The following protocol complies with the guidelines of the human research ethics committee of the department for internal medicine/cardiology of the Hietzing Hospital in Vienna.
1. Preliminary Measures
<ol>
	<li>Administer the patient for whom VT ablation is planned at the ward at least 2 days prior to the procedure.</li>
	<li>Acquire blood sampling, X-ray of the chest and transthoracic echo-cardiography. In case of known atrial fibrillation (persistent or paroxysmal), perform a transesophageal echocardiography one day prior to the procedure.</li>
	<li>On the day of VT ablation, discontinue oral anticoagulants (in case the patient takes some for atrial fibrillation or other co-morbidities requiring the use of oral anticoagulants) and administer i.v. antibiotics.</li>
</ol>
2. Patient Preparation During the Procedure
<ol>
	<li>Apply self-adhesive ECG electrodes for 12-lead ECG (on the front chest - see Supplementary Figure 1 - and extremities in a standard position) as well as surface patches, neutral electrode and a system reference electrode compatible with the designated 3D mapping system (see Table of Materials) and a neutral electrode for the ablation catheter in a standard position to the patient&#180;s skin (see also Supplementary Figure 2).</li>
	<li>Apply self-adhesive defibrillator patches to the patient&#180;s skin in the advised position (below the right clavicle and at the left ventricular apex) and switch on the defibrillator.</li>
	<li>Deactivate the tachycardia therapies of the ICD with the appropriate programmer, optionally deactivate all device functions that might interfere with the ablation current. 
	NOTE: Tachycardia therapies of the ICD will stay deactivated throughout the procedure. Guarantee close monitoring and consistent readiness of the external defibrillator.</li>
	<li>Use a pulse oximeter to monitor the oxygen saturation.</li>
	<li>Introduce a sheath via the left radial artery for invasive blood pressure monitoring, either via Seldinger technique6 or with an arterial puncture system with an integrated cannula (see Table of Materials).</li>
	<li>Disinfect patient&#180;s skin in both groins with 75% propanol (see Table of Materials) and cover the patient&#180;s body with a sterile cloth, sparing the groins. 
	NOTE: At this point, all persons entering the catheter laboratory and working in close proximity to the patient have to wear hoods and masks.</li>
</ol>
3. Groin Puncture and Catheter Positioning
<ol>
	<li>Apply local anesthesia (xylocaine) in both groins by subcutaneous injection and introduce a central venous catheter via the left femoral vein and 3 sheaths (5, 6 and 12 Fr) via the right femoral vein with Seldinger technique6.</li>
	<li>Place a quadripolar catheter in the right ventricular apex and an 8-polar steerable catheter in the coronary sinus by means of fluoroscopy (beam positions: AP, RAO 30&#176;, and LAO 60&#176;). 
	NOTE: As soon as the x-ray equipment is activated, all persons entering the catheter laboratory have to wear lead protection.</li>
	<li>Connect diagnostic catheters to the electrophysiology system and stimulator (see table of materials).</li>
	<li>Verify that the quadripolar catheter in the right ventricle has sufficient capture by stimulating with a cycle length of 600 ms (or less, if the patient is tachycardic) and look for the adequate response.</li>
	<li>Administer 5000 IU heparin via a venous sheath in the groin. Perform activated clotting time (ACT) measurements every half hour with an appropriate device (see Table of Materials, ACT goal: above 300 s).</li>
	<li>Introduce a long steerable sheath (see Table of Materials) via the right femoral vein into the right atrium of the heart and perform trans-septal puncture using an appropriate needle connected to a pressure sensor line (beam positions AP and LAO 90&#176; or RAO 20&#176; and LAO 50&#176; depending on the investigator). After puncturing the inter-atrial septum of the heart, disconnect the pressure sensor line and apply contrast agent via the needle to check the correct position inside the left atrium. Then advance the sheath over the dilator under fluoroscopy control and place the distal end of the long steerable sheath in the left atrium pointing towards the left ventricle.</li>
	<li>Initiate general anesthesia by administration of propofol and remifentanil.</li>
