We acknowledge the funding by SJM.

All patients signed an informed consent form after all typical complications of an ablation procedure such as pericardial effusion, vascular complications at the access site, stroke/TIA, and esophago-atrial fistula, were explained. This fulfilled the requirements of the local ethics committee. No patient subgroup had to be excluded (e.g., patients with pacemakers or ICD); only general contraindications for AF ablation procedures (e.g., contraindication for anticoagulation, hyperthyreosis, valvular AF, etc.) had to be addressed.
1. Patient Setup
<ol>
	<li>On the day of hospital admission, perform a routine physical exam including resting ECG, blood analysis, transesophageal echo and a contrast-enhanced CT scan of the heart on the patient. International normalized ratio (INR) should be between 2 and 3.</li>
	<li>If novel anticoagulants are used, skip either 1 dose (rivaroxaban) or 2 doses (dabigatran and apixaban) before the procedure.</li>
</ol>
2. Ablation Procedure
<ol>
	<li>Place the 3D EAMS patches on the patient per manufacturer&#8217;s instructions on the thorax (front and back; left and right), neck, and belly. Monitor oxygen saturation using a finger clip, as well as the non-invasive blood pressure. Perform disinfection of the groin region.</li>
	<li>Administer midazolam (2-3 mg, i.v.) and fentanyl (0.025 mg, i.v.) as premedication to slightly sedate the patient and to provide some analgesics during the puncture of the femoral vessels.</li>
	<li>Start the procedure with the injection of 40 ml of 1% Mepivacain to the left and right groin areas.</li>
	<li>Perform punctures of the femoral vessels. Start the puncture for venous access 1 cm medial to the femoral artery, 1 cm below the connection between symphysis and crista iliaca anterior superior. Perform the arterial puncture 1 cm superior to the venous access sites.
	<ol>
		<li>Perform two 7F punctures in the left femoral vein for placing two diagnostic catheters: 1 steerable decapolar catheter for the coronary sinus (CS) and 1 steerable decapolar catheter for the right ventricular apex. After a successful puncture of the vessels, advance a guidewire, remove the puncture needle and place the sheath over the wire per the Seldinger technique.</li>
		<li>Next, perform 2 punctures on the right side: a 4F puncture in the right femoral artery for invasive blood pressure measurements, and an 11F one in the right femoral vein for the transseptal sheath. Before inserting the 11F sheath, control the intravasal position of the wire using fluoroscopy and then place the sheath.</li>
	</ol>
	</li>
	<li>Administer heparin (100 IU/kg, i.v.) for anticoagulation.</li>
	<li>Check the activated clotting time (ACT) every 20 min; the target for the anticoagulation is an ACT between 250 and 350 sec. If necessary, administer boluses of heparin according to ACT measurements.</li>
	<li>During the procedure, maintain the patient in a deep analgosedation using midazolam (2-5 mg), fentanyl (0.05-0.1 mg) and propofol (bolus 0.5 mg/kg and constant basal rate of 0.5 mg/kg/h).</li>
	<li>Acquire 2 live fluoroscopy or cine loops using the X-Ray fluoroscopy system in a right anterior oblique projection (RAO 15&#176;) and a left anterior oblique projection (LAO 50&#176;), each approximately 3 sec long (Figure 3 and Video 1)7,14,15. 
	NOTE: The NFCV projects the catheter tips on these pre-recorded cine loops allowing a non-fluoroscopic placement of the diagnostic catheters.</li>
	<li>Place one of the diagnostic catheters in the CS by first advancing the catheter tip to the superior vena cava (SVC), then pulling it back slowly and deflecting it to bring it close to the bundle of His.
	<ol>
		<li>Deflect the catheter to its maximum allowable curve and perform a clockwise rotation to bring the tip to the CS ostium. Advance the catheter as deep as possible in the CS to achieve a stable position. Then, place a landmark on the catheter tip using the NFCV system to mark the location.</li>
		<li>Use the other diagnostic catheter to place landmarks for superior vena cava (SVC), inferior vena cava (IVC) and fossa ovalis (see Figure 1).</li>
	</ol>
	</li>
	<li>Perform a trans-atrial septal puncture using a long steerable sheath8.
	<ol>
		<li>Insert a long guidewire to the SVC and verify the position with fluoroscopy. Advance the steerable sheath over the wire to the junction between the SVC and the right atrium (RA). Insert a long needle into the dilator, pull back the sheath until it &#8220;jumps&#8221; into the fossa ovalis.</li>
		<li>Perform the puncture by advancing the needle and injecting contrast dye (15 ml of Ultravist 300) to verify the correct position of the sheath in the left atrium (LA).</li>
