Name: remote magnetic navigation for accurate, real-time catheter positioning and ablation in cardiac electrophysiology procedures
Uploaded: 2013-04-21T14:00:00
Duration: 9 min 13 s
Description: Watch this Scientific Journal Video about Remote Magnetic Navigation for Accurate, Real-time Catheter Positioning and Ablation in Cardiac Electrophysiology Procedures at JoVE.com

Supported in part by Magnetecs Inc. (Inglewood, California, USA) in collaboration with the Comunidad de Madrid and La Paz University Hospital. We thank Iv&aacute;n Filgueiras-Rama and Jaime Palomo-Cousido for their help in the illustration of the figures and video editing.

Patients who underwent ablation of a right or left atrium flutter substrate were included (Table 1). The presence of decompensated or severe systemic disease, thrombus within the left atrium, renal failure, age &lt;18 years, body mass index &gt;40 and pregnancy were the exclusion criteria. This protocol is part of the initial safety and feasibility protocol approved by the Institution Research and Ethics Committee. No atrial fibrillation procedures were included in this protocol. All patients gave informed consent. 
1. Description of the Robotic Magnetic Navigation System
The Catheter Guidance Control and Imaging (CGCI) system employs eight powerful electromagnets to produce a highly agile magnetic field (to 0.16 Tesla) within an effective control area optimized to focus and contain the magnetic field almost entirely within the magnetic chamber. The magnetic chamber operates silently, has no moving parts and cools the electromagnet coils with non-toxic mineral oil. Current-regulated amplifiers provide the power to the magnetic chamber coils. The system produces magnetic fields 10 to 20 times less in intensity than Magnetic Resonance Imaging and no magnetic fields are generated when it is not in magnetic guidance mode. The magnetic field generators provide torque and force for moving, positioning and directing the tip of a catheter equipped with three permanent magnet pellets attached to its distal end. 
The Robotic system includes an Operation Console, the CGCI Controller computer and a motorized linear catheter advancement mechanism. The system uses a standard 3-axis joystick, which is used to rotate the magnetic field and manually advance or retract the catheter. A 3D Controller is used to push the catheter in any screen-oriented direction. The X-Ray C-Arm may be rotated or extracted at the Operation Console using the X-Ray Dialog. The Operation Console unifies the display of the CGCI system, electroanatomical mapping system, EP recording system, intracardiac ultrasound (ICE), and X-Ray. It allows the direct keyboard and mouse control over the electroanatomical mapping system and EP recording system. Typically, the center screen is used for the electroanatomical mapping system screen and the CGCI overlay graphics. 
2. Patient's Preparation
 Admit the patient to the hospital the same day or the day before the procedure. Overnight fasting state is required. 
<ol>
 <li>Position the patient on the operation table, where the nursing staff cannulates a peripheral intravenous catheter before the procedure.</li>
 <li>Outside of the magnetic chamber, the medical staff obtains right and left vein femoral access under local anesthesia with lidocaine. Place sheath introducers into the right and left femoral veins. We recommend guiding left atrium substrates using intracardiac echocardiography, which probe is introduced through a 9 French (Fr) left femoral vein sheath and positioned into the right atrium. </li>
 <li>For left atrium substrates, administer an initial intravenous bolus and repeated doses of heparin to maintain an activated clotting time of 250-300 s.</li>
 <li>Administer an initial bolus of 2 mg of midazolam followed by continuous intravenous propofol sedation and intermittent intravenous bolus of morphine hydrochloride during the procedure. </li>
</ol>
3. Conventional Electrophysiological Study
<ol>
 <li>Position standard catheters through the femoral sheath introducers into the right cardiac chambers for conventional diagnostic electrophysiological study. Use fluoroscopy guidance during manually positioning.</li>
 <li>Position a decapolar catheter into the coronary sinus and a screw-in catheter in the right atrial septum. </li>
 <li>Introduce a special steerable sheath with 3 electrodes along its distal end through the right femoral vein (Figure 1A) and place it in the inferior vena cava or the lower right atrium. </li>
 <li>Introduce a 7 Fr magnetized catheter into the cardiac chambers through the special sheath (Figure 1A, 1B). Next, perform conventional work up of the arrhythmia mechanism. </li>
 <li>If necessary (e.g. left atrium flutter mechanism), trans-septal access to the left atrium is achieved using a trans-septal sheath and continuous ICE monitoring. For left atrial flutter procedures also place a multipolar catheter into the left atrium through the trans-septal puncture. </li>
</ol>
4. Preparing for Remote Navigation. Catheter, Sheath, and Catheter Advancement Mechanism Assembly 
<ol>
 <li>The motorized linear catheter advancement mechanism consists of a sterilizable wheel drive gearbox and a motor base. It also includes a disposable sheath clip and leg mount (Figure 2A). The device adds or removes catheter slack.</li>
 <li>Mount the sheath in the clip and insert the catheter into the sheath, and manually advance it into the right/left atrium. The latter is confirmed by the mapping system and fluoroscopy. For left atrial substrates position the sheath in the right atrium in close proximity to the interatrial septum.</li>
 <li>Next, place catheter's shaft between the rollers of the wheel drive gearbox by pulling back on the thumb lever.</li>
 <li>The X-Ray C-Arm is moved to its operational position within the magnetic chamber. Patient's table is now advanced to localize the thorax within the magnetic field. </li>
 <li>The operator leaves the operation room and takes control from the operation console. </li>
 <li>The Magnetic catheter and the special sheath with electrodes are now shown on the center screen. All CGCI and electroanatomical mapping system operational functions are available at the CGCI operation Console.</li>
</ol>
 5. Remote Navigation and Mapping 
<ol>
 <li>Perform catheter contact calibration of the electrical coupling index system. Maximum and minimum contact values are set up on the control panel.</li>
 <li>Full integration with the electroanatomical mapping system and a closed-loop servo system allow remote navigation and 3D geometrical reconstruction of the right/left cardiac chambers, which allows the procedure to continue with minimal X-ray exposure. </li>
 <li>Use a right hand 3D Controller to steer the catheter to specific sites within the right/left atrium by changing the direction of the magnetic field (Figure 2B). A yellow magnetic arrow indicates the direction of the magnetic field. Use a left hand 3-axis joystick to control the amount of catheter slack (Figure 2C). The motorized device placed at the patient's leg allows the addition and retraction of catheter slack (Figure 2A). </li>
 <li>Rapid changes in the magnetic field magnitude, direction, and gradient yield push/pull and/or torque (bend) movements in the distal portion of the catheter. Real-time remote navigation is assessed based on field vector adjustments and subsequent response in the tip of the catheter. A magnetic icon displays the coil power values as colors. Green indicates a strong positive field, and red indicates a strong negative field (Figure 3). </li>
 <li>The catheter tip is aligned parallel to the vector direction of the magnetic flux density. The magnetic field gradient generated for force control of the catheter is up to 0.7T/meter, with a maximal perpendicular force exerted of 25 g. </li>
 <li>Perform geometrical point acquisitions from the 4 poles of the magnetized catheter while slowly moving the catheter all around the atrial chambers. A 3D EAM reconstruction can be obtained after few minutes (Figure 3A, 3B).</li>
 <li>Remote navigation with the steerable sheath positioned in the right atrium allows reaching the right inferior pulmonary vein by either directly deflecting the catheter upon crossing the interatrial septum or after making a loop in the opposite wall and then pointing the catheter towards the right inferior pulmonary vein. </li>
 <li>Generate activation, voltage and first post-pacing interval maps to characterize the reentrant circuit (Figure 4A, 4B). Identify ablation targets and localize them on the 3D geometry. </li>
</ol>
6. Ablation. Manual and Automated Catheter Positioning in the Target Sites
<ol>
 <li>In Automated Magnetic Guidance mode, the operator can automatically guide the catheter to specific targets by double-clicking on an electroanatomical mapping system label. This represents an essential feature to create remote and automatic ablation lines. </li>
 <li>For each individual target and with the CGCI system operating in the automated mode, drive the catheter to the target points (Figure 4C). In Automated mode, the system displays a targeting dialog. This indicates the intended target, range, time and targeting search status.</li>
 <li>Accuracy to automatically position the catheter on the target is also measured by the distance of the final location of the catheter to the initial manual positioning. The distance is measured in mm and considered significant if larger than 3 mm. Catheter navigation accuracy requires using the field-scaling tool of the electroanatomical mapping system. </li>
 <li>Manual intervention of an automatic search is possible by using the joystick or 3D Controller. </li>
 <li>To terminate the arrhythmia deliver radiofrequency energy to specific sites labeled as target points, either manually or automatically guided. The arrhythmia terminates and sinus rhythm is restored upon interruption of the reentrant circuit (Figure 4C, 4D). No re-induction by fast atrial pacing confirms the elimination of the arrhythmia. </li>
</ol>
The safety of the CGCI system is evaluated for each one of the experimental steps.

