The authors have no acknowledgements.

The protocol presented here is the standard approach of robotic catheter ablation RCS at the department of cardiology, Charit&#233; &#8211; Universit&#228;tsmedizin Berlin, Campus Virchow. The protocol and analysis of procedures and patient outcomes was approved by the local ethics committee of the Charit&#233; - Universit&#228;tsmedizin Berlin.
1. The Remote Catheter System (RCS)
<ol>
	<li>Attach the robotic arm to the operating table, as described before7 (Figure 1). 
	NOTE: The RCS consists of a remote catheter manipulator, which is a robotic arm that can be moved by remote control.</li>
	<li>Place the ablation catheter in the docking station of the RCS. Manipulate the catheter with the use of a remote controller, while the operating physician stays out of the radiation field7. Advance, withdraw, rotate and deflect the catheter with the use of the RCS.</li>
</ol>
2. Pre-ablation Preparation
<ol>
	<li>Position the patient on the operating table and induce deep sedation with Midazolam (0.03 mg/kg bolus) and Propofol (continuous infusion 4 mg/kg/hr).</li>
	<li>Place a temperature probe in the esophagus to measure esophageal temperature and prevent esophageal injury.</li>
	<li>Attach 12-lead ECG and surface electrodes of the 3D-Mapping system to the body of the patient.</li>
	<li>Before starting the procedure ensure that the following material are ready.
	<ol>
		<li>A transseptal needle (71 cm) and an 8.5 F SL0 sheath with guidewire. A 6 F and 7 F 25 cm sheath. A decapolar and a circular streerable diagnostic catheter. An open-irrigated ablation catheter and an ablation generator.</li>
		<li>Additionally, ensure that a contrast syringe and a pericardiocentesis tray are available for acute treatment of complications.</li>
	</ol>
	</li>
	<li>Position the robotic arm of the system in a sterile drape and ready to use. Attach the handheld remote controller to the robotic arm (Figure 1).</li>
	<li>Obtain venous access via bilateral venous puncture with a 6 F, 7 F and 8.5 F sheath and place a decapolar diagnostic catheter in the coronary sinus (CS).</li>
	<li>Perform transseptal puncture under fluoroscopic guidance using a 8.5 F long SLO sheath and a 71 cm transseptal needle.</li>
	<li>After trans-septal puncture, remove the needle and introduce a guide wire via the trans-septal sheath in the left superior pulmonary vein. Then draw back the sheath in the inferior vena cava.</li>
	<li>Place a 8.5 F long SRO sheath with a wire in the left atrium (LA), using the wire as guide to the fossa ovalis and the LA (&#8220;one-puncture, double-access&#8221;-technique). Advance an open-irrigated ablation catheter with a 3.5 mm tip with contact force measurement via the SR0 sheath to the LA.</li>
	<li>Administer Heparin with a rate of 15 UI/kg/h following a bolus of 140 IU/kg to maintain an activated clotting time (ACT) between 300 and 350 sec throughout the procedure.</li>
	<li>Once the ablation catheter has entered the LA, introduce the sheath into the LA as well. Remove the guide wire and dilator of the SLO sheath and place the ablation catheter in the left ventricle. Perform LA angiography over the sheath, while using the ablation catheter for high rate ventricular pacing to enhance contrast opacification (LA angiography is shown in Figure 2A).</li>
	<li>Advance a circular mapping catheter via the long sheath into the LA (circular mapping catheter shown in Figure 2B).</li>
	<li>Perform a 3-D anatomical reconstruction of the LA with the use of a mapping system and the circular mapping catheter. Create a 3-D-anatomical reconstruction of the LA by moving the circular catheter on the inner surface of the LA, all of the four PVs and the left atrial appendage, while using a computerized mapping system for registration of the movement in relation to a reference electrode (complete 3-D-map is shown in Figure 2C and D).</li>
	<li>Place the circular mapping catheter in the right superior PV to record PV potentials and confirm conduction block after PVI. Draw back the ablation catheter from the left ventricle to the left atrium (target position of both catheters shown in Figure 2B).</li>
	<li>Drape the RCS with a sterile cover. Position the handle of the ablation catheter in the robotic arm of the amigo system.</li>
</ol>
3. Ablation Procedure
<ol>
	<li>Perform catheter ablation as wide antral circumferential ablation (WACA) using a maximal temperature of 43 &#176;C and maximum power of 35 W (septal) or 25 W (posterior wall) respectively ad a flow rate of 17 ml/min. Manipulate the ablation catheter via the robotic arm with the use of a remote control from outside the radiation field.</li>
	<li>Perform ablation by creating point-by-point lesions around the left and right PV ostia. Measure contact force during ablation. Use the local electrogram amplitude reduction recorded on the tip of the ablation catheter, elimination or dissociation of the PV electrograms on the circular catheter and entry/exit block as ablation endpoints.</li>
	<li>Mark each ablation point on the 3-D reconstruction.</li>
	<li>Confirm conduction block for every single PV by recording potentials on the circular mapping catheter inside the PV (entry block) and by pacing from inside the PV without capture of the atrium (exit block).</li>
</ol>
4. Post-ablation Procedure and Patient Recovery
<ol>
	<li>Stop Propofol infusion and remove all catheters.</li>
	<li>Measure activated clotting time (ACT) and administer 3,000 IE protamine if ACT &#62;300 sec before removal of sheaths. Remove the sheaths and perform manual compression on the puncture site for 10 min and until the bleedings stops. Place a pressure dressing in the groin and advise the patient to lay still for 8 hr.</li>
	<li>Transfer patient to a step down unit and monitor for 4 hr and until fully responsive.</li>
	<li>Administer low molecular weight heparin as anticoagulant until discharge. Begin oral anticoagulation (Warfarin or a direct oral anticoagulant) on the day after the procedure.</li>
	<li>Perform transthoracic echocardiography on the day after the procedure as described before17. Rule out pericardial effusion and determine valvular function and left ventricular ejection fraction17.</li>
</ol>