		<li>Once the needle tip is in the LA, advance the dilator to LA, disconnect it from the sheath and advance the sheath over the dilator into the LA. Deflect the sheath and slowly remove the needle and dilator from the sheath.</li>
		<li>Aspire 10 ml of blood from the sheath and carefully flush the sheath with heparinized saline. Flush the sheath with heparinized saline constantly at a flow rate of 2 ml/hr. 
		NOTE: The diagnostic catheter is used for electroanatomical reconstruction of the LA and pulmonary venous anatomy. Coronary sinus catheter remains in place and serves as the reference catheter for the 3D mapping system.</li>
	</ol>
	</li>
	<li>Insert the long sheath in the superior pulmonary veins and perform 2 new fluoroscopy or cine loops in RAO 15&#176; (right PV) and LAO 50&#176; (left PV) during injection of 15 ml of contrast dye (Ultravist 300)7,14,15.</li>
	<li>Perform fusion of the electroanatomical map with 3D reconstructed CT anatomy. Map anatomical landmarks in the LA carefully and use for this co-registration process.
	<ol>
		<li>For example, use the junction of the left inferior pulmonary vein (LIPV) to the LA body. Take at least 10 - 15 points for the fusion process and then double-check and optimize the co-registration process with the roving catheter. Upon completion, the segmented CT model is positioned at an anatomically correct position in 3D space.</li>
	</ol>
	</li>
	<li>Place a temperature probe with 3 thermocouples trans-orally to measure the intra-luminal intra-esophageal temperature at the level of the LA.</li>
	<li>Insert the ablation catheter via the transseptal sheath.</li>
	<li>Perform ablation around the ipsilateral pulmonary veins by using power settings of 35 W (anterior) and 25 W (posterior) at an irrigation rate of 17 ml/min.</li>
	<li>If the intra-luminal temperature exceeds 39 &#176;C, immediately stop the ablation and adjust the power settings, lowering the minimum power to be 20 W. In case of temperature rise despite reduction of energy settings, consider modifying the lesion setting to go more antral if it is too close to the esophagus.
	<ol>
		<li>If the temperature still exceeds 41 &#176;C, perform an esophagoscopy the day after the ablation to exclude mucosal thermal damage which could develop to an esophago-atrial fistula10.</li>
	</ol>
	</li>
	<li>Check the completeness of the pulmonary vein isolation using a decapolar circular catheter by pacing maneuvers at maximum power (usually 10 mA/msec) from all bipoles of the spiral catheter. Make sure that the stimulus does not capture the LA by checking signals on the CS catheter. Verify that there is no LA capture in any of the pulmonary veins.
	<ol>
		<li>If necessary, detect and close &#8220;gaps&#8221; in the lesion set: move the ablation catheter around the circumferential lesions and stimulate with maximum output from the tip of the ablation catheter. If the atrium is captured, start ablation until the local capture disappears16. Use this &#8220;pace-and-ablate&#8221;-technique around all pulmonary veins.</li>
	</ol>
	</li>
	<li>Once the isolation line around the pulmonary veins is completed, perform a voltage map of the left atrium to determine a healthy atrium (shown in purple) or a fibrotic atrium (shown in blue, yellow, and grey) [see Figure 1 and 2]17. Use the cut-off values 0.5 mV for normal tissue and 0.2 mV for scar tissue17.
	<ol>
		<li>Use the ablation catheter or the diagnostic catheter and start in the pulmonary vein antrum. Make sure that there is sufficient contact with the catheter tip and register the local signal amplitude to the 3D mapping system. For a normal sized LA, take points covering the entire LA body and PV antrum (100-150 points).</li>
	</ol>
	</li>
	<li>Perform a test for inducibility with 20 sec burst-pacing from the coronary sinus with cycle lengths of 300 msec, 250 msec and 200 msec or to atrial refractory time. If a stable atrial tachycardia or atrial flutter is induced, map and ablate accordingly.</li>
	<li>If atrial fibrillation is induced, perform an electrical cardioversion (with 200 J biphasic shock) and terminate the procedure.</li>
	<li>Remove the transseptal sheath and catheters.</li>
	<li>Antagonize heparin by injecting protaminsulfat (10,000 IU, i.v.) and remove the sheaths from the groin.</li>
</ol>
3. Post-procedural Management
<ol>
	<li>Perform 10 min of manual femoral compression. After removal of the sheaths manually, compress the puncture sites on both sides. Check if there is still active bleeding after 5 min. If not, continue compression for at least an additional 5 min and place the pressure bandage for 6 hr.</li>
	<li>Subject the patient to 6 hr of bed rest before the patient is remobilized.</li>
	<li>After removal of the pressure bandage and checking the femoral vessels clinically (palpation and auscultation), deliver the next dose of anticoagulant drugs (warfarin or novel anticoagulants).</li>
</ol>