<ol>
	<li>Evans, G. T., 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=The+Percutaneous+Cardiac+Mapping+and+Ablation+Registry:+final+summary+of+results.">The Percutaneous Cardiac Mapping and Ablation Registry: final summary of results.</a> Pacing Clin. Electrophysiol. 11, 1621-1626 (1988).</li><li>Cappato, 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=Updated+worldwide+survey+on+the+methods,+efficacy,+and+safety+of+catheter+ablation+for+human+atrial+fibrillation.">Updated worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation.</a> Circ. Arrhythm. Electrophysiol. 3, 32-38 (2010).</li><li>Lafuente-Lafuente, C., Mouly, S., Longas-Tejero, M. A., Mahe, I., Bergmann, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antiarrhythmic+drugs+for+maintaining+sinus+rhythm+after+cardioversion+of+atrial+fibrillation:+a+systematic+review+of+randomized+controlled+trials.">Antiarrhythmic drugs for maintaining sinus rhythm after cardioversion of atrial fibrillation: a systematic review of randomized controlled trials.</a> Arch. Intern. Med. 166, 719-728 (2006).</li><li>Reddy, V. 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=Catheter+ablation+of+atrial+fibrillation+without+the+use+of+fluoroscopy.">Catheter ablation of atrial fibrillation without the use of fluoroscopy.</a> Heart Rhythm. 7, 1644-1653 (2010).</li><li>Knackstedt, C., Schauerte, P., Kirchhof, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electro-anatomic+mapping+systems+in+arrhythmias.">Electro-anatomic mapping systems in arrhythmias.</a> Europace. 10, iii28-iii34 (2008).</li><li>Merino, J. L., Guzman, G., Fernandez-Cuadrado, J. <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+guided+by+computed+tomography.">Atrial fibrillation ablation guided by computed tomography.</a> Rev. Esp. Cardiol. 62, 13133308 (2009).</li><li>Merino, J. L., Refoyo, E., Peinado, R., Cuesta, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+representation+of+multielectrode+ablation+catheters+by+integration+of+computed+tomographic+geometry+with+three-dimensional+electroanatomic+mapping+of+left+atrium+and+pulmonary+veins.">Real-time representation of multielectrode ablation catheters by integration of computed tomographic geometry with three-dimensional electroanatomic mapping of left atrium and pulmonary veins.</a> Heart Rhythm. 5, 628-629 (2008).</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=Computed+tomography+model-based+treatment+of+atrial+fibrillation+and+atrial+macro-re-entrant+tachycardia.">Computed tomography model-based treatment of atrial fibrillation and atrial macro-re-entrant tachycardia.</a> Europace. 10, 939-948 (2008).</li><li>Ernst, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+and+robotic+navigation+for+catheter+ablation:+"joystick+ablation".">Magnetic and robotic navigation for catheter ablation: "joystick ablation".</a> J. Interv. Card. Electrophysiol. 23, 41-44 (2008).</li><li>Nguyen, B. L., Merino, J. L., Gang, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remote+Navigation+for+Ablation+Procedures+-+A+New+Step+Forward+in+the+Treatment+of+Cardiac+Arrhythmias.">Remote Navigation for Ablation Procedures - A New Step Forward in the Treatment of Cardiac Arrhythmias.</a> European Cardiology. 6, 50-56 (2010).</li><li>Schmidt, B., 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=Remote+navigation+systems+in+electrophysiology.">Remote navigation systems in electrophysiology.</a> Europace. 10, iii57-iii61 (2008).</li><li>Al-Ahmad, A., Grossman, J. D., Wang, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+experience+with+a+computerized+robotically+controlled+catheter+system.">Early experience with a computerized robotically controlled catheter system.</a> J. Interv. Card. Electrophysiol. 12 (3), 199-202 (2005).</li><li>Ray, I. B., 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+with+a+novel+remote-guided+magnetic+catheter+navigation+system+for+left+ventricular+scar+mapping+and+ablation+in+a+porcine+model+of+healed+myocardial+infarction.">Initial experience with a novel remote-guided magnetic catheter navigation system for left ventricular scar mapping and ablation in a porcine model of healed myocardial infarction.</a> J. Cardiovasc. Electrophysiol. 18, 520-525 (2007).</li><li>Ernst, 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=Initial+experience+with+remote+catheter+ablation+using+a+novel+magnetic+navigation+system:+magnetic+remote+catheter+ablation.">Initial experience with remote catheter ablation using a novel magnetic navigation system: magnetic remote catheter ablation.</a> Circulation. 109, 1472-1475 (2004).</li><li>Nguyen, B. L., Farkas, L., Marx, B., 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=.">.</a> Heart Rhythm Society's 30th Annual Scientific Sessions. , (2009).</li><li>Nguyen, B. L., Merino, J. L., Gang, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remote+Navigation+for+Ablation+Procedures+-+A+New+Step+Forward+in+the+Treatment+of+Cardiac+Arrhythmias.">Remote Navigation for Ablation Procedures - A New Step Forward in the Treatment of Cardiac Arrhythmias.</a> European Cardiology. 6, 50-56 (2010).</li><li>Gang, E. 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=Dynamically+shaped+magnetic+fields:+initial+animal+validation+of+a+new+remote+electrophysiology+catheter+guidance+and+control+system.">Dynamically shaped magnetic fields: initial animal validation of a new remote electrophysiology catheter guidance and control system.</a> Circ. Arrhythm. Electrophysiol. 4, 770-777 (2011).</li><li>Bernabei, M. A., Ugarte, R. C., Martin, D. T., 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=.">.</a> Heart Rhythm Society's 30th Annual Scientific Sessions. , (2009).</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, 2407-2411 (2008).</li><li>Hlivak, 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=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, 534-540 (2011).</li></ol>