<ol>
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J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2012+focused+update+of+the+ESC+Guidelines+for+the+management+of+atrial+fibrillation:+An+update+of+the+2010+ESC+Guidelines+for+the+management+of+atrial+fibrillation+*+Developed+with+the+special+contribution+of+the+European+Heart+Rhythm+Association.">2012 focused update of the ESC Guidelines for the management of atrial fibrillation: An update of the 2010 ESC Guidelines for the management of atrial fibrillation * Developed with the special contribution of the European Heart Rhythm Association.</a> Eur Heart J. 33 (21), 2719-2747 (2012).</li><li>Calkins, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HRS/EHRA/ECAS+expert+consensus+statement+on+catheter+and+surgical+ablation+of+atrial+fibrillation:+recommendations+for+patient+selection,+procedural+techniques,+patient+management+and+follow-up,+definitions,+endpoints,+and+research+trial+design.">HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design.</a> J Interv Card Electrophysiol. 33, 171-257 (2012).</li><li>Ouyang, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recovered+pulmonary+vein+conduction+as+a+dominant+factor+for+recurrent+atrial+tachyarrhythmias+after+complete+circular+isolation+of+the+PVs:+lessons+from+double+Lasso+technique.">Recovered pulmonary vein conduction as a dominant factor for recurrent atrial tachyarrhythmias after complete circular isolation of the PVs: lessons from double Lasso technique.</a> Circulation. 111, 127-135 (2005).</li><li>Reddy, V. 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A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Radiofrequency+ablation+vs+antiarrhythmic+drugs+as+first-line+treatment+of+paroxysmal+atrial+fibrillation+(RAAFT-2):+a+randomized+trial.">Radiofrequency ablation vs antiarrhythmic drugs as first-line treatment of paroxysmal atrial fibrillation (RAAFT-2): a randomized trial.</a> JAMA. 311 (7), 692-700 (2014).</li><li>Rillig, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Persistent+iatrogenic+atrial+septal+defect+after+a+single-puncture,+double-transseptal+approach+for+pulmonary+vein+isolation+using+a+remote+robotic+navigation+system:+results+from+a+prospective+study.">Persistent iatrogenic atrial septal defect after a single-puncture, double-transseptal approach for pulmonary vein isolation using a remote robotic navigation system: results from a prospective study.</a> Europace. 12 (3), 331-336 (2010).</li><li>Hliv&#225;k, P., Ml&#269;ochov&#225;, H., Peichl, P., Cih&#225;k, R., Wichterle, D., Kautzner, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Robotic+navigation+in+catheter+ablation+for+paroxysmal+atrial+fibrillation:+midterm+efficacy+and+predictors+of+postablation+arrhythmia+recurrences.">Robotic navigation in catheter ablation for paroxysmal atrial fibrillation: midterm efficacy and predictors of postablation arrhythmia recurrences.</a> J Cardiovasc Electrophysiol. 22 (5), 534-540 (2011).</li><li>Saliba, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atrial+fibrillation+ablation+using+a+robotic+catheter+remote+control+system:+initial+human+experience+and+long-term+follow-up+results.">Atrial fibrillation ablation using a robotic catheter remote control system: initial human experience and long-term follow-up results.</a> J Am Coll Cardiol. 51 (25), 2407-2411 (2008).</li><li>Haldar, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contact+force+sensing+technology+identifies+sites+of+inadequate+contact+and+reduces+acute+pulmonary+vein+reconnection:+a+prospective+case+control+study.">Contact force sensing technology identifies sites of inadequate contact and reduces acute pulmonary vein reconnection: a prospective case control study.</a> Int J Cardiol. 168 (2), 1160-1166 (2013).</li><li>Tilz, R. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unexpected+high+incidence+of+esophageal+injury+following+pulmonary+vein+isolation+using+robotic+navigation.">Unexpected high incidence of esophageal injury following pulmonary vein isolation using robotic navigation.</a> J Cardiovasc Electrophysiol. 21 (8), 853-858 (2010).</li><li>Hahn, R. 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Free access to this article was sponsored by Catheter Robotics, Inc. Alexander Wutzler has received moderate lecture fees from Biotronik and travel grants from Boston Scientific. Leif-Hendrik Boldt has received moderate lecture fees from Catheter Robotics, St. Jude Medical and Boston Scientific.