<ol>
	<li>Caponi, D., 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=Ablation+of+atrial+fibrillation:+Does+the+addition+of+three-dimensional+magnetic+resonance+imaging+of+the+left+atrium+to+electroanatomic+mapping+improve+the+clinical+outcome?),+A+randomized+comparison+of+carto-merge+vs.+Carto-xp+three-dimensional+mapping+ablation+in+patients+with+paroxysmal+and+persistent+atrial+fibrillation.">Ablation of atrial fibrillation: Does the addition of three-dimensional magnetic resonance imaging of the left atrium to electroanatomic mapping improve the clinical outcome?), A randomized comparison of carto-merge vs. Carto-xp three-dimensional mapping ablation in patients with paroxysmal and persistent atrial fibrillation.</a> Europace. 12, 1098-1104 (2010).</li><li>Flugelman, M. Y., 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=Medical+positioning+system:+A+technical+report.">Medical positioning system: A technical report.</a> EuroIntervention. 4, 158-160 (2008).</li><li>Jeron, 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=First-in-man+(fim)+experience+with+the+magnetic+medical+positioning+system+(mps)+for+intracoronary+navigation.">First-in-man (fim) experience with the magnetic medical positioning system (mps) for intracoronary navigation.</a> EuroIntervention. 5, 552-557 (2009).</li><li>Sommer, P., Rolf, S., Richter, S., Hindricks, G., Piorkowski, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=non-fluoroscopic+catheter+tracking:+The+mediguide+system.">non-fluoroscopic catheter tracking: The mediguide system.</a> Herzschrittmacherther Elektrophysiol. 23, 289-295 (2012).</li><li>Sommer, P., 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=Initial+experience+in+ablation+of+typical+atrial+flutter+using+a+novel+three-dimensional+catheter+tracking+system.">Initial experience in ablation of typical atrial flutter using a novel three-dimensional catheter tracking system.</a> Europace. 15, 578-581 (2013).</li><li>Sommer, P., 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=Mediguide+in+supraventricular+tachycardia:+Initial+experience+from+a+multicentre+registry.">Mediguide in supraventricular tachycardia: Initial experience from a multicentre registry.</a> Europace. 15, 1292-1297 (2013).</li><li>Rolf, 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=Catheter+ablation+of+atrial+fibrillation+supported+by+novel+nonfluoroscopic+4d+navigation+technology.">Catheter ablation of atrial fibrillation supported by novel nonfluoroscopic 4d navigation technology.</a> Heart Rhythm. 10, 1293-1300 (2013).</li><li>Piorkowski, C., 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=Steerable+versus+nonsteerable+sheath+technology+in+atrial+fibrillation+ablation:+A+prospective,+randomized+study.">Steerable versus nonsteerable sheath technology in atrial fibrillation ablation: A prospective, randomized study.</a> Circ Arrhythm Electrophysiol. 4, 157-165 (2011).</li><li>Eitel, C., 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=Circumferential+pulmonary+vein+isolation+and+linear+left+atrial+ablation+as+a+single-catheter+technique+to+achieve+bidirectional+conduction+block:+The+pace-and-ablate+approach.">Circumferential pulmonary vein isolation and linear left atrial ablation as a single-catheter technique to achieve bidirectional conduction block: The pace-and-ablate approach.