Dr. Jos&eacute; L. Merino received grants for clinical research from Magnetecs Inc. and Boston Scientific. Dr. Jos&eacute; L. Merino served as a speaker for St. Jude Medical. Dr. Gang and Yehoshua Shachar have equity interest in Magnetecs Corp.

This is the first clinical report using the CGCI remote navigation system. It shows important technical features that might facilitate both navigation and ablation in right and left atrial substrates. The system may potentially overcome some of the limitations of the former magnetic-based Niobe system.10 Thus, endocardial contact force and navigation inside the cardiac chambers may substantially improve by increasing the strength of the magnetic field magnitude up to 0.16 Tesla compared with 0.08 Tesla in the Niobe system. Continuous and rapid shaping and reshaping of the magnetic field, rather than moving external magnets to change the magnetic field,13,14 provides instantaneously transmitted changes to the tip of the magnetized catheter leading to almost real&#x2010;time remote navigation. In automated mode the CGCI system also provides a true closed-loop servo system that has the ability to keep the catheter tip on a desired anatomic target by continuously adjusting the direction and intensity of the magnetic fields.17 
The Sensei system, based on steerable sheaths manipulated within the heart by a mechanical robotic arm, allows real-time catheter movements.12 However, the use of mechanical forces to drive the catheter does not represent a technological advance over manual manipulation. Initial reports using the Sensei system had raised the concern of higher rate of cardiac tamponade than conventional manual radiofrequency delivery,18,19 which might have been related to remote manipulation of the stiff steerable Artisan catheter (Hansen Medical, Mountain View, CA, USA). Further experience and introduction of a special feature of the system to indirectly estimate catheter contact force on the tissue (IntelliSense) have shown that tamponade rates are not superior to conventional manual approach and may be more related to different temperature and power radiofrequency settings.20 
The CGCI system does not require a lab with specific magnetic isolation since the magnetic field is highly focused on patient&#x2019;s torso. In addition, the electrophysiology room can be used either as a conventional electrophysiology lab or as a magnetic lab by moving patient's table from its regular position towards the magnetic chamber. The latter can be done either manually or by remote control. Although no major complications have been present in this initial experience, in case of serious complications, such as pericardial effusion and tamponade, it would be possible to remove the patient from the magnetic chamber in &asymp;15 sec.
General demerits such as lack of real-time contact force monitoring or lesion visualization still apply to the CGCI system. Combining robotic navigation with real-time contact force catheters and direct visualization of the atrial cavities may be a future feasible approach to increase long-term success of ablation lesions and decrease the risk of complications. To date, experimental data using the CGCI system in pigs have demonstrated reproducible navigation and accurate and rapid catheter positioning on the selected ablation targets within the atrial chambers.17 Once the ablation target is localized, the system has the ability to navigate the catheter tip to the selected target despite the cardiac motion and anatomical irregularities. Furthermore, necropsy studies in the same animals revealed that the majority of radiofrequency lesions were transmural.17 In this first report in humans the system also shows reproducible navigation and accurate and rapid catheter positioning on the selected ablation targets within the right or left atrial chambers. The use of rapid magnetic field adjustments might enhance catheter tip stability and result in fewer radiofrequency applications as well as fewer major complications. Although the results and follow up in this initial experience are encouraging, future large and randomized clinical trials in patients undergoing complex catheter-guided ablation procedures are needed to demonstrate these potential benefits.