It has been reported by the group of Haissaguerre that antral PVI is a curative treatment for paroxysmal AF1,2,10. More recent data compared PVI with medical treatment in paroxysmal AF and found a lower rate of AF recurrence after PVI compared to antiarrhythmia treatment after 2 years of follow up11. However, as the authors of the RAAFT-2 trial conclude, recurrence rates after both types of treatment are high11. Therefore, improvement of the technique is necessary.
It has been discussed before, that manual catheter control may result in inaccurate catheter movements5,7. It therefore is of clinical interest, if ablation with the use of a robotic arm is feasible and effective. On the other hand, increased stability could lead to severe complications such as cardiac wall perforation and injury of adjacent structures. In a previously published study, is was shown that left atrial mapping and PVI with the RCS is feasible and effective. No major complication was observed7, confirming previously published results on the safety of robotic ablation12,13. Operator fluoroscopy exposure is significantly lower without decrease of procedural success rates7.
The first critical step is the trans-septal puncture. There is a significant risk of atrial wall perforation and cardiac tamponade as well as injury to the aorta. Puncture should be performed in the fossa ovalis under fluoroscopic guidance and with a CS catheter as landmark to minimize the risk. The next critical step is the 3-D-reconstruction. Accuracy of the 3-D-image depends on patient anatomy, catheter stability and patient immobilisation. Therefore, sufficient patient sedation is crucial to avoid movement artefacts and create a reliable image. The third critical step is the application of the ablation lesions. Optima catheter stability and wall contact should be achieved.
One of the major advantages of the RCS (compared to other robotic systems) is that it is possible to switch to manual ablation during the procedure and back to robotic ablation. This can be very helpful in case of anatomical abnormalities or difficult structures (e.g., a common ostium of left PVs). The operator may perform ablation manually in difficult areas and use the RCS for the remaining ablation sites. Therefore, switching from robotic to manual ablation could be a solution for difficult situations during the procedure.
As mentioned before, measurement of contact force could add valuable information for the operator7. In the case presented here, contact force and catheter tissue contact with the use of the mapping system are assessed. Contact force mapping could further increase efficacy and safety of the procedure14.
It is important to note, that despite the use of RCS certain steps of the procedure still have to be carried out manually, such as trans-septal puncture and positioning of the circular mapping catheter inside the pulmonary veins. Yet, those steps generally can be carried out quickly and do not necessitate long fluoroscopy time.
Furthermore, tactile feedback is lacking during robotic catheter ablation. The physician has to rely on fluoroscopy, 3-D reconstruction and contact force measurement. Studies on the use of contact force measurement during AF ablation have shown that tactile feedback is of very limited value for the estimation of contact force15. Therefore, contact force measurement is considered superior to tactile feedback in terms of efficacy. However, the value of tactile feedback for safety endpoints (e.g., the prevention of atrial wall perforation) is less clear, since incidence of perforation is much lower than incidence of AF recurrence due to PV reconnection. Theoretically, measurement of contact force should also prevent excessively high force and wall perforation. One previous study found a relatively high incidence of esophageal lesions after robotic AF ablation16. Even though a different robotic system was used and no contact force was measured the results of the study by Tilz et al. may at least in part apply to the RCS used in our protocol. Large randomized prospective trials are missing, but numerous studies on initial experience with the RCS support the view that robotic ablation with the RCS is safe7-9.
We here present a protocol for robotic ablation of AF. In contrast to previous studies we use a catheter with contact force measurement to increase safety and efficacy of the procedure. Operator fluoroscopy exposure can significantly be reduced. Catheter stability is most likely increased and outcomes are comparable to manual ablation. Additionally, switching between manual of robotic ablation is easy, which is a unique aspect of the RCS. In conclusion, ablation with the use of the RCS may in the future optimize PVI procedures, reduce operator radiation exposure and increase accuracy of the technique. Therefore, robotic ablation with the RCS is a promising approach in the treatment of AF.

AF is the most common cardiac arrhythmia with a prevalence of 1 - 2% in the general population. Symptoms include palpitations, dizziness, dyspnea and reduced exercise capacity. Furthermore, stroke risk is substantially increased in AF patients. Over the past decade, PVI has become an established curative treatment option for patients suffering from AF1,2.
The basic principle of PVI is the application of circular lesions around the PV ostium with radiofrequency (RF) energy to create an electrical conduction block between PV and the left atrium. This conduction block prevents atrial fibrillation, which is triggered by irregular electric activity originating from the PV. However, transmural lesions are required to achieve conduction block and application of transmural lesions can be challenging. Re-conduction and recurrence of atrial fibrillation after catheter ablation occur in 20 - 40% of the cases1,2.
As it has been shown recently, sufficient catheter-tissue contact and catheter stability are prerequisites of effective ablation lesions3,4. Numerous techniques and ablation approaches have been developed to improve catheter-stability, streerability and catheter-tissue contact. Among others, robotic systems are of special interest. The advantages and principles of robotic ablation have been discussed before5-7. These systems may not only improve catheter stability by minimizing artefacts of manual catheter manipulation, but also have the advantage of reduced fluoroscopy exposure for the operator since the system is operated via remote control from outside the radiation field. A novel robotic system with remote catheter steerability has recently been introduced. Feasibility and efficacy of this system for PVI and other electrophysiological procedures, such as AV-nodal-reentry-tachcardia, accessory pathways or atrial flutter and atrial or ventricular tachycardias has been evaluated7-9. A significant reduction of operator fluoroscopy exposure compared to manual ablation was shown, while all other procedural parameters and success rate at 12-month follow up were not significantly different 7.
A procedure of left atrial mapping and PVI with the use of this new remote catheter system is presented here.
After obtaining vascular access via the femoral vein, interatrial trans-septal puncture is performed using a long trans-septal sheath and a trans-septal needle under fluoroscopic guidance. After trans-septal puncture, the needle is removed and a guide wire is place via the trans-septal sheath in the left superior pulmonary vein. Then the sheath in drawn back into the inferior vena cava and an ablation catheter is positioned in the LA, using the wire as guide to the fossa ovalis and the LA (&#8220;one-puncture, double-access&#8221;-technique). Once the ablation catheter has entered the LA, the sheath is moved forward to the LA as well, the guide wire is removed and the ablation catheter is positioned in the left ventricle. A left atrial angiography is performed over the sheath, while the ablation catheter is used for high rate ventricular pacing to enhance contrast opacification. After LA angiography is completed, a circular mapping catheter is positioned via the long sheath into the LA and a 3-D-anatomical reconstruction if the LA is performed with the use of a mapping system. The circular mapping catheter is positioned in the right superior PV to record PV potentials and confirm conduction block after PVI. The ablation catheter is drawn back from the left ventricle into the left atrium and the handle of the ablation catheter is positioned in the robotic arm of the amigo system. During the ablation procedure, the operator manipulates the ablation catheter via the robotic arm with the use of a remote control. The ablation is performed by creating point-by-point lesions around the left and right PV ostia. Conduction block is confirmed by recording the PV potentials on the circular mapping catheter and by pacing maneuvers.
CASE PRESENTATION
Perform this procedure in a patient with symptomatic drug-refractory paroxysmal AF with no severe co-morbidities and no prior cardiac surgery. Perform the pre-diagnostic tests that are described below.
DIAGNOSIS, ASSESSMENT, AND PLAN
Diagnosis of AF is confirmed by repeated holter ECG recordings, including correlation of AF and symptoms (palpitations, dyspnea, reduced exercise capacity). If AF is recorded and symptoms are reported despite treatment with at least 1 antiarrhythmic drug, PVI is indicated for the treatment of symptomatic drug-refractory AF according to actual guidelines. PVI is scheduled and written informed consent is obtained from the patient. Prior to PVI physical examination, laboratory testing, transesophageal and transthoracic echocardiography are performed to rule out left atrial thrombus and severe structural heart disease. PVI procedure is performed in a fasting state under deep sedation. Vitamin K antagonists are discontinued 5 days prior to the ablation, low molecular weight heparin is started when international normalized ratio is &#60;2.