</a> Heart Rhythm. 7, 157-164 (2010).</li><li>Halm, U., 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=Thermal+esophageal+lesions+after+radiofrequency+catheter+ablation+of+left+atrial+arrhythmias.">Thermal esophageal lesions after radiofrequency catheter ablation of left atrial arrhythmias.</a> Am J Gastroenterol. 105, 551-556 (2010).</li><li>Vallakati, 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=Impact+of+nonfluoroscopic+mediguide+tracking+system+on+radiation+exposure+in+radiofrequency+ablation+procedures+(less-rads+registry)-an+initial+experience.">Impact of nonfluoroscopic mediguide tracking system on radiation exposure in radiofrequency ablation procedures (less-rads registry)-an initial experience.</a> J Interv Card Electrophysiol. 38, 95-100 (2013).</li><li>Roguin, A., Goldstein, J., Bar, O., Goldstein, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brain+and+neck+tumors+among+physicians+performing+interventional+procedures.">Brain and neck tumors among physicians performing interventional procedures.</a> Am J Cardiol. 111 (9), 1368-1372 (2013).</li><li>Richter, 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=Cardiac+resynchronization+therapy+device+implantation+using+a+new+sensor-based+navigation+system:+results+from+the+first+human+use+study.">Cardiac resynchronization therapy device implantation using a new sensor-based navigation system: results from the first human use study.</a> Circ Arrhythm Electrophysiol. 6 (5), 917-923 (2013).</li><li>Sommer, P., 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=Non-fluoroscopic+catheter+visualization+in+AF+ablation:+experience+from+375+consecutive+procedures.">Non-fluoroscopic catheter visualization in AF ablation: experience from 375 consecutive procedures.</a> Circ Arrhythm Electrophysiol. 7 (5), 869-874 (2014).</li><li>Sommer, P., Richter, S., Hindricks, G., Rolf, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-fluoroscopic+catheter+visualization+using+MediGuide+technology:+experience+from+the+first+600+procedures.">Non-fluoroscopic catheter visualization using MediGuide technology: experience from the first 600 procedures.</a> J Interv Card Electrophysiol. 40 (3), 209-214 (2014).</li><li>Eitel, C., 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=Circumferential+pulmonary+vein+isolation+and+linear+left+atrial+ablation+as+a+single-catheter+technique+to+achieve+bidirectional+conduction+block:+the+pace-and-ablate+approach.">Circumferential pulmonary vein isolation and linear left atrial ablation as a single-catheter technique to achieve bidirectional conduction block: the pace-and-ablate approach.</a> Heart Rhythm. 7 (2), 157-164 (2010).</li><li>Rolf, 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=Tailored+Atrial+Substrate+Modification+Based+On+Low-Voltage+Areas+in+Catheter+Ablation+of+Atrial+Fibrillation.">Tailored Atrial Substrate Modification Based On Low-Voltage Areas in Catheter Ablation of Atrial Fibrillation.</a> Circ Arrythm Electrophysiol. 7, 483-489 (2014).</li></ol>