Catheter ablation of cardiac arrhythmias has become an effective treatment for different types of cardiac arrhythmias.1,2 Antiarrhythmic drugs have limited efficacy and often need to be withdrawn due to secondary effects or pro-arrhythmia.3 Thus, ablation is the only chance for a definitive treatment in many patients. Ablation procedures require moving catheters inside the vascular system and cardiac chambers to further identify the arrhythmia substrate before ablation. Proper catheter manipulation requires a skilled electrophysiologist working under fluoroscopic guidance. This may result in significant X-ray exposure, which is a risk for both patients and medical staff. In the last two decades, different navigation systems able to create electro-anatomical maps (EAM) have led to a decrease in X-ray exposure4 and to a better understanding of the substrate of cardiac arrhythmias.5-8 However, moving and placing catheters into specific regions of the heart still requires manual guidance, which makes these procedures highly dependent on operator skills. In addition, the constant beating of the heart makes stability one of the main problems of radiofrequency delivery in certain target cardiac regions. New remote navigation systems have been recently developed with the objective of overcoming such limitations and allowing the operators to be away from the X-ray source while they are moving the catheters inside the cardiovascular system.9-11 Two remote navigation systems are currently commercially available; the robotic catheter control system (Sensei system, Hansen Medical)12 and the magnetic catheter navigation system (Niobe system, Stereotaxis).13,14 The former is based on two steerable sheaths, through which any conventional catheter can be introduced for further manipulation via a pull-wire mechanism by a robotic arm fixed at a standard fluoroscopy table. The second system is based on two permanent magnets positioned on each side of the patient's body to create a uniform magnetic field. Special catheters with magnets affixed to their distal end can be navigated within the cardiac chambers by changing the orientation of the external magnetic fields. Shortcomings such as safety and similar to manual navigation or weak tissue contact force and lack of real time catheter response are present in Sensei and Niobe, respectively. 
In this report, we describe the features and potential ablation capabilities of a recently developed navigation system, the Catheter Guidance, Control and Imaging (CGCI).15,16

