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 border="0" cellpadding="0" cellspacing="0">
	<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&#8482; Diagnostic Catheter MediGuide Enabled&#8482;</td>
			<td>SJM</td>
			<td>D402058</td>
			<td>diagnostic catheter</td>
		</tr>
		<tr>
			<td>Agilis Nxt steerable introducers 71cm 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 ...

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13.2K 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 ...

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 ...

Dual-phase Cone-beam Computed Tomography to See, Reach, and Treat Hepatocellular Carcinoma during Drug-eluting Beads Transarterial Chemo-embolization

The advent of cone-beam computed tomography (CBCT) in the angiography suite has been revolutionary in interventional radiology. CBCT offers 3 dimensional&#160;(3D) diagnostic imaging in the interventional suite and can enhance minimally-invasive therapy beyond the limitations of 2D angiography alone. The role of CBCT has been recognized in transarterial chemo-embolization (TACE) treatment of hepatocellular carcinoma (HCC). The recent introduction of a CBCT technique: dual-phase CBCT (DP-CBCT) improves intra-arterial HCC treatment with drug-eluting beads (DEB-TACE). DP-CBCT can be used to localize liver tumors with the diagnostic accuracy of multi-phasic multidetector computed tomography (M-MDCT) and contrast enhanced magnetic resonance imaging (CE-MRI) (See the tumor), to guide intra-arterially guidewire and microcatheter to the desired location for selective therapy (Reach the tumor), and to evaluate treatment success during the procedure (Treat the tumor). The purpose of this manuscript is to illustrate how DP-CBCT is used in DEB-TACE to see, reach, and treat HCC.

Dual-phase cone-beam computed tomography (DP-CBCT) is a useful intraprocedural imaging technique for transarterial chemo-embolization treatment with drug-eluting beads of hepatocellular carcinoma. DP-CBCT has been used to perform three major steps in oncologic interventional radiology: tumor localization (see), navigation and intraprocedural catheter guidance (reach), and intraprocedural evaluation of treatment success (treat).

The advent of cone-beam computed tomography (CBCT) in the angiography suite has been revolutionary in interventional radiology. CBCT offers 3 ...

In vivo 19F MRI for Cell Tracking

In vivo 19F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. Here, we describe a general protocol for cell labeling, imaging, and image processing. The technique is applicable to various cell types and animal models, although here we focus on a typical mouse model for tracking murine immune cells. The most important issues for cell labeling are described, as these are relevant to all models. Similarly, key imaging parameters are listed, although the details will vary depending on the MRI system and the individual setup. Finally, we include an image processing protocol for quantification. Variations for this, and other parts of the protocol, are assessed in the Discussion section. Based on the detailed procedure described here, the user will need to adapt the protocol for each specific cell type, cell label, animal model, and imaging setup. Note that the protocol can also be adapted for human use, as long as clinical restrictions are met.

In vivo 19F MRI for Cell Tracking

We describe a general protocol for in vivo cell tracking using MRI in a mouse model with ex vivo labeled cells. A typical protocol for cell labeling, image acquisition processing and quantification is included.

In vivo 19F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. ...

The Supraclavicular Fossa Ultrasound View for Central Venous Catheter Placement and Catheter Change Over Guidewire

The supraclavicular fossa ultrasound view can be useful for central venous catheter (CVC) placement. Venipuncture of the internal jugular veins (IJV) or subclavian veins is performed with a micro-convex ultrasound probe, using a neonatal abdominal preset with a probe frequency of 10 Mhz at a depth of 10-12 cm. Following insertion of the guidewire into the vein, the probe is shifted to the right supraclavicular fossa to obtain a view of the superior vena cava (SVC), right pulmonary artery and ascending aorta. Under real-time ultrasound view, the guidewire and its J-tip is visualized and pushed forward to the lower SVC. Insertion depth is read from guidewire marks using central venous catheter. CVC is then inserted following skin and venous dilation. The supraclavicular fossa view is most suitable for right IJV CVC insertion. If other insertion sites are chosen the right supraclavicular fossa should be within the sterile field. Scanning of the IJVs, brachiocephalic veins and SVC can reveal significant thrombosis before venipuncture. Misplaced CVCs can be corrected with a change over guidewire technique under real-time ultrasound guidance. In conjunction with a diagnostic lung ultrasound scan, this technique has a potential to replace chest radiograph for confirmation of CVC tip position and exclusion of pneumothorax. Moreover, this view is of advantage in patients with a non-p-wave cardiac rhythm were an intra-cardiac electrocardiography (ECG) is not feasible for CVC tip position confirmation. Limitations of the method are lack of availability of a micro-convex probe and the need for training.

The overall goal is to enable clinicians to insert a central venous catheter under real-time ultrasound guidance via the right supraclavicular fossa view of the lower part of the superior vena cava. This view is useful for different catheter insertion sites, thrombosis detection before insertion and ultrasound guided correction of misplaced catheters.