SR, SeR and MD received modest lecture fees by St. Jude Medical, Inc. PS and GH received modest lecture fees and are consultants for SJM.

Radiation exposure for interventional cardiologists and electrophysiologists is an underestimated risk because of its unpredictable side-effects. Current literature reveals a higher incidence of left-sided brain-tumors among this subgroup of clinicians, suggesting that the proximity of the left hemisphere to the X-Ray source may be a culprit12. The latency between radiation exposure and diagnosis of neoplasia has been reported to be 20 years or more. Therefore, today&#8217;s interventionalists should use all technological options to reduce radiation exposure to a minimum.
The NFCV system can help reduce fluoroscopy exposure without affecting procedure time14,15 with a workflow that was adapted several times over the past 3 years in order to minimize radiation exposure according to the ALARA principle.
3D mapping systems can help to improve the understanding of complex 3-dimensional structures, but the basic orientation for the operator is generated using conventional fluoroscopy.
The transseptal puncture remains the largest contributing step (75-80%) of the radiation dose during these procedures since no sensor-equipped material for use with NFCV technology is currently available. Especially in unexperienced hands this represents the most critical step in that procedure- other imaging modalities (such as intracardiac or transesophageal echo) can contribute to safe punctures and low complication rates.
The NFCV is not only used in ablation procedures but also in complex implantations such as cardiac resynchronization therapy (CRT). In these procedures, the system allows the reduction of fluoroscopy burden by 75-80% compared to conventional implantations13. A recent publication could show that after a learning curve of 30 - 40 procedures a median fluoroscopy time of 1.1 min for 50 consecutive patients is feasible and safe14. This was confirmed when extending the data acquisition to &#62;500 patients (see Figure 4).
<img alt="Figure 4" src="/files/ftp_upload/52606/52606fig4highres.jpg" width="600" /> 
Figure 4: <a href="https://www.jove.com/files/ftp_upload/52606/52606fig4highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The limitation of the current available system is that only the tips of the catheters are visualized. Unexperienced operators will probably not be able to interpolate from the orientation of the tip to know what the position of the catheter shaft will be. Furthermore, the system is not able to visualize the transseptal sheath yet. Only a limited choice of catheters are currently available- therefore only a limited number of different procedures is suitable using NFCV technology.
In near future more devices and tools will be available that are equipped with a sensor to be visualized non-fluoroscopically. The system here basically works as a cardiovascular platform for different procedures;&#160;electrophysiology is just the first application that has been introduced.

Catheter ablation has become a standard therapy in the treatment of many arrhythmias. While different ablation strategies have been proposed and are currently applied, all ablation procedures share one commonality in their necessity for the use of fluoroscopy to visualize catheters. Heavy reliance on the use of live x-ray for ablation procedures was alleviated in the 1990s with the advent of 3D electroanatomical mapping systems (EAMS) that helped to significantly reduce radiation time and dosage. Integration of cardiac imaging using magnetic resonance imaging (MRI) and computed tomography (CT) was shown to even further reduce fluoroscopy exposure during ablation procedures1. More recently, a new technology for catheter visualization, called the MediGuide-(MG) technology, has been introduced that can further facilitate reduction in radiation exposure2,3. Details have been previously described4,5. Briefly, single-coil sensors embedded in the catheter tip can be accurately localized by an electromagnetic field. Information about the 3D position and orientation of the tools is then transferred to the fluoroscopy system and is used to visualize the catheter tip in a virtual bi-planar view projected on 2 pre-recorded cine loops. It has been previously shown that the application of the MG technology can lead to a significant reduction in fluoroscopy burden by using diagnostic catheters in atrial flutter4 and by using both diagnostic and ablation catheters in several supraventricular tachycardias (SVT)6 and atrial fibrillation (AF)7 cases. There may be concerns that the application of the non-fluoroscopic catheter visualization (NFCV) technology may increase procedural risks in the absence of the catheter shaft visualization and catheter localization that is solely based on the location of the catheter tip. It was demonstrated that the complication rate is equal or even lower to procedures performed with conventional tools14. This could be explained by a limitation of conventional procedures: only in a certain percentage of the procedure catheters will be &#8220;visible&#8221;. This changed by application of NFCV technology since catheters will be visible during the entire procedure on this virtual biplanar view.
In this protocol, we perform an ablation of atrial fibrillation in a patient with paroxysmal, drug-refractory and highly symptomatic atrial fibrillation. The goal of this protocol is to achieve the same endpoints as in a conventional procedure, i.e., isolation of all pulmonary veins with proven bi-directional block, and to reduce fluoroscopy exposure for the patient by &#62;90% as compared to conventional settings via the additional use of the NFCV technology.