<table border="1">
<tbody>
 <tr>
 <td>Name of Reagent/ Equipment</td>
 <td>Company</td>
 <td>Catalog Number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>Radiofocus Introducer II 7 Fr.</td>
 <td>Terumo</td>
 <td>RS*R70N10MQ</td>
 <td></td>
 </tr>
 <tr>
 <td>Radiofocus Introducer II 6 Fr.</td>
 <td>Terumo</td>
 <td>RS*R60N10MQ</td>
 <td></td>
 </tr>
 <tr>
 <td>Avanti+ Introducer 9 Fr.</td>
 <td>Cordis, Johnson &amp; Johnson</td>
 <td>504-609X</td>
 <td></td>
 </tr>
 <tr>
 <td>Pecutaneous Transeptal Catheter Introducer Set 8 Fr.</td>
 <td>Medtronic</td>
 <td>008591</td>
 <td></td>
 </tr>
 <tr>
 <td>Brockenbrough Curved Needle</td>
 <td>Medtronic</td>
 <td>003994</td>
 <td></td>
 </tr>
 <tr>
 <td>Percutaneuos Transeptal Catheter Introducer Agilis ES</td>
 <td>St. Jude Medical</td>
 <td>3271521</td>
 <td></td>
 </tr>
 <tr>
 <td>BRK Transeptal Curved Needle</td>
 <td>St. Jude Medical</td>
 <td>407205;</td>
 <td></td>
 </tr>
 <tr>
 <td>Extension Set</td>
 <td>Sendal</td>
 <td>L-303/100</td>
 <td></td>
 </tr>
 <tr>
 <td>Extension Tube (25 cm)</td>
 <td>Iberhospitex S.A</td>
 <td>0044402</td>
 <td></td>
 </tr>
 <tr>
 <td>BD Eclipse Needle 25G x 5/8 (0.5 mm x 16 mm)</td>
 <td>BD</td>
 <td>305760</td>
 <td></td>
 </tr>
 <tr>
 <td>BD Eclipse Needle 21G x 1 1/2 TW (0.8 mm x 40 mm)</td>
 <td>BD</td>
 <td>305895</td>
 <td></td>
 </tr>
 <tr>
 <td>Surgical Gloves Sterile</td>
 <td>Semperit Technische Produkte Gesellschaft m. b. H. Division Sempermed</td>
 <td>826054720</td>
 <td></td>
 </tr>
 <tr>
 <td>Adult Cannula with 2.1 m Tubing</td>
 <td>Wolfram Droh GmbH</td>
 <td>MDRNC-03N</td>
 <td></td>
 </tr>
 <tr>
 <td>Oxygen Mask</td>
 <td>Carburos Medica Grupo Air Products</td>
 <td>75098</td>
 <td></td>
 </tr>
 <tr>
 <td>Saline</td>
 <td>Baxter S.L.</td>
 <td>PE1324</td>
 <td></td>
 </tr>
 <tr>
 <td>Saline </td>
 <td>Laboratorios Grifols</td>
 <td>3033986</td>
 <td></td>
 </tr>
 <tr>
 <td>Sterile Disposable Scalpel</td>
 <td>Sovereign </td>
 <td>D16390</td>
 <td></td>
 </tr>
 <tr>
 <td>I.V. Set for Gravity Infusion</td>
 <td>Sendal</td>
 <td>NT-820-ELL180</td>
 <td></td>
 </tr>
 <tr>
 <td>Sterile Banded Bag</td>
 <td>Barrier</td>
 <td>705845</td>
 <td></td>
 </tr>
 <tr>
 <td>Sterile Gauzes</td>
 <td>Ortopedia y Cirug&iacute;a, S.L.</td>
 <td>0323</td>
 <td></td>
 </tr>
 <tr>
 <td>Sterile Syringe</td>
 <td>BD Plastipak</td>
 <td>302188</td>
 <td></td>
 </tr>
 <tr>
 <td>Infusion Set. Anti-Siphon Valve 15 &mu;m Filter</td>
 <td>Alaris</td>
 <td>273-002</td>
 <td></td>
 </tr>
 <tr>
 <td>Infusion Pump (x4)</td>
 <td>CardinalHealth</td>
 <td>25042ESD1</td>
 <td></td>
 </tr>
 <tr>
 <td>Povidone-iodine (antiseptic for topical application) </td>
 <td>Lainco, S.A.</td>
 <td>619791.2 EFP</td>
 <td></td>
 </tr>
 <tr>
 <td>Morfine Hydrochloride 1%</td>
 <td>B. Braun</td>
 <td>451062</td>
 <td></td>
 </tr>
 <tr>
 <td>Propofol </td>
 <td>Fresenius Kani</td>
 <td>600514</td>
 <td></td>
 </tr>
 <tr>
 <td>Heparin</td>
 <td>Hospira Productos Farmac&eacute;uticos y Hospitalarios, S.L.</td>
 <td>Q63004</td>
 <td></td>
 </tr>
 <tr>
 <td>Lidocaine 1%</td>
 <td>B. Braun</td>
 <td>645598</td>
 <td></td>
 </tr>
 <tr>
 <td>Midazolam</td>
 <td>B. Braun</td>
 <td>602567</td>
 <td></td>
 </tr>
 <tr>
 <td>Iodixanol Injection 320 mgI/mL</td>
 <td>GE Healthcare</td>
 <td>687251.2</td>
 <td></td>
 </tr>
 <tr>
 <td>Pre-gelled Electrosurgical Plate</td>
 <td>Blayco</td>
 <td>2125-5</td>
 <td></td>
 </tr>
 <tr>
 <td>Single Patient Use ECG Electrodes</td>
 <td>Ambu</td>
 <td>SP-00-S/50</td>
 <td></td>
 </tr>
 <tr>
 <td>Irrigated Magnetic Navigation Catheter MagnoFlush Gold Tip 4 mm.</td>
 <td>MedFact Engineering GmbH</td>
 <td>100-002</td>
 <td></td>
 </tr>
 <tr>
 <td>Screw-in Catheter. Temporary Transcenous Pacing Lead System</td>
 <td>Medtronic</td>
 <td>6416-200</td>
 <td></td>
 </tr>
 <tr>
 <td>Extension Cable</td>
 <td>Medtronic</td>
 <td>9670560</td>
 <td></td>
 </tr>
 <tr>
 <td>Extension Cable (Number of pins 10) (x2)</td>
 <td>Bard Electrophysiology</td>
 <td>560004A</td>
 <td></td>
 </tr>
 <tr>
 <td>Extension Cable (Number of pins 4)</td>
 <td>Bard Electrophysiology</td>
 <td>560002P</td>
 <td></td>
 </tr>
 <tr>
 <td>Extension Cable </td>
 <td>St. Jude Medical</td>
 <td>ESI-42-04644-001</td>
 <td></td>
 </tr>
 <tr>
 <td>Extension Cable </td>
 <td>St. Jude Medical</td>
 <td>SJM 100011418</td>
 <td></td>
 </tr>
 <tr>
 <td>Connection Cable from IBI-Generator to MedFact RF-Ablation Catheter</td>
 <td>MedFact Engineering GmbH</td>
 <td>100-013</td>
 <td></td>
 </tr>
 <tr>
 <td>Decapolar Catheter Bard Viking 6F Josephson 115 cm</td>
 <td>Bard Electrophysiology</td>
 <td>400034</td>
 <td></td>
 </tr>
 <tr>
 <td>Multipolar (24 poles) Woven Diagnostic Electrode Catheter</td>
 <td>Bard Electrophysiology</td>
 <td>6FMC00798</td>
 <td></td>
 </tr>
 <tr>
 <td>Ensite NavX System (Version 8.1)</td>
 <td>St. Jude Medical</td>
 <td>100022310</td>
 <td></td>
 </tr>
 <tr>
 <td>Ensite System Patient Interface Unit</td>
 <td>St. Jude Medical</td>
 <td>75-05049-001</td>
 <td></td>
 </tr>
 <tr>
 <td>Ensite NavX Surface Electrode Kit</td>
 <td>St. Jude Medical</td>
 <td>EN0010-002</td>
 <td></td>
 </tr>
 <tr>
 <td>Irrigation Qiona Pump</td>
 <td>MollerMedical GmbH. Biotronik SE &amp; Co.</td>
 <td>363270</td>
 <td></td>
 </tr>
 <tr>
 <td>External Defibrillator/Monitor LifePaK12</td>
 <td>Medtronic </td>
 <td>073-20719-10</td>
 <td></td>
 </tr>
 <tr>
 <td>X-Ray C-Arm Ziehm Vision2 FD Vario</td>
 <td>Ziehm Imaging</td>
 <td>TS04_001a</td>
 <td></td>
 </tr>
 <tr>
 <td>Cardiac Ablation Generator. Software Version V3.0</td>
 <td>Irvine Biomedical, Inc. A St. Jude Medical Company</td>
 <td>IBI-1500T11</td>
 <td></td>
 </tr>
 <tr>
 <td>IBI-1500T11 Remote Control</td>
 <td>Irvine Biomedical, Inc. A St. Jude Medical Company</td>
 <td>85524</td>
 <td></td>
 </tr>
 <tr>
 <td>Dispersive Electrode Filter </td>
 <td>St. Jude Medical</td>
 <td>3183417</td>
 <td></td>
 </tr>
 <tr>
 <td>Stimulus Generator Unit for EPS 320 Cardiac Stimulator Models</td>
 <td>Micropace Pty. Ltd.</td>
 <td>MP3008</td>
 <td></td>
 </tr>
 <tr>
 <td>Lab System Pro EP Recording System</td>
 <td>Bard Electrophysiology</td>
 <td></td>
 <td>The system includes several components provided by the company</td>
 </tr>
 <tr>
 <td>NEC Multisync LCD Screen</td>
 <td>Micropace Pty. Ltd.</td>
 <td>3892D240</td>
 <td></td>
 </tr>
 <tr>
 <td>Whole Blood Microcoagulation System. Hemochron Jr.</td>
 <td>International Technidyne Corporation (ITC)</td>
 <td>HJ7023</td>
 <td></td>
 </tr>
 <tr>
 <td>Cuvettes for ACT for performance on the Hemochron</td>
 <td>International Technidyne Corporation (ITC)</td>
 <td>FB5033</td>
 <td></td>
 </tr>
 <tr>
 <td>Ultrasound Catheter ViewFlex PLUS 9 Fr.</td>
 <td>St. Jude Medical</td>
 <td>VF-PM</td>
 <td></td>
 </tr>
 <tr>
 <td>ViewFlex Catheter Interface Module</td>
 <td>St. Jude Medical</td>
 <td>20-1783-0000</td>
 <td></td>
 </tr>
 <tr>
 <td>HD11 Digital Ultrasound Machine</td>
 <td>Philips</td>
 <td>US30975460</td>
 <td></td>
 </tr>
 <tr>
 <td>CGCI, Magnetic Navigation System, Catheter Guidance, Control and Imaging System</td>
 <td>Magnetecs Corporation</td>
 <td></td>
 <td>The system includes several components provided by the company. Further support and information may be obtained at: 
 <ul>
 	<li> EU Service and Technical Support: support@magnetecs.com </li>
 <li>USA Service and Technical Support: support@magnetecs.com USA Tel. 310-649-9000</li>
 </ul>
 </td>
 </tr>
 </tbody>
</table>

