 (24–121) 6,636 ± 5,867 (1,776–19,489) Atrial flutter 7 ± 5 (2–18) 21 ± 16 (4–56) 62 ± 24 (25–94) 23 ± 13.3 (7–49) 1,369 ± 1,108 (189–3,596) Accessory pathway 3 ± 3 (1–11) 14 ± 25 (1–83) 97 ± 53 (36–186) 22.9 ± 12.2 (9–44) 2,899 ± 3,224 (219–11,055) n 2 The operators themselves underwent an intensive two day training course to familiarise themselves with the set-up and use of the equipment in animals prior to the study being undertaken. During the animal case the physician is instructed in how to drive to certain places in the right atrium, how to cross the septum and drive to defined points in the left atrium and also how to create a 3D atrial geometry. It is understandable that great caution was employed with its use in the first human subjects. Despite this, the data are sufficient to conclude that the system can work safely and effectively in humans and can achieve conventional endpoints of ablation. Conclusions The Sensei robotic control system in combination with the Artisan control catheter is compatible with current mapping and ablation technologies, enabling clinically effective remote navigation of ablation catheters. Remotely controlled catheter ablation for cardiac arrhythmias using this system reduces operator radiation exposure. Electronic supplementary material Below is the link to the electronic supplementary material.
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