<table><tbody><tr><td>MediGuide System</td><td>SJM</td><td>MG1000</td><td>Non fluoroscopic mapping system</td></tr><tr><td>Patient Reference Sensor (PRS) Patch</td><td>SJM</td><td>H700071</td><td>Reference sensor</td></tr><tr><td>Livewire&amp;trade; Diagnostic Catheter MediGuide Enabled&amp;trade;</td><td>SJM</td><td>D402058</td><td>diagnostic catheter</td></tr><tr><td>Agilis Nxt steerable introducers 71 cm small curle</td><td>SJM</td><td>408309</td><td>steerable sheath</td></tr><tr><td>BRK transseptal needle and stainless steel stylet</td><td>SJM</td><td>408314</td><td>transseptal needle</td></tr><tr><td>EnSite Velocity patch set</td><td>SJM</td><td>100003331</td><td>3D mapping tools</td></tr><tr><td>Safire BLU</td><td>SJM</td><td>A088087</td><td>Ablation catheter</td></tr><tr><td>Sensitherm</td><td>SJM</td><td>26155ST</td><td>thermoprobe</td></tr><tr><td>Siemens Artis</td><td>Siemens</td><td>x</td><td>X Ray biplanar</td></tr><tr><td>Ensite Velocity v. 2.1</td><td>SJM</td><td>x</td><td>3D mapping system</td></tr><tr><td>Ampere generator</td><td>SJM</td><td>H700494</td><td>RF generator</td></tr><tr><td>Ampere Remote control</td><td>SJM</td><td>H700490</td><td>Remote control for generator</td></tr><tr><td>Cool point</td><td>SJM</td><td>IBI-89003</td><td>Irrigation pump</td></tr><tr><td>Cool point tubing set</td><td>SJM</td><td>85785</td><td>Tubing set</td></tr></tbody></table>

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.

This procedure typically lasts 2-2.5 hr. The patients are under deep analog-sedation, meaning that they are sleeping, receiving analgesics but breathe spontaneously. If all endpoints including bi-directional block in all pulmonary veins, healthy left atrial tissue, and non-inducibility of atrial fibrillation or atrial flutter are achieved, patients have about a 75% probability of freedom from atrial fibrillation recurrence after 12 months. If the left atrium has fibrotic tissue with low voltage areas (see Figure 2), the chances of permanent freedom from arrhythmias decrease compared to patients with healthy left atrial tissue (see Figure 3). Typically, patients can be discharged 24 hr after the procedure. In the first 4-6 weeks after the ablation procedure, short episodes of atrial arrhythmias can occur and are frequent. After 6 weeks, the likely outcomes of the ablation procedure are evident. In most cases, all medical anti-arrhythmic treatments are discontinued on the day of the ablation procedure. Oral anticoagulation is mandatory and needs to be continued after the ablation procedure irrespective of the individual&#8217;s stroke risk for at least 3 months.
<img alt="Figure 1" src="/files/ftp_upload/52606/52606fig1.jpg" /> 
Figure 1: Ablation of atrial fibrillation using NFCV technology. Left and middle: catheter visualization using the NFCV technology: ablation catheter (red tip) in the left superior pulmonary vein (LSPV, blue marker). Right: the same setting displayed in the 3D mapping system. Ablation catheter (green halo) placed in the left superior pulmonary vein close to the ridge to the left atrial appendage. Esophageal temperature probe posterior to the left atrium (green catheter). <a href="https://www.jove.com/files/ftp_upload/52606/52606fig1highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/52606/52606fig2.jpg" /> 
Figure 2: Voltage map of a &#8220;diseased&#8221; left atrium. 3D reconstructed CT with low-voltage areas at the posterior wall of the left atrium and in the mitral isthmus region indicating areas of previous ablation. <a href="https://www.jove.com/files/ftp_upload/52606/52606fig2highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/52606/52606fig3.jpg" /> 
Figure 3: Voltage map of a &#8220;healthy&#8221; left atrium. 3D reconstructed CT model of a left atrium. A color-coded voltage map is shown with purple for healthy tissue (electrograms &#62;0.5 mV) and grey for scar tissue (electrograms &#60;0.2 mV). Electrogram amplitudes &#62;0.2 mV and &#60;0.5 mV are displayed in yellow, red, and blue. <a href="https://www.jove.com/files/ftp_upload/52606/52606fig3highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Video 1: Principle of NFCV. In the beginning of the procedure, 2 short cine loops (3 sec each) are recorded and are used as the dynamic background for catheter visualization. Specially-designed catheters with miniaturized sensors at the tip are inserted in the patient and visualized by the NFCV system. <a href="https://www.jove.com/files/ftp_upload/52606/Video1.mp4" target="_blank">Please click here to view this video.</a>