</ol>
4. Electro-anatomical Reconstruction of the Left Ventricle
<ol>
	<li>Introduce a multipolar mapping catheter (steerable 16 pole catheter, electrode spacing 3-3-3, electrode length 1 mm, see Table of Materials) in the left ventricle via the steerable sheath and collect anatomical and electrical data of the endocardial left ventricle using the 3D mapping system (see Table of Materials) and the multipolar catheter.</li>
	<li>Define voltage of ventricular signals as follows: scar area under 0.5 mV, low voltage area between 0.5 and 1.5 mV and normal voltage area above 1.5 mV. Be careful to take into consideration only ventricular beats of the same type: either intrinsic ventricular activation in sinus rhythm or stimulated ventricular beats if the patient is pacemaker-dependent. Do not use premature ventricular complexes. Use the morphology matching feature to sort out unwanted ventricular complexes (see Figure 1).</li>
	<li>Optionally, turn down the lower voltage limit to 0.2 mV to identify viable conducting tissue inside the scar (see&#160;Figure 2&#160;and&#160;3).</li>
	<li>Pay close attention to fractionated (ventricular activation with more than one component) and late (second ventricular activation clearly separated from the first ventricular activation on a given electrode) potentials and annotate them separately (e.g. with special tags, see Figure 4A).</li>
	<li>Optionally, pace from the right ventricle to clearly separate the late potential from the first ventricular activation (see Figure 4B).</li>
	<li>Remove the multipolar&#160;mapping catheter and introduce an irrigated tip ablation catheter with sensor (electrode spacing 2-2-2, see Table of Materials) connected to a cooling pump into the left ventricle. Complete the electroanatomical map with the ablation catheter by adding missing anatomy (collect electroanatomical points at places where the multipoloar catheter could not be placed) and verifying zones of high interest (i.e. zones with very fractionated and late potentials &#8212; tag those zones separately, see Figures 1-2).</li>
</ol>
5. Programmed Ventricular Stimulation (PVS)
<ol>
	<li>Perform PVS7 via the catheter in the right ventricular apex and the EP stimulator (see Table of Materials) using a predefined protocol of up to 9 steps or until a sustained VT is induced:
	<ol>
		<li>Begin with a 6-beat drive train (10 V over 2 ms) with 500 ms cycle length and add an extra-stimulus of 350 ms coupling interval after the last stimulus of the drive train. Then, after a pause of at least 5 s, repeat this maneuver by decrementing the coupling interval of the extra-stimulus every cycle by 10 ms until the refractory time of the right ventricle is reached.</li>
		<li>Then, add a second extra-stimulus (beginning with 350 ms coupling interval) and repeat the above-mentioned protocol until ventricular refractory time. Couple the first extra-stimulus with the following interval: refractory time plus 20-30 ms, as appropriate (make sure the first&#160;extra-stimulus captures the right ventricle).</li>
		<li>Reduce the drive train to 430 ms, then 370 ms and at last 330 ms and repeat the above-mentioned steps.</li>
		<li>At last, add a 3rd extra-stimulus to the drive train of 500 ms and repeat the above-mentioned protocol.</li>
		<li>Repeat the protocol in the right ventricular outflow tact (RVOT) if no sustained VT can be induced.</li>
		<li>Make sure that the external defibrillator is ready to deliver a shock at any time during the whole procedure, and re-check it before PVS.</li>
	</ol>
	</li>
	<li>In case a sustained monomorphic VT can be induced (the following also applies if VT occurs during mapping or ablation):
	<ol>
		<li>Create an activation map of the left ventricle using the 3 D mapping system (LAT-map: local activation time) if the VT is hemodynamically stable. Optionally, perform entrainment mapping.</li>
		<li>Stop the VT by overdrive stimulation via the catheter in the right ventricular apex or, if that fails, by external cardioversion/defibrillation, if the VT is hemodynamically unstable.</li>
		<li>Mark and annotate every VT that can be induced and compare them to spontaneously occurring VTs or use it for pace mapping.</li>