<table><tbody><tr><td>Amigo Remote Catheter System</td><td>Catheter Robotics/Boston Scientific</td><td></td><td>Robotic system</td></tr><tr><td>BRK transseptal needle (71 cm)</td><td>St Jude Medical</td><td></td><td>Needle for transseptal puncture</td></tr><tr><td>8.5 F SR0 sheath</td><td>Swartz/St Jude Medical</td><td></td><td>long sheath to access the left atrium and to provide stability for the ablation catheter</td></tr><tr><td>8.5 F SL0 sheath</td><td>Swartz/St Jude Medical</td><td></td><td>long sheath to access the left atrium and to provide stability for the LASSO catheter</td></tr><tr><td>LASSO catheter + cable</td><td>Biosense Webster</td><td></td><td>Circular mapping catheter (7 F) to measure electrical activity in the pulmonary veins</td></tr><tr><td>IBI inquiry decapolar catheter + cable</td><td>St Jude Medical</td><td></td><td>Coronary sinus catheter</td></tr><tr><td>Thermocool SmartTouch</td><td>Biosense Webster</td><td></td><td>open-irrigated ablation catheter (7,5 F) with a 3,5 mm tip and contact force measurement, the tip is heated to apply thermal lesions in the left atril myocardium</td></tr><tr><td>Heparin</td><td>Braun</td><td></td><td>1. heparinized irrgation solution for preparation of the sheath,2. intravenous unfractionated heparin for procedural anticoagulation</td></tr><tr><td>Propofol</td><td>Fresenius</td><td></td><td>Procedural sedation</td></tr><tr><td>Midazolam</td><td>Roche</td><td></td><td>Procedural sedation</td></tr><tr><td>NaCl solution</td><td>Braun</td><td></td><td>Irrigation solution for the ablation catheter</td></tr><tr><td>CARTO</td><td>Biosense Webster</td><td></td><td>Mapping System and contact force measurement; this system allows a 3-D- reconstrcution of the left atrium and navigation of the moving catheter</td></tr><tr><td>UHS-20</td><td>Biotronik</td><td></td><td>Electrical Stimulator for stimulation of cardiac tissue via catehetr tip of the LASSO-, CS- or ablation catheter</td></tr><tr><td>EP Shuttle</td><td>Stockert</td><td></td><td>Ablation Generator for application of energy and thermal lesion via the catheter tip</td></tr><tr><td>6 F sheath</td><td>Terumo</td><td></td><td>sheath to provide femoral access</td></tr><tr><td>Lifepack 15 defibrillator</td><td>Physio Control</td><td></td><td>Defibrillator/monitoring device</td></tr><tr><td>Pericardiocentesis set</td><td>variuous</td><td></td><td>Emergency set</td></tr></tbody></table>

robotic ablation of atrial fibrillation

Background: Pulmonary vein isolation (PVI) is an established treatment for atrial fibrillation (AF). During PVI an electrical conduction block between pulmonary vein (PV) and left atrium (LA) is created. This conduction block prevents AF, which is triggered by irregular electric activity originating from the PV. However, transmural atrial lesions are required which can be challenging. Re-conduction and AF recurrence occur in 20 - 40% of the cases. Robotic catheter systems aim to improve catheter steerability. Here, a procedure with a new remote catheter system (RCS), is presented. Objective of this article is to show feasibility of robotic AF ablation with a novel system. Materials and Methods: After interatrial trans-septal puncture is performed using a long sheath and needle under fluoroscopic guidance. The needle is removed and a guide wire is placed in the left superior PV. Then an ablation catheter is positioned in the LA, using the sheath and wire as guide to the LA. LA angiography is performed over the sheath. A circular mapping catheter is positioned via the long sheath into the LA and a three-dimensional (3-D) anatomical reconstruction of the LA is performed. The handle of the ablation catheter is positioned in the robotic arm of the Amigo system and the ablation procedure begins. During the ablation procedure, the operator manipulates the ablation catheter via the robotic arm with the use of a remote control. The ablation is performed by creating point-by-point lesions around the left and right PV ostia. Contact force is measured at the catheter tip to provide feedback of catheter-tissue contact. Conduction block is confirmed by recording the PV potentials on the circular mapping catheter and by pacing maneuvers. The operator stays out of the radiationfield during ablation. Conclusion: The novel catheter system allows ablation with high stability on low operator fluoroscopy exposure.