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 new remote magnetic navigation system allows real-time remote catheter navigation inside the right and left atrial chambers, either in the operator or automated mode. The latter is obtained after almost instantaneous field vector adjustments of direction and intensity of torque, bending, rotating, and field gradient for axial push-pull movement (See video for illustration).
The system allows arrhythmia termination upon radiofrequency delivery in the absence of major complications (cardiac tamponade, pulmonary embolism or major hemorrhages) during this initial ablation experience (Figure 4).
The automated catheter remote navigation is highly reproducible, accurate, and rapid to position and keeps the catheter tip on the desired target. Based on five initial experimental procedures the navigation was 95.7 % reproducible, the average accuracy was 1.9&plusmn;0.9 mm and the average time to reach the target was 23.28&plusmn;14.8 sec. We considered nine targets in the right atrium (coronary sinus, 2 locations at the high right atrium, 3 locations at the tricuspid annulus, His, superior vena cava and inferior vena cava), nine targets in the left atrium (2 locations at the left atrial appendage, 3 locations at the mitral annulus and one location at each one of the pulmonary veins), six target sites in the right ventricle (2 locations at the right ventricular outflow tract, apex, right ventricle free wall, inferior wall and septum) and five more targets in the left ventricle (apex, anterior wall, lateral wall, septum and left ventricular outflow tract). Neither time, accuracy nor reproducibility to reach a target site were significantly different between chambers and targets.
<table border="1">
<tbody>
 <tr>
 <td>Type of Arrhythmia</td>
 <td>Atrial Substrate</td>
 <td>Type of ablation</td>
 <td>Acute Success</td>
 <td>Procedure-derived Complications***</td>
 <td>Recurrences</td>
 </tr>
 <tr>
 <td rowspan="3">LA flutter (n=3)</td>
 <td>Right PVs</td>
 <td>Posterior wall line</td>
 <td>Yes</td>
 <td>None</td>
 <td>No. 6 months FU</td>
 </tr>
 <tr>
 <td>Left PVs</td>
 <td>Roof line</td>
 <td>Yes*</td>
 <td>None</td>
 <td>No. 4 months FU</td>
 </tr>
 <tr>
 <td>Inferior lateral wall</td>
 <td>Focal RF delivery</td>
 <td>Yes**</td>
 <td>None</td>
 <td>No. 3 months FU</td>
 </tr>
 <tr>
 <td rowspan="2">RA flutter (N=2)</td>
 <td rowspan="2">Counterclockwise cavo-tricuspidIsthmus dependent RA flutter</td>
 <td rowspan="2">Cavo-tricuspidIsthmus line</td>
 <td>Yes</td>
 <td>None</td>
 <td>No. 10 months FU</td>
 </tr>
 <tr>
 <td>Yes</td>
 <td>None</td>
 <td>No. 11 months FU</td>
 </tr>
 </tbody>
</table>
Table 1. Atrial substrates and ablation results using the CGCI system. FU: follow up. LA: left atrium. RF: radiofrequency. RA: right atrium. PV: pulmonary vein.*Induction of 2 more non sustained and non clinical LA flutter morphologies.**LA flutter no longer re-inducible. Induction of atrial fibrillation at the end of the study.***The presence of pericardial effusion was assessed by intracardiac echocardiography throughout the procedure.
<img src="/files/ftp_upload/3658/3658fig1.jpg" alt="Figure 1" /> 
Figure 1. Agilis ES sheath (A) and MedFact magnetized and irrigated gold tip catheter (B) used for geometrical reconstruction and ablation in the right and left atrial chambers.
<img src="/files/ftp_upload/3658/3658fig2.jpg" alt="Figure 2" /> 
Figure 2. Components for remote navigation. A, motorized linear catheter advancement mechanism with a sterilizable wheel drive gearbox and a motor base. It includes a disposable sheath clip and leg mount. The magnetized catheter is inserted into the sheath and manually advanced into the right/left atrium. B, right hand 3D Controller used to steer the catheter to specific sites within the atrial chambers by changing the direction of the magnetic field. C, left hand 3-axis joystick to control the amount of catheter slack.
<img src="/files/ftp_upload/3658/3658fig3.jpg" alt="Figure 3" /> 
Figure 3. 3D electro-anatomical mapping geometry of the left atrium and pulmonary veins. A, geometrical point acquisitions within the left atrium using the magnetized catheter, which is represented with the white tip and the overlaying yellow arrow. The magnetic icon displays the coil power values as colors: green indicates a strong positive field, and red indicates a strong negative field. In blue a catheter into the coronary sinus. In red a screw-in catheter positioned in the right atrial septum. The multipolar catheter is shown in yellow. B, final view of the 3D anatomical reconstruction of the left atrium. MA; mitral annulus.
<img src="/files/ftp_upload/3658/3658fig4.jpg" alt="Figure 4"/> 
Figure 4. Interruption of a left atrial flutter circuit around the right pulmonary veins after automatically guided radiofrequency energy delivered to specific sites in the posterior wall of the left atrium. A, voltage map shows a dense scar in the posterior wall of the left atrium (grey color). B, first post-pacing interval map generated to characterize the reentrant circuit, which is localized around the right pulmonary veins (posterior view is shown). White and red indicate first post-pacing intervals &lt;30 msec. C and D, in automated mode the catheter is driven to the target points and the arrhythmia terminates after completing a line in the posterior wall of the left atrium, which interrupts the reentrant circuit. <a href="https://www.jove.com/files/ftp_upload/3658/3658fig4large.jpg" target="_blank">Click here to view larger figure</a>.

Watch this Scientific Journal Video about Remote Magnetic Navigation for Accurate, Real-time Catheter Positioning and Ablation in Cardiac Electrophysiology Procedures at JoVE.com

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

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 ...

remote-magnetic-navigation-for-accurate-real-time-catheter

Research

JoVE Journal

Medicine

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 ...

Cardiac Magnetic Resonance Imaging at 7 Tesla

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher magnetic field strengths and potentially provides improved signal contrast and spatial resolution. While promising results have been achieved, ultra-high field CMR is challenging due to energy deposition constraints and physical phenomena such as transmission field non-uniformities and magnetic field inhomogeneities. In addition, the magneto-hydrodynamic effect renders the synchronization of the data acquisition with the cardiac motion difficult. The challenges are currently addressed by explorations into novel magnetic resonance technology. If all impediments can be overcome, ultra-high field CMR may generate new opportunities for functional CMR, myocardial tissue characterization, microstructure imaging or metabolic imaging. Recognizing this potential, we show that multi-channel radio frequency (RF) coil technology tailored for CMR at 7 Tesla together with higher order B0 shimming and a backup signal for cardiac triggering facilitates high fidelity functional CMR. With the proposed setup, cardiac chamber quantification can be accomplished in examination times similar to those achieved at lower field strengths. To share this experience and to support the dissemination of this expertise, this work describes our setup and protocol tailored for functional CMR at 7 Tesla.

The sensitivity gain inherent to ultrahigh field magnetic resonance holds promise for high spatial resolution imaging of the heart. Here, we describe a protocol customized for functional cardiovascular magnetic resonance (CMR) at 7 Tesla using an advanced multi-channel radio-frequency coil, magnetic field shimming and a triggering concept.

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher ...

Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System

Since its invention in the late 19th century, the Langendorff ex vivo heart perfusion system continues to be a relevant tool for studying a broad spectrum of physiological, biochemical, morphological, and pharmacological parameters in centrally denervated hearts. Here, we describe a setup for the modulation of the intracardiac autonomic nervous system and the assessment of its influence on basic electrophysiology, arrhythmogenesis, and cyclic adenosine monophosphate (cAMP) dynamics. The intracardiac autonomic nervous system is modulated by the mechanical dissection of atrial fat pads-in which murine ganglia are located mainly&#8212;or by the usage of global as well as targeted pharmacological interventions. An octapolar electrophysiological catheter is introduced into the right atrium and the right ventricle, and epicardial-placed multi-electrode arrays (MEA) for high-resolution mapping are used to determine cardiac electrophysiology and arrhythmogenesis. F&#246;rster resonance energy transfer (FRET) imaging is performed for the real-time monitoring of cAMP levels in different cardiac regions. Neuromorphology is studied by means of antibody-based staining of whole hearts using neuronal markers to guide the identification and modulation of specific targets of the intracardiac autonomic nervous system in the performed studies. The ex vivo Langendorff setup allows for a high number of reproducible experiments in a short time. Nevertheless, the partly open nature of the setup (e.g., during MEA measurements) makes constant temperature control difficult and should be kept to a minimum. This described method makes it possible to analyze and modulate the intracardiac autonomic nervous system in decentralized hearts.

Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System

Here, we present a protocol for the modulation of the intracardiac autonomic nervous system and the assessment of its influence on basic electrophysiology, arrhythmogenesis, and cAMP dynamics using an ex vivo Langendorff setup.

Since its invention in the late 19th century, the Langendorff ex vivo heart perfusion system continues to be a relevant tool for studying a broad spectrum ...

Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The appearance of a mass on certain magnetic resonance (MR) sequences can help differentiate a thrombus from competing diagnoses such as a tumor. T1 and T2 signal characteristics of a thrombus are related to the evolution of hemoglobin properties. A thrombus typically does not enhance following contrast administration, which also helps differentiation from a tumor. We also highlight the emerging role of T1 mapping in the evaluation of a thrombus, which can add another level of support in diagnosis. Prior to any CMR exam, patient screening and interviews are critical to ensure safety and to optimize patient comfort. Effective communication during the exam between the technologist and the patient promotes proper breath holding technique and higher quality images. Volumetric post processing and structured reporting are helpful to ensure that the radiologist answers the ordering services&#39; question and communicates these results effectively. Optimal pre-MR safety evaluation, CMR exam execution, and post exam processing and reporting allow for delivery of high quality radiological service in the evaluation of a suspected cardiac thrombus.

The goal of this article is to describe how cardiac magnetic resonance can be used for the evaluation and diagnosis of a suspected cardiac thrombus. The method presented will describe data acquisition as well as the pre-procedure and post-procedure protocol.

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The ...

Real-Time Assessment of Spinal Cord Microperfusion in a Porcine Model of Ischemia/Reperfusion

Spinal cord injury is a devastating complication of aortic repair. Despite developments for the prevention and treatment of spinal cord injury, its incidence is still considerably high and therefore, influences patient outcome. Microcirculation plays a key role in tissue perfusion and oxygen supply and is often dissociated from macrohemodynamics. Thus, direct evaluation of spinal cord microcirculation is essential for the development of microcirculation-targeted therapies and the evaluation of existing approaches in regard to spinal cord microcirculation. However, most of the methods do not provide real-time assessment of spinal cord microcirculation. The aim of this study is to describe a standardized protocol for real-time spinal cord microcirculatory evaluation using laser-Doppler needle probes directly inserted in the spinal cord. We used a porcine model of ischemia/reperfusion to induce deterioration of the spinal cord microcirculation. In addition, a fluorescent microsphere injection technique was used. Initially, animals were anesthetized and mechanically ventilated. Thereafter, laser-Doppler needle probe insertion was performed, followed by the placement of cerebrospinal fluid drainage. A median sternotomy was performed for exposure of the descending aorta to perform aortic cross-clamping. Ischemia/reperfusion was induced by supra-celiac aortic cross-clamping for a total of 48 min, followed by reperfusion and hemodynamic stabilization. Laser-Doppler Flux was performed in parallel with macrohemodynamic evaluation. In addition, automated cerebrospinal fluid drainage was used to maintain a stable cerebrospinal pressure. After completion of the protocol, animals were sacrificed, and the spinal cord was harvested for histopathological and microsphere analysis. The protocol reveals the feasibility of spinal cord microperfusion measurements using laser-Doppler probes and shows a marked decrease during ischemia as well as recovery after reperfusion. Results showed comparable behavior to fluorescent microsphere evaluation. In conclusion, this new protocol might provide a useful large animal model for future studies using real-time spinal cord microperfusion assessment in ischemia/reperfusion conditions.

Spinal cord microcirculation plays a pivotal role in spinal cord injury. Most methods do not allow real-time assessment of spinal cord microcirculation, which is essential for the development of microcirculation-targeted therapies. Here, we propose a protocol using Laser-Doppler-Flow Needle probes in a large animal model of ischemia/reperfusion.

Spinal cord injury is a devastating complication of aortic repair. Despite developments for the prevention and treatment of spinal cord injury, its ...

Real-Time Dynamic Navigation System for the Precise Quad-Zygomatic Implant Placement in a Patient with a Severely Atrophic Maxilla

Zygomatic implants (ZIs) are an ideal way to address cases of a severely atrophic edentulous maxilla and maxilla defects because they replace extensive bone augmentation and shorten the treatment cycle. However, there are risks associated with the placement of ZIs, such as penetration of the orbital cavity or infra-temporal fossa. Furthermore, the placement of multiple ZIs makes this surgery risky and more difficult to perform. Potential intraoperative complications are extremely dangerous and may cause irreparable losses. Here, we describe a practical, feasible, and reproducible protocol for a real-time surgical navigation system for precisely placing quad-zygomatic implants in the severely atrophic maxilla of patients with residual bone that does not meet the requirements of conventional implants. Hundreds of patients have received ZIs at our department based on this protocol. The clinical outcomes have been satisfactory, the intraoperative and postoperative complications have been low, and the accuracy indicated by infusion of the designed image and postoperative three-dimensional image has been high. This method should be utilized during the entire surgical procedure to ensure ZI placement safety.

Here, we present a protocol to achieve precise quad-zygomatic implant placement in patients with severely atrophic maxilla using a real-time dynamic navigation system.

Zygomatic implants (ZIs) are an ideal way to address cases of a severely atrophic edentulous maxilla and maxilla defects because they replace extensive ...

Tissue Preparation Techniques for Contrast-Enhanced Micro Computed Tomography Imaging of Large Mammalian Cardiac Models with Chronic Disease

Structural remodeling is a common consequence of chronic pathological stresses imposed on the heart. Understanding the architectural and compositional properties of diseased tissue is critical to determine their interactions with arrhythmic behavior. Microscale tissue remodeling, below the clinical resolution, is emerging as an important source of lethal arrhythmia, with high prevalence in young adults. Challenges remain in obtaining high imaging contrast at sufficient microscale resolution for preclinical models, such as large mammalian whole hearts. Moreover, tissue composition-selective contrast enhancement for three-dimensional high-resolution imaging is still lacking. Non-destructive imaging using micro-computed tomography shows promise for high-resolution imaging. The objective was to alleviate sufferance from X-ray over attenuation in large biological samples. Hearts were extracted from healthy pigs (N = 2), and sheep (N = 2) with either induced chronic myocardial infarction and fibrotic scar formation or induced chronic atrial fibrillation. Excised hearts were perfused with: a saline solution supplemented with a calcium ion quenching agent and a vasodilator, ethanol in serial dehydration, and hexamethyldisilizane under vacuum. The latter reinforced the heart structure during air-drying for 1 week. Collagen-dominant tissue was selectively bound by an X-ray contrast-enhancing agent, phosphomolybdic acid. Tissue conformation was stable in air, permitting long-duration microcomputed tomography acquisitions to obtain high-resolution (isotropic 20.7 &#181;m) images. Optimal contrast agent loading by diffusion showed selective contrast enhancement of the epithelial layer and sub-endocardial Purkinje fibers in healthy pig ventricles. Atrial fibrillation (AF) hearts showed enhanced contrast accumulation in the posterior walls and appendages of the atria, attributed to greater collagen content. Myocardial infarction hearts showed increased contrast selectively in regions of cardiac fibrosis, which enabled the identification of interweaving surviving myocardial muscle fibers. Contrast-enhanced air-dried tissue preparations enabled microscale imaging of the intact large mammalian heart and selective contrast enhancement of underlying disease constituents.

Here, we present a protocol to obtain high resolution micro computed tomography images of healthy and pathological large mammalian whole hearts with collagen-selective contrast enhancement.

Structural remodeling is a common consequence of chronic pathological stresses imposed on the heart. Understanding the architectural and compositional ...

Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice

Regular physical exercise is a major contributor to cardiovascular health, influencing various metabolic as well as electrophysiological processes. However, in certain cardiac diseases such as inherited arrhythmia syndromes, e.g., arrhythmogenic cardiomyopathy (ACM) or myocarditis, physical exercise may have negative effects on the heart leading to a proarrhythmogenic substrate production. Currently, the underlying molecular mechanisms of exercise-related proarrhythmogenic remodeling are largely unknown, thus it remains unclear which frequency, duration, and intensity of exercise can be considered safe in the context of disease(s).
The proposed method allows to study proarrhythmic/antiarrhythmic effects of physical exercise by combining treadmill training with real-time monitoring of the ECG. Implantable telemetry devices are used to continuously record the ECG of freely moving mice over a period of up to 3 months both at rest and during treadmill training. Data acquisition software with its analysis modules is used to analyze basic ECG parameters such as heart rate, P wave duration, PR interval, QRS interval, or QT duration at rest, during and after training. Furthermore, heart rate variability (HRV) parameters and occurrence of arrhythmias are evaluated. In brief, this manuscript describes a step-by-step approach to experimentally explore exercise induced effects on cardiac electrophysiology, including potential proarrhythmogenic remodeling in mouse models.

Electrocardiogram (ECG) is the key variable to understanding cardiac electrophysiology. Physical exercise has beneficial effects but may also be harmful in the context of cardiovascular diseases. This manuscript provides a method of recording real-time ECG during exercise, which can serve to investigate its effects on cardiac electrophysiology in mice.

Regular physical exercise is a major contributor to cardiovascular health, influencing various metabolic as well as electrophysiological processes. ...