		<li>If no sustained VT can be induced, continue with substrate modification (point 6) in case of a well-defined scar in ischemic cardiomyopathy. However, without inducible VT at the beginning of the procedure, there is no clear endpoint and control of success of the ablation therapy.</li>
	</ol>
	</li>
</ol>
6. Catheter Ablation
<ol>
	<li>Start irrigated radio frequency ablation with 35 to 45 W using the ablation catheter. Optionally, use a contact force catheter that provides information on tissue contact. Apply energy per lesion until a force-time-integral of 450 gs. Encircle scar areas by ablation lesions. Then, ablate all previously mapped abnormal potentials (substrate modification). Match pace mapping in electrically interesting regions to previously marked VTs.</li>
	<li>Pay close attention to ablation catheter impedance (usually between 90 and 150 Ohm), catheter temperature (max. 43 &#176;C) and patient&#180;s blood pressure (compared to the initial value). Immediately stop ablation if impedance drops or rises substantially compared to the initial value.</li>
</ol>
7. Post Ablation
<ol>
	<li>After ablation, repeat PVS.
	<ol>
		<li>If ventricular arrhythmias can be induced, re-evaluate the substrate and continue ablation (see points 5 and&#160;6).</li>
		<li>If no arrhythmia can be induced, stop the procedure.</li>
	</ol>
	</li>
	<li>Stop general anesthesia (optionally an anesthesiologist takes care of general anesthesia and gradually discontinues all sedative agents at the end of the procedure).</li>
	<li>Remove all catheters and sheaths from the heart.</li>
	<li>Re-activate the tachycardia therapies of the ICD and restore all formerly de-activated functions.</li>
	<li>Perform transthoracic echocardiography to exclude pericardial effusion.</li>
	<li>Take a final ACT measurement and administer protamine, if appropriate.</li>
	<li>Remove the sheaths of the right groin and apply a compression bandage. The central venous catheter in the left groin remains.</li>
	<li>As soon as the patient is awake and extubated, bring him to the intensive care unit for further surveillance.</li>
</ol>

<ol>
	<li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+top+10+causes+of+death.">The top 10 causes of death.</a> Health Organization Organization. , (2007).</li><li>Poole, J. E., 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=Prognostic+importance+of+defibrillator+shocks+in+patients+with+heart+failure.">Prognostic importance of defibrillator shocks in patients with heart failure.</a> N. Engl. J. Med. 359 (10), 1009-1017 (2008).</li><li>Kamphuis, H. C., de Leeuw, J. R., Derksen, R., Hauer, R. N., Winnubst, 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=Implantable+cardioverter+defibrillator+recipients:+quality+of+life+in+recipients+with+and+without+ICD+shock+delivery:+a+prospective+study.">Implantable cardioverter defibrillator recipients: quality of life in recipients with and without ICD shock delivery: a prospective study.</a> Europace. 5 (4), 381-389 (2003).</li><li>Stevenson, W. G., 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=Irrigated+radiofrequency+catheter+ablation+guided+by+electroanatomic+mapping+for+recurrent+ventricular+tachycardia+after+myocardial+infarction:+the+multicenter+thermocool+ventricular+tachycardia+ablation+trial.">Irrigated radiofrequency catheter ablation guided by electroanatomic mapping for recurrent ventricular tachycardia after myocardial infarction: the multicenter thermocool ventricular tachycardia ablation trial.</a> Circulation. 118 (25), 2773-2782 (2008).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Task+Force+for+the+Management+of+Patients+with+Ventricular+Arrhythmias+and+the+Prevention+of+Sudden+Cardiac+Death+of+the+European+Society+of+Cardiology+(ESC).+2015+ESC+Guidelines+for+the+management+of+patients+with+ventricular+arrhythmias+and+the+prevention+of+sudden+cardiac+death.">The Task Force for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death of the European Society of Cardiology (ESC). 2015 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death.</a> Eur Heart. 36 (41), 2793-2867 (2015).</li><li>Seldinger, S. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Catheter+replacement+of+the+needle+in+percutaneous+arteriography;+a+new+technique.">Catheter replacement of the needle in percutaneous arteriography; a new technique.</a> Acta radiol. 39 (5), 368-376 (1953).