Endpoint of the procedure is complete electrical isolation of all PVs. It was shown recently in a study with 119 patients, that procedural parameters and outcomes were not significantly different in procedures with the RCS (n = 40) compared to the standard manual approach (n = 79). Statistical analysis (Mann-Whitney-U-test) revealed no significant differences in procedure duration (159.1 &#177; 45.4 vs. 146 &#177; 30.1 min, p = 0.19) total energy delivery (78146.3 &#177; 26992.4 vs. 87963.9 &#177; 79202.1 Ws, p = 0.57) and total fluoroscopy time (21.2 &#177; 8.6 vs. 23.9 &#177; 5.4 min, p = 0.15). Yet, operator fluoroscopy exposure was significantly reduced in the RCS group (13.4 &#177; 6.1 vs. 23.9 &#177; 5.4 min, p &#60; 0.001) 7.
Additionally, analysis of the first 21 patients of PVI with the RCS was performed. Patient characteristics and clinical data are depicted in Table 1. This analysis represents a single-centre experience. Data was analysed for a series of 20 patients with PVI (data from one patient was unavailable due to technical reasons). Statistical analysis of procedural parameters was performed using the Mann-Whitney-U-test. Results are presented as mean &#177; standard deviation (SD) for continuous variables and as numbers and percentages for discrete variables. Total procedure duration was 137.3 &#177; 24.2 min, total fluoroscopy time was 26.1 &#177; 6.1 min, operator fluoroscopy exposure was 14.8 &#177; 6.1 min. Isolation of pulmonary veins (PVs) was achieved in all patients with the use of the remote system. Comparison of procedure duration, total fluoroscopy time and operator fluoroscopy exposure duration between was performed to analyse procedural improvement with growing experience with the technique. Mean duration of cases 11 - 20 was significantly reduced compared to cases 1 - 10 (125.5 &#177; 18.1 vs. 149 &#177; 24.6 min, p = 0.029), while reduction of total fluoroscopy time (23.1 &#177; 6.4 vs. 28.7 &#177; 9.3 min, p = 0.21) and operator fluoroscopy exposure time (12.9 &#177; 5.35 vs. 17 &#177; 6.48 min, p = 0.2) did not reach significance (Figures 3 and 4). Measurement of contact force was not performed. No complications occurred.
These initial results suggest that left atrial mapping and PVI is feasible and effective. Isolation of the PVs was achieved in all cases. The learning curve was short with a significant reduction of procedure time in case11-20. Operator fluoroscopy exposure was considerably reduced.
<img alt="Figure 1" src="/files/ftp_upload/52560/52560fig1.jpg" /> 
Figure 1. Remote catheter system. Robotic arm attached to the catheter table before (A and B) and after (C) insertion of the ablation catheter.Handheld remote controller (D and E). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52560/52560fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/52560/52560fig2.jpg" /> 
Figure 2. Images of the left atrium. Left atrial angiography in left anterior oblique view with the use of a SLO sheath for angiography and an ablation catheter for high rate ventricular pacing (A). Circular mapping catheter positioned in the right superior pulmonary vein (B). 3-D-reconstruction of the left atrium. The circular mapping catheter is shown in the right superior pulmonary vein. Left atrium is shown in anterior-posterior (C) and right lateral (D) view. Abl = ablation catheter, CS = coronary sinus catheter, LAA = left atrial appendage, LA = left atrium, LIPV = left inferior pulmonary vein, LSPV = left superior pulmonary vein, RIPV = right inferior pulmonary vein, RSPV = right superior pulmonary vein. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52560/52560fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/52560/52560fig3.jpg" width="500" /> 
Figure 3. Procedural data for procedure 1 - 10 vs. 11 - 20. Procedure duration (A), total fluoroscopy time (B), and operator fluoroscopy exposure time (C) for procedure 1 - 10 and 11 - 20. * statistically significant.
<img alt="Figure 4" src="/files/ftp_upload/52560/52560fig4.jpg" /> 
Figure 4. Procedure duration and total fluoroscopy time for procedure 1 - 20. 
<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td colspan="2">Baseline Characteristics</td>
		</tr>
		<tr>
			<td>Number of patients</td>
			<td>21</td>
		</tr>
		<tr>
			<td>Age (years) (SD)</td>
			<td>64.1 (8.5)</td>
		</tr>
		<tr>
			<td>Male (%)</td>
			<td>17 (81)</td>
		</tr>
		<tr>
			<td>BMI (SD)</td>
			<td>28.1 (4.1)</td>
		</tr>
		<tr>
			<td>Paroxysmal AF (%)</td>
			<td>14 (66.7)</td>
		</tr>
		<tr>
			<td>Hypertension (%)</td>
			<td>16 (76.2)</td>
		</tr>
		<tr>
			<td>CAD (%)</td>
			<td>5 (23.8)</td>
		</tr>
		<tr>
			<td>LVEF (%) (SD)</td>
			<td>56.9 (4.6)</td>
		</tr>
		<tr>
			<td>LA diameter (mm) (SD)</td>
			<td>42.4 (4.9)</td>
		</tr>
	</tbody>
</table>
Table 1. Patients&#39; characteristics and clinical data. Characteristics and clinical data of the first 20 patients undergoing AF ablation with the remote catheter system at our center. AF = atrial fibrillation, CAD = coronary artery disease, LA = left atrium, LVEF = left ventricular ejection fraction

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Robotic Ablation of Atrial Fibrillation

Pulmonary vein isolation (PVI) with an ablation catheter is a curative treatment for atrial fibrillation (AF). Robotic catheter systems aim to improve catheter steerability. Here, a procedure with a new robotic catheter system is presented. The goal of the procedure is electrical block between pulmonary vein and left atrium.

Background: Pulmonary vein isolation (PVI) is an established treatment for atrial fibrillation (AF). During PVI an electrical conduction block between ...

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19.6K Views.  Charité — Universitätsmedizin Berlin, Campus Virchow. Pulmonary vein isolation (PVI) with an ablation catheter is a curative treatment for atrial fibrillation (AF). Robotic catheter systems aim to improve catheter steerability. Here, a procedure with a new robotic catheter system is presented. The goal of the procedure is electrical block between pulmonary vein and left atrium.

Video: Robotic Ablation of Atrial Fibrillation

Remote Magnetic Navigation for Accurate, Real-time Catheter Positioning and Ablation in Cardiac Electrophysiology Procedures

New remote navigation systems have been developed to improve current limitations of conventional manually guided catheter ablation in complex cardiac substrates such as left atrial flutter. This protocol describes all the clinical and invasive interventional steps performed during a human electrophysiological study and ablation to assess the accuracy, safety and real-time navigation of the Catheter Guidance, Control and Imaging (CGCI) system. Patients who underwent ablation of a right or left atrium flutter substrate were included. Specifically, data from three left atrial flutter and two counterclockwise right atrial flutter procedures are shown in this report. One representative left atrial flutter procedure is shown in the movie. This system is based on eight coil-core electromagnets, which generate a dynamic magnetic field focused on the heart. Remote navigation by rapid changes (msec) in the magnetic field magnitude and a very flexible magnetized catheter allow real-time closed-loop integration and accurate, stable positioning and ablation of the arrhythmogenic substrate.