The supraclavicular fossa ultrasound view can be useful for central venous catheter (CVC) placement. Venipuncture of the internal jugular veins (IJV) or ...

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 ...

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 ...

Development and Evaluation of 3D-Printed Cardiovascular Phantoms for Interventional Planning and Training

Catheter-based interventions are standard treatment options for cardiovascular pathologies. Therefore, patient-specific models could help training physicians&#39; wire-skills as well as improving planning of interventional procedures. The aim of this study was to develop a manufacturing process of patient-specific 3D-printed models for cardiovascular interventions.
To create a 3D-printed elastic phantom, different 3D-printing materials were compared to porcine biological tissues (i.e., aortic tissue) in terms of mechanical characteristics. A fitting material was selected based on comparative tensile tests and specific material thicknesses were defined. Anonymized contrast-enhanced CT-datasets were collected retrospectively. Patient-specific volumetric models were extracted from these datasets and subsequently 3D-printed. A pulsatile flow loop was constructed to simulate the intraluminal blood flow during interventions. Models&#39; suitability for clinical imaging was assessed by x-ray imaging, CT, 4D-MRI and (Doppler) ultrasonography. Contrast medium was used to enhance visibility in x-ray-based imaging. Different catheterization techniques were applied to evaluate the 3D-printed phantoms in physicians&#39; training as well as for pre-interventional therapy planning.
Printed models showed a high printing resolution (~30 &#181;m) and mechanical properties of the chosen material were comparable to physiological biomechanics. Physical and digital models showed high anatomical accuracy when compared to the underlying radiological dataset. Printed models were suitable for ultrasonic imaging as well as standard x-rays. Doppler ultrasonography and 4D-MRI displayed flow patterns and landmark characteristics (i.e., turbulence, wall shear stress) matching native data. In a catheter-based laboratory setting, patient-specific phantoms were easy to catheterize. Therapy planning and training of interventional procedures on challenging anatomies (e.g., congenital heart disease (CHD)) was possible.
Flexible patient-specific cardiovascular phantoms were 3D-printed, and the application of common clinical imaging techniques was possible. This new process is ideal as a training tool for catheter-based (electrophysiological) interventions and can be used in patient-specific therapy planning.

Here we present development of a mock circulation setup for multimodal therapy evaluation, pre-interventional planning, and physician-training on cardiovascular anatomies. With the application of patient-specific tomographic scans, this setup is ideal for therapeutic approaches, training, and education in individualized medicine.

Catheter-based interventions are standard treatment options for cardiovascular pathologies. Therefore, patient-specific models could help training ...

Interventional Diagnostic Procedure: A Practical Guide for the Assessment of Coronary Vascular Function

Approximately 40% of patients undergoing invasive coronary angiography for investigation of angina are found to have no obstructive coronary artery disease (ANOCA). Abnormal coronary function underlies coronary vasomotion syndromes including coronary endothelial dysfunction, microvascular angina, vasospastic angina, post-PCI angina and myocardial infarction with no obstructive coronary arteries (MINOCA). Each of these endotypes are distinct subgroups, characterized by specific disease mechanisms. Diagnostic criteria and linked therapy for these conditions are now established by expert consensus and clinical guidelines.
Coronary function tests are performed as an adjunctive interventional diagnostic procedure (IDP) in appropriately selected patients during coronary angiography. This aids differentiation of patients according to endotype. The IDP includes two distinct components: a diagnostic guidewire test and a pharmacological coronary reactivity test. The tests last approximately 5 minutes for the former and 10-15 minutes for the latter. Patient safety and staff education are key.
The diagnostic guidewire test measures parameters of coronary flow limitation (fractional flow reserve [FFR], coronary flow reserve [CFR], microvascular resistance [index of microvascular resistance (IMR)], basal resistance index, and vasodilator function [CFR, resistive reserve ratio (RRR)]).
The pharmacological coronary reactivity test measures the vasodilator potential and propensity to vasospasm of both the main coronary arteries and the micro-vessels. It involves intra-coronary infusion of acetylcholine and glyceryl trinitrate (GTN). Acetylcholine is not licensed for parenteral use and is therefore prescribed on a named-patient basis. Vasodilatation is the normal, expected response to infusion of physiological concentrations of acetylcholine. Vascular spasm represents an abnormal response, which supports the diagnosis of vasospastic angina.
The purpose of this practical guide is to provide information on the preparation and administration of the IDP in clinical practice. It discusses some key preparation and safety considerations, as well as tips for procedural success. The IDP supports stratified medicine for a personalized approach to health and wellbeing.

The purpose of this practical guide is to provide information on the preparation and administration of an interventional diagnostic procedure in clinical practice. It discusses some key preparation and safety considerations, as well as tips for procedural success.

Approximately 40% of patients undergoing invasive coronary angiography for investigation of angina are found to have no obstructive coronary artery ...

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 ...