</li><li>Kossaify, A., Refaat, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Programmed+ventricular+stimulation+-+indications+and+limitations:+a+comprehensive+update+and+review.">Programmed ventricular stimulation - indications and limitations: a comprehensive update and review.</a> Hellenic J Cardiol. 54, 39-46 (2013).</li><li>. Figures taken and modified from the user handbook of the EnSite Precision Cardiac Mapping System Available from: <a target="_blank" href="https://manuals.sjm.com">https://manuals.sjm.com</a> (2017)</li><li>Tsuchiya, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+mapping+of+cardiac+arrhythmias+-+string+of+pearls.">Three-dimensional mapping of cardiac arrhythmias - string of pearls.</a> Circ J. 76 (3), 572-581 (2012).</li><li>Cano, O., 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=Utility+of+high+density+multielectrode+mapping+during+ablation+of+scar-related+ventricular+tachycardia.">Utility of high density multielectrode mapping during ablation of scar-related ventricular tachycardia.</a> J Cardiovasc Electrophysiol. 28 (11), 1306-1315 (2017).</li><li>Schaeffer, 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=Characterization,+mapping+and+ablation+of+complex+atrial+tachycardia:+initial+experience+with+a+novel+method+of+ultra-high-density+3D+mapping.">Characterization, mapping and ablation of complex atrial tachycardia: initial experience with a novel method of ultra-high-density 3D mapping.</a> J Cardiovasc Electrophysiol. 27 (10), 1139-1150 (2016).</li><li>Latcu, D. G., 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=Selection+of+critical+isthmus+in+scar-related+atrial+tachycardia+using+a+new+automated+ultrahigh+resolution+mapping+system.">Selection of critical isthmus in scar-related atrial tachycardia using a new automated ultrahigh resolution mapping system.</a> Circ Arrhythm Electrophysiol. 10 (1), (2017).</li></ol>

The use of 3D mapping systems in complex electrophysiological procedures is a well-established method to acquire detailed and precise anatomical information and reduce radiation time and enables the creation of substrate and activation maps9. However, data acquisition can be challenging due to difficult catheter movement, especially in the left ventricle. Furthermore, point by point map acquisition takes a lot of time and thus prolongates the electrophysiological procedure. Wide electrode spacing at the tip of the mapping catheter reduces resolution and quality of the created map, critical signals may be overlooked. The use of a multipolar catheter for mapping of the ventricle solves the above-mentioned issues: several mapping points can be taken simultaneously; procedure time decreases. The narrow-spaced electrodes guarantee a very high resolution of the map, important signals are not so easily missed anymore.
Currently, there are 3 different 3D mapping systems available, all of them allowing the use of multipolar mapping catheters.
So far, one of them using a magnetic field is widely used, especially in VT ablation, due to its user-friendly handling and highly accurate electroanatomical reconstruction. A suitable mapping catheter, a 20-pole steerable catheter with narrow electrode spacing, can access even difficult anatomies due to its special configuration (star shape) and provides precise high density maps10.
A relatively new 3D mapping system also allows a very quick and precise acquisition of multiple mapping points by means of a 64-electrode mapping catheter with a basket shape11,12.
The 3D mapping system used in the protocol (see Table of Materials) combines impedance and magnetic field technology and thus allows precise navigation and accurate tracking of mapping and ablation catheters, either conventional or sensor enabled. The created electro-anatomical maps are highly accurate and don&#180;t need further post-processing compared with former versions of the mapping system. A huge advantage for accurate mapping is the morphology matching feature, which allows continuous comparison of QRS morphologies during map acquisition. The suitable 16-pole mapping catheter (see Table of Materials) allows the acquisition of multiple points simultaneously and makes possible high resolution and the detection of even small critical signals due to its narrow electrode spacing (3-3-3).