This report provides a detailed description of a new remote navigation system based on magnetic driven forces, which has been recently introduced as a new robotic tool for human cardiac electrophysiology procedures.

New remote navigation systems have been developed to improve current limitations of conventional manually guided catheter ablation in complex cardiac ...

Catheter Ablation in Combination With Left Atrial Appendage Closure for Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting millions of individuals worldwide 1-3. The rapid, irregular, and disordered electrical activity in the atria gives rise to palpitations, fatigue, dyspnea, chest pain and dizziness with or without syncope 4, 5. Patients with AF have a five-fold higher risk of stroke 6.
Oral anticoagulation (OAC) with warfarin is commonly used for stroke prevention in patients with AF and has been shown to reduce the risk of stroke by 64% 7. Warfarin therapy has several major disadvantages, however, including bleeding, non-tolerance, interactions with other medications and foods, non-compliance and a narrow therapeutic range 8-11. These issues, together with poor appreciation of the risk-benefit ratio, unawareness of guidelines, or absence of an OAC monitoring outpatient clinic may explain why only 30-60% of patients with AF are prescribed this drug 8.
The problems associated with warfarin, combined with the limited efficacy and/or serious side effects associated with other medications used for AF 12,13, highlight the need for effective non-pharmacological approaches to treatment. One such approach is catheter ablation (CA), a procedure in which a radiofrequency electrical current is applied to regions of the heart to create small ablation lesions that electrically isolate potential AF triggers 4. CA is a well-established treatment for AF symptoms 14, 15, that may also decrease the risk of stroke. Recent data showed a significant decrease in the relative risk of stroke and transient ischemic attack events among patients who underwent ablation compared with those undergoing antiarrhythmic drug therapy 16.
Since the left atrial appendage (LAA) is the source of thrombi in more than 90% of patients with non-valvular atrial fibrillation 17, another approach to stroke prevention is to physically block clots from exiting the LAA. One method for occluding the LAA is via percutaneous placement of the WATCHMAN LAA closure device. The WATCHMAN device resembles a small parachute. It consists of a nitinol frame covered by fabric polyethyl terephthalate that prevents emboli, but not blood, from exiting during the healing process. Fixation anchors around the perimeter secure the device in the LAA (Figure 1). To date, the WATCHMAN is the only implanted percutaneous device for which a randomized clinical trial has been reported. In this study, implantation of the WATCHMAN was found to be at least as effective as warfarin in preventing stroke (all-causes) and death (all-causes) 18. This device received the Conformit&eacute; Europ&eacute;enne (CE) mark for use in the European Union for warfarin eligible patients and in those who have a contraindication to anticoagulation therapy 19.
Given the proven effectiveness of CA to alleviate AF symptoms and the promising data with regard to reduction of thromboembolic events with both CA and WATCHMAN implantation, combining the two procedures is hoped to further reduce the incidence of stroke in high-risk patients while simultaneously relieving symptoms. The combined procedure may eventually enable patients to undergo implantation of the WATCHMAN device without subsequent warfarin treatment, since the CA procedure itself reduces thromboembolic events. This would present an avenue of treatment previously unavailable to patients ineligible for warfarin treatment because of recurrent bleeding 20 or other warfarin-associated problems.
The combined procedure is performed under general anesthesia with biplane fluoroscopy and TEE guidance. Catheter ablation is followed by implantation of the WATCHMAN LAA closure device. Data from a non-randomized trial with 10 patients demonstrates that this procedure can be safely performed in patients with a CHADS2 score of greater than 1 21. Further studies to examine the effectiveness of the combined procedure in reducing symptoms from AF and associated stroke are therefore warranted.

Catheter ablation is combined with placement of the WATCHMAN Left Atrial Appendage Closure Device to prevent ischemic stroke in a patient with non-valvular atrial fibrillation.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting millions of individuals worldwide 1-3. The rapid, irregular, and ...

Direct Pressure Monitoring Accurately Predicts Pulmonary Vein Occlusion During Cryoballoon Ablation

Cryoballoon ablation (CBA) is an established therapy for atrial fibrillation (AF). Pulmonary vein (PV) occlusion is essential for achieving antral contact and PV isolation and is typically assessed by contrast injection. We present a novel method of direct pressure monitoring for assessment of PV occlusion.
Transcatheter pressure is monitored during balloon advancement to the PV antrum. Pressure is recorded via a single pressure transducer connected to the inner lumen of the cryoballoon. Pressure curve characteristics are used to assess occlusion in conjunction with fluoroscopic or intracardiac echocardiography (ICE) guidance. PV occlusion is confirmed when loss of typical left atrial (LA) pressure waveform is observed with recordings of PA pressure characteristics (no A wave and rapid V wave upstroke). Complete pulmonary vein occlusion as assessed with this technique has been confirmed with concurrent contrast utilization during the initial testing of the technique and has been shown to be highly accurate and readily reproducible.
We evaluated the efficacy of this novel technique in 35 patients. A total of 128 veins were assessed for occlusion with the cryoballoon utilizing the pressure monitoring technique; occlusive pressure was demonstrated in 113 veins with resultant successful pulmonary vein isolation in 111 veins (98.2%). Occlusion was confirmed with subsequent contrast injection during the initial ten procedures, after which contrast utilization was rapidly reduced or eliminated given the highly accurate identification of occlusive pressure waveform with limited initial training.
Verification of PV occlusive pressure during CBA is a novel approach to assessing effective PV occlusion and it accurately predicts electrical isolation. Utilization of this method results in significant decrease in fluoroscopy time and volume of contrast.

Effective pulmonary vein isolation utilizing a cryoballoon depends on complete pulmonary vein occlusion. The point of occlusion can be effectively predicted by direct analysis of pulmonary vein pressure waveform analysis during balloon inflation using a simple and reproducible technique.

Cryoballoon  ablation (CBA) is an established therapy for atrial fibrillation (AF).  Pulmonary vein (PV) occlusion is essential for achieving antral ...