Watch this Scientific Journal Video about Non-fluoroscopic Catheter Tracking for Fluoroscopy Reduction in Interventional Electrophysiology at JoVE.com

Non-fluoroscopic Catheter Tracking for Fluoroscopy Reduction in Interventional Electrophysiology

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 ...

non-fluoroscopic-catheter-tracking-for-fluoroscopy-reduction

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JoVE Journal

Medicine

13.3K Views.  University of Leipzig. 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.

Video: Non-fluoroscopic Catheter Tracking for Fluoroscopy Reduction in Interventional Electrophysiology

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 ...

Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging

X-ray fluoroscopy-guided endovascular procedures have several significant limitations, including difficult catheter navigation and use of ionizing radiation, which can potentially be overcome using a magnetically steerable catheter under MR guidance.
	The main goal of this work is to develop a microcatheter whose tip can be remotely controlled using the magnetic field of the MR scanner. This protocol aims to describe the procedures for applying current to the microcoil-tipped microcatheter to produce consistent and controllable deflections.
	A microcoil was fabricated using laser lathe lithography onto a polyimide-tipped endovascular catheter. In vitro testing was performed in a waterbath and vessel phantom under the guidance of a 1.5-T MR system using steady-state free precession (SSFP) sequencing. Various amounts of current were applied to the coils of the microcatheter to produce measureable tip deflections and navigate in vascular phantoms.
	The development of this device provides a platform for future testing and opportunity to revolutionize the endovascular interventional MRI environment.

Current applied to an endovascular microcatheter with microcoil tip made by laser lathe lithography can achieve controllable deflections under magnetic resonance (MR) guidance, which may improve speed and efficacy of navigation of vasculature during various endovascular procedures.

X-ray fluoroscopy-guided  endovascular procedures have several significant limitations, including  difficult catheter navigation and use of ionizing ...

Bioengineering

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 ...

Three-Dimensional Ultrasonic Needle Tip Tracking with a Fiber-Optic Ultrasound Receiver

Ultrasound is frequently used for guiding minimally invasive procedures, but visualizing medical devices is often challenging with this imaging modality. When visualization is lost, the medical device can cause trauma to critical tissue structures. Here, a method to track the needle tip during ultrasound image-guided procedures is presented. This method involves the use of a fiber-optic ultrasound receiver that is affixed within the cannula of a medical needle to communicate ultrasonically with the external ultrasound probe. This custom probe comprises a central transducer element array and side element arrays. In addition to conventional two-dimensional (2D) B-mode ultrasound imaging provided by the central array, three-dimensional (3D) needle tip tracking is provided by the side arrays. For B-mode ultrasound imaging, a standard transmit-receive sequence with electronic beamforming is performed. For ultrasonic tracking, Golay-coded ultrasound transmissions from the 4 side arrays are received by the hydrophone sensor, and subsequently the received signals are decoded to identify the needle tip&#39;s spatial location with respect to the ultrasound imaging probe. As a preliminary validation of this method, insertions of the needle/hydrophone pair were performed in clinically realistic contexts. This novel ultrasound imaging/tracking method is compatible with current clinical workflow, and it provides reliable device tracking during in-plane and out-of-plane needle insertions.

Accurate and efficient visualization of invasive medical devices is extremely important in many ultrasound-guided minimally invasive procedures. Here, a method for localizing the spatial position of a needle tip relative to the ultrasound imaging probe is presented.

Ultrasound is frequently used for guiding minimally invasive procedures, but visualizing medical devices is often challenging with this imaging modality. ...

Engineering

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.

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 ...

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 ...

Improved Registration of 3D CT Angiography with X-ray Fluoroscopy for Image Fusion During Transcatheter Aortic Valve Implantation

The fusion of 3D anatomical models derived from high-fidelity pre-interventional computed tomography angiography (CTA), and x-ray (XR) fluoroscopy to facilitate anatomical guidance is of huge interest for complex cardiac interventions like TAVI procedures with cerebral protection. Co-registration of CTA and XR has been introduced either based on additional intraoperative non-/contrast-enhanced cone-beam computed tomography (CBCT) or two separate aortograms. With the related increase of radiation exposure and/or contrast agent (CA) dose, a potential additional risk for the patient is introduced. Here, we propose a modified co-registration approach making use of arteriograms of the iliofemoral arteries, routinely performed during the femoral puncture and sheath introduction. On-the-fly refinement of the co-registration during the on-going procedure enables accurate co-registration without any additional angiograms, thus reducing CA, XR dose and procedure time, while simultaneously improving operator confidence and procedure safety.

The aim of this study was to improve the co-registration for image fusion (IF) of pre-interventional CT data with real-time x-ray (XR) fluoroscopy during transfemoral transcatheter aortic valve implantation (TAVI).

The fusion of 3D anatomical models derived from high-fidelity pre-interventional computed tomography angiography (CTA), and x-ray (XR) fluoroscopy to ...

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 ...

Reduction of Radiation Exposure during Endovascular Treatment of Peripheral Arterial Disease Combining Fiber Optic RealShape Technology and Intravascular Ultrasound

Vascular surgeons and interventional radiologists face chronic exposure to low-dose radiation during endovascular procedures, which may impact their health in the long term due to their stochastic effects. The presented case shows the feasibility and efficacy of combining Fiber Optic RealShape (FORS) technology and intravascular ultrasound (IVUS) to reduce operator exposure during the endovascular treatment of obstructive peripheral arterial disease (PAD). 
FORS technology enables real-time, three-dimensional visualization of the full shape of guidewires and catheters, embedded with optical fibers that use laser light instead of fluoroscopy. Hereby, radiation exposure is reduced, and spatial perception is improved while navigating during endovascular procedures. IVUS has the capacity to optimally define vessel dimensions. Combining FORS and IVUS in a patient with iliac in-stent restenosis, as shown in this case report, enables passage of the stenosis and pre- and post-percutaneous transluminal angioplasty (PTA) plaque assessment (diameter improvement and morphology), with a minimum dose of radiation and zero contrast agent. The aim of this article is to describe the method of combining FORS and IVUS stepwise, to show the potential of merging both techniques in view of reducing radiation exposure and improving navigation tasks and treatment success during the endovascular procedure for the treatment of PAD.

Described here is a stepwise method of combining Fiber Optic RealShape technology and intravascular ultrasound to show the potential of merging both techniques, in view of the reduction of radiation exposure and improvement of navigation tasks and treatment success during an endovascular procedure for the treatment of peripheral arterial disease.

Vascular surgeons and interventional radiologists face chronic exposure to low-dose radiation during endovascular procedures, which may impact their ...

Non-fluoroscopic Catheter Tracking for Fluoroscopy Reduction in Interventional Electrophysiology

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