To further improve the quality of the map and identify critical potentials, we changed the low voltage range from 0.5-1.5 mV to 0.2-1.5 mV (to identify viable and conducting tissue inside the scar). Interestingly, most late potentials were detected in viable zones within the scar (see Figure&#160;1 and Figure 2).
By pacing from the catheter in the right ventricle, late potentials could clearly be separated from the first ventricular activation (see Figure 4B).
Despite the steerability of the 16-pole mapping catheter, we could not access all regions of the left ventricle. Those sites had to be addressed with the ablation catheter, which also has close electrode spacing (2-2-2), as well as a pressor sensor to guarantee adequate wall contact.
Despite all the above-mentioned advantages, the more sophisticated a method gets, the more prone it is to disturbances. Catheter noise can occur and make the interpretation of signals very difficult. Artifacts can simulate electrically interesting potentials and misguide the investigator. Multipolar catheters require more cables that can be damaged, the connection can be disturbed, troubleshooting costs time. 
Despite those disadvantages, multipolar catheters, if used correctly and by experienced investigators, are very useful for complex electrophysiological procedures and have a large potential in the future. Reduction of procedure time helps to prevent adverse events in these often very ill patients. The additional electrical information provided has to be interpreted carefully and along with other parameters available

Coronary artery disease and myocardial infarction remain major causes for morbidity and mortality in the industrialized world1. Myocardial scars after transmural infarction represent low voltage areas and thus zones of slow electrical conduction and facilitate the appearance and maintenance of macro-reentrant circuits. Ventricular tachycardias (VT) are responsible for repeat hospitalizations, painful shocks of implantable cardioverter defibrillators (ICD) and thus lessen quality of life and cause poor outcome2,3. Catheter ablation can reduce the occurrence of VT, especially in ischemic heart disease4, and should be considered in patients with ventricular arrhythmias and underlying structural heart disease in the presence of an ICD (class IIa B recommendation)5. In patients with structural heart disease with ventricular arrhythmias already suffering from ICD shocks, catheter ablation is recommended (class I B recommendation)5. However, catheter ablation is still a high-risk procedure, considering the often-poor state of health of concerned patients with mostly reduced left ventricular ejection fraction and multiple co-morbidities. Furthermore, the precise localization of scars and abnormal potential can be challenging but are critical for ablation success. The use of 3D mapping systems and multipolar catheters allow electro-anatomical high-density mapping and can considerably facilitate the acquisition of electrical information and thus improve the quality and validity of the 3D model and consequently enhance ablation success and patient outcome. So far, there are 3 different 3D mapping systems available, whereof one is commonly used for VT ablation. The following protocol describes an approach to endocardial ischemic VT ablation using a less common 3 D mapping system in the field of VT ablation and a multipolar catheter (see Table of Materials) for high-density electro-anatomical reconstruction.