Non-fluoroscopic Catheter Tracking for Fluoroscopy Reduction in Interventional Electrophysiology

A technological platform (MediGuide) has been recently introduced for non-fluoroscopic catheter tracking. In several studies, we have demonstrated that the application of this non-fluoroscopic catheter visualization system (NFCV) reduces fluoroscopy time and dose by 90-95% in a variety of electrophysiology (EP) procedures. This can be of relevance not only to the patients, but also to the nurses and physicians working in the EP lab. Furthermore, in a subset of indications such as supraventricular tachycardias, NFCV enables a fully non-fluoroscopic procedure and allows the lab staff to work without wearing lead aprons. With this protocol, we demonstrate that even complex procedures such as ablations of atrial fibrillation, that are typically associated with fluoroscopy times of &#62;30 min in conventional settings, can safely be performed with a reduction of &#62;90% in fluoroscopy exposure by the additional use of NFCV.

Radiation exposure is an underestimated risk in complex ablation procedures. Here, we describe a protocol to significantly decrease fluoroscopy time and dosage for both the patient and the lab staff by using a novel non-fluoroscopic catheter visualization system.

A technological platform (MediGuide) has been recently introduced for non-fluoroscopic catheter tracking. In several studies, we have demonstrated that ...

Reduction of Iatrogenic Atrial Septal Defects with an Anterior and Inferior Transseptal Puncture Site when Operating the Cryoballoon Ablation Catheter

The cryoballoon catheter ablates atrial fibrillation (AF) triggers in the left atrium (LA) and pulmonary veins (PVs) via transseptal access. The typical transseptal puncture site is the fossa ovalis (FO) &#8211; the atrial septum&#8217;s thinnest section. A potentially beneficial transseptal site, for the cryoballoon, is near the inferior limbus (IL). This study examines an alternative transseptal site near the IL, which may decrease the frequency of acute iatrogenic atrial septal defect (IASD). Also, the study evaluates the acute pulmonary vein isolation (PVI) success rate utilizing the IL location. 200 patients were evaluated by retrospective chart review for acute PVI success rate with an IL transseptal site. An additional 128 IL transseptal patients were compared to 45 FO transseptal patients by performing Doppler intracardiac echocardiography (ICE) post-ablation to assess transseptal flow after removal of the transseptal sheath. After sheath removal and by Doppler ICE imaging, 42 of 128 (33%) IL transseptal patients demonstrated acute transseptal flow, while 45 of 45 (100%) FO transseptal puncture patients had acute transseptal flow. The difference in acute transseptal flow detection between FO and IL sites was statistically significant (P &#60;0.0001). Furthermore, 186 of 200 patients (with an IL transseptal puncture) did not need additional ablation(s) and had achieved an acute PVI by a &#8220;cryoballoon only&#8221; technique. An IL transseptal puncture site for cryoballoon AF ablations is an effective location to mediate PVI at all four PVs. Additionally, an IL transseptal location can lower the incidence of acute transseptal flow by Doppler ICE when compared to the FO. Potentially, the IL transseptal site may reduce later IASD complications post-cryoballoon procedures.

The goal of this study is to demonstrate the preferential location of transseptal puncture during a cryoballoon catheter ablation procedure for the treatment of atrial fibrillation.

The cryoballoon catheter ablates atrial fibrillation (AF) triggers in the left atrium (LA) and pulmonary veins (PVs) via transseptal access. The typical ...

Ablation of Ischemic Ventricular Tachycardia Using a Multipolar Catheter and 3-dimensional Mapping System for High-density Electro-anatomical Reconstruction

Ventricular tachycardia (VT) in patients with ischemic cardiomyopathy mainly results from endocardial scars after myocardial infarction; those scars represent zones of slow conduction that allow the occurrence and maintenance of reentrant circuits. Catheter ablation enables substrate modification of those low voltage areas and thus can help to alter the scar tissue in such a way that arrhythmias cannot appear anymore. Hospitalizations of concerned patients decrease, quality of life and outcome rise. Consequently, VT ablation represents a growing field in electrophysiology, especially for patients with endocardial scars in ischemic heart disease after myocardial infarction. However, ablation of ventricular tachycardia remains one of the most challenging procedures in the electrophysiology lab. Precise scar definition and localization of abnormal potentials are critical for ablation success. The following manuscript describes the use of a multipolar mapping catheter and 3-dimensional (3D) mapping system to create a high density electro-anatomical map of the left ventricle including a precise scar representation as well as mapping of fractionated and late potentials in order to allow a highly accurate substrate modification.

With the following protocol, we provide an approach to Ventricular Tachycardia (VT) ablation using high density mapping with a multipolar catheter and 3D mapping system enhancing the success of the procedure.

Ventricular tachycardia (VT) in patients with ischemic cardiomyopathy mainly results from endocardial scars after myocardial infarction; those scars ...

Cooling or Warming the Esophagus to Reduce Esophageal Injury During Left Atrial Ablation in the Treatment of Atrial Fibrillation

Ablation of the left atrium using either radiofrequency (RF) or cryothermal energy is an effective treatment for atrial fibrillation (AF) and is the most frequent type of cardiac ablation procedure performed. Although generally safe, collateral injury to surrounding structures, particularly the esophagus, remains a concern. Cooling or warming the esophagus to counteract the heat from RF ablation, or the cold from cryoablation, is a method that is used to reduce thermal esophageal injury, and there are increasing data to support this approach. This protocol describes the use of a commercially available esophageal temperature management device to cool or warm the esophagus to reduce esophageal injury during left atrial ablation. The temperature management device is powered by standard water-blanket heat exchangers, and is shaped like a standard orogastric tube placed for gastric suctioning and decompression. Water circulates through the device in a closed-loop circuit, transferring heat across the silicone walls of the device, through the esophageal wall. Placement of the device is analogous to the placement of a typical orogastric tube, and temperature is adjusted via the external heat-exchanger console.

The goal of this protocol is to describe the use of esophageal temperature modulation to counteract esophageal thermal injury from left atrial ablation for the treatment of atrial fibrillation.

Ablation of the left atrium using either radiofrequency (RF) or cryothermal energy is an effective treatment for atrial fibrillation (AF) and is the most ...

Reduced Procedure Time and Variability with Active Esophageal Cooling During Radiofrequency Ablation for Atrial Fibrillation

Various methods are utilized during radiofrequency (RF) pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF) to protect the esophagus from inadvertent thermal injury. Active esophageal cooling is increasingly being used over traditional luminal esophageal temperature (LET) monitoring, and each approach may influence procedure times and the variability around those times. The objective of this study is to measure the effects on procedure time and variability in procedure time of two different esophageal protection strategies utilizing advanced informatics techniques to facilitate data extraction. Trained clinical informaticists first performed a contextual inquiry in the catheterization laboratory to determine laboratory workflows and observe the documentation of procedural data within the electronic health record (EHR). These EHR data structures were then identified in the electronic health record reporting database, facilitating data extraction from the EHR. A manual chart review using a REDCap database created for the study was then performed to identify additional data elements, including the type of esophageal protection used. Procedure duration was then compared using summary statistics and standard measures of dispersion.&#160;A total of 164 patients underwent radiofrequency PVI over the study timeframe; 63 patients (38%) were treated with LET monitoring, and 101 patients (62%) were treated with active esophageal cooling. The mean procedure time was 176 min (SD of 52 min) in the LET monitoring group compared to 156 min (SD of 40 min) in the esophageal cooling group (P = 0.012). Thus, active esophageal cooling during PVI is associated with reduced procedure time and reduced variation in procedure time when compared to traditional LET monitoring.

This study utilized advanced informatics techniques to compare procedure duration in patients undergoing radiofrequency atrial ablation treated with active esophageal cooling to those treated with traditional luminal esophageal temperature monitoring. Contextual inquiry, workflow analysis, and data mapping were utilized. The findings demonstrated reduced procedure time and variability with active cooling.

Various methods are utilized during radiofrequency (RF) pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF) to protect the ...

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

It is now well recognized that heart failure (HF) patients with left bundle branch block (LBBB) derive substantial clinical benefits from cardiac resynchronization therapy (CRT), and LBBB has become one of the important predictors for CRT response. The conventional tachypacing-induced HF model has several major limitations, including absence of stable LBBB and rapid reversal of left ventricular (LV) dysfunction after cessation of pacing. Hence, it is essential to establish an optimal model of chronic HF with isolated LBBB for studying CRT benefits. In the present study, a canine model of asynchronous HF induced by left bundle branch (LBB) ablation and 4 weeks of rapid right ventricular (RV) pacing is established. The RV and right atrial (RA) pacing electrodes via the jugular vein approach, together with an epicardial LV pacing electrode, were implanted for CRT performance. Presented here are the detailed protocols of radiofrequency (RF) catheter ablation, pacing leads implantation, and rapid pacing strategy. Intracardiac and surface electrograms during operation were also provided for a better understanding of LBB ablation. Two-dimensional speckle tracking imaging and aortic velocity time integral (aVTI) were acquired to validate the chronic stable HF model with LV asynchrony and CRT benefits. By coordinating ventricular activation and contraction, CRT uniformed the LV mechanical work and restored LV pump function, which was followed by reversal of LV dilation. Moreover, the histopathological study revealed a significant restoration of cardiomyocyte diameter and collagen volume fraction (CVF) after CRT performance, indicating a histologic and cellular reverse remodeling elicited by CRT. In this report, we described a feasible and valid method to develop a chronic asynchronous HF model, which was suitable for studying structural and biologic reverse remodeling following CRT.

The establishment of a chronic asynchronous heart failure (HF) model by rapid pacing combined with left bundle branch ablation is presented. Two-dimensional speckle tracking imaging and aortic velocity time integral are applied to validate this stable HF model with left ventricular asynchrony and the benefits of cardiac resynchronization therapy.

It is now well recognized that heart failure (HF) patients with left bundle branch block (LBBB) derive substantial clinical benefits from cardiac ...

Biology

Assessing Continuity Index in Pulmonary Vein Isolation with Esophageal Cooling 

Determination of Continuity Index Values in Atrial Fibrillation Ablation with Proactive Esophageal Cooling

Radiofrequency (RF) ablation to perform pulmonary vein isolation (PVI) for the treatment of atrial fibrillation involves some risk to collateral structures, including the esophagus. Proactive esophageal cooling using a dedicated device has been granted marketing authorization by the Food and Drug Administration (FDA) to reduce the risk of ablation-related esophageal injury due to RF cardiac ablation procedures, and more recent data also suggest that esophageal cooling may contribute to improved long-term efficacy of treatment. A mechanistic underpinning explaining these findings exists through the quantification of lesion placement contiguity defined as the Continuity Index (CI). Kautzner et al. quantified the CI by the order of lesion placement, such that whenever a lesion is placed non-adjacent to the prior lesion, the CI is incremented by the number of segments the catheter tip has moved over. 
To facilitate real-time calculation of the CI and encourage further adoption of this instrument, we propose a modification in which the placement of non-adjacent lesions increments the CI by only one unit, avoiding the need to count potentially nebulous markers of atrial segmentation. The objective of this protocol is to describe the methods of calculating the CI both prospectively during real-time PVI cases and retrospectively using recorded case data. A comparison of the results obtained between cases that utilized proactive esophageal cooling and cases that used luminal esophageal temperature (LET) monitoring is then provided.

Author Spotlight: Improving Lesion Contiguity in Pulmonary Vein Isolation via Proactive Esophageal Cooling

This protocol describes the methods used to determine the continuity index in patients undergoing pulmonary vein isolation procedures using radiofrequency ablation and demonstrates the differences in continuity index between ablation procedures using proactive esophageal cooling as compared to procedures using traditional luminal esophageal temperature monitoring.

Robotic Ablation of Atrial Fibrillation

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