<table><tbody><tr><td>NaVX EnSite Precision 3 D mapping system</td><td>Saint Jude Medical</td><td></td><td></td></tr><tr><td>EnSite Precision Surface Electrode Kit</td><td>St. Jude Medical</td><td>EN0020-P</td><td></td></tr><tr><td>Ampere RF Ablation generator&amp;nbsp;</td><td>St. Jude Medical</td><td>H700494</td><td></td></tr><tr><td>EP-4, Cardiac Stimulator</td><td>St. Jude Medical</td><td>EP-4I-4-110</td><td></td></tr><tr><td>LabSystem PRO EP recording system, v2.4a&amp;nbsp;</td><td>Boston Scientific</td><td></td><td></td></tr><tr><td>octapolar diagnostic catheter, EP-XT</td><td>Bard</td><td>200797</td><td>electrode spacing 2-10-2</td></tr><tr><td>supreme quadripolar diagnostic catheter</td><td>St. Jude Medical</td><td>401441</td><td>electrode spacing 5-5-5</td></tr><tr><td>Agilis NxT 8.5F, 71/91 cm steerable sheath, large curl</td><td>St. Jude Medical</td><td>G408324</td><td></td></tr><tr><td>BRK transseptal needle, 98 cm</td><td>St. Jude Medical</td><td>407206</td><td></td></tr><tr><td>Advisor HD Grid mapping catheter, sensor enabled</td><td>St. Jude Medical</td><td>D-AVHD-DF16</td><td>electrode spacing 3-3-3</td></tr><tr><td>quadripolar irrigated tip ablation catheter, TactiCath SE</td><td>St. Jude Medical</td><td>A-TCSE-F</td><td>electrode spacing 2-2-2 with pressure sensor</td></tr><tr><td>Cool Point pump for irrigated ablation</td><td>St. Jude Medical</td><td>IBI-89003</td><td></td></tr><tr><td>Cool Point tubing set</td><td>St. Jude Medical</td><td>85785</td><td></td></tr><tr><td>GEM PCL Plus Instrumentation laboratory</td><td>IL Werfen India Pvt. Ltd.</td><td></td><td>&amp;nbsp;activated clotting time measurement device</td></tr><tr><td>X-ray equipment</td><td>Philips</td><td></td><td></td></tr><tr><td>Heartstart XL defibrillator and associated patches</td><td>Philips</td><td></td><td></td></tr><tr><td>12 F Fast-Cath sheath</td><td>St. Jude Medical</td><td>406128</td><td></td></tr><tr><td>6 F sheath</td><td>Johnson-Johnson</td><td></td><td></td></tr><tr><td>5 F sheath</td><td>Johnson-Johnson</td><td></td><td></td></tr><tr><td>BD Floswitch&amp;trade;</td><td>Becton Dickinson</td><td></td><td></td></tr><tr><td>Isozid&amp;reg;-H gef&amp;auml;rbt</td><td>Novartis</td><td></td><td></td></tr></tbody></table>

ablation of ischemic ventricular tachycardia using a multipolar catheter and 3-dimensional mapping system for high-density electro-anatomical reconstruction

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

The protocol describes in detail catheter ablation of monomorphic ventricular tachycardia in a patient with ischemic heart disease after anterior myocardial infarction with occlusion of the proximal left anterior descendant artery. The patient suffered from multiple ICD shock deliveries. Transthoracic echocardiography showed a severely reduced systolic left ventricular function (ejection fraction 30%) with a large apex aneurysm. VT ablation was performed using a 3D mapping system (see Table of Materials) and a multipolar (16 pole) steerable mapping catheter (see Table of Materials, electrode size 1 mm, electrode spacing 3-3-3). Simultaneous acquisition of numerous mapping points allowed a rapid and precise electroanatomical reconstruction of the left ventricle (see Figures 1, 2 and 3). The close electrode spacing of the multipolar catheter made possible the detection of critical signals such as fragmented and late potentials. Additional pacing from the right ventricle clearly separated the late potential from the first ventricular activation and thus identified the mapped area as a zone of slow conduction and therefore of high importance regarding the occurrence and maintenance of ventricular arrhythmias (see Figure 4). Areas that could not be reached with the multipolar catheter where addressed with the ablation catheter (see Table of Materials), which also has a close electrode spacing of 2-2-2.
By means of all the above-mentioned mapping strategies, a very precise map could be generated, showing a scar area at the left ventricular apex and adjacent areas (see Figures 1, 2 and 3, scar area 54 cm2). However, mapping time could be limited to 27 min.
During programmed ventricular stimulation and ablation, a total of 4 VTs could be induced. One of them (see Supplementary&#160;Figure 3) could be entrained and successfully ablated at the lateral border zone of the scar. Additionally, substrate modification was performed by encircling the scar, ablating all late abnormal potentials and ablating sites of pace maps matching the induced VTs.
At the end of the procedure, no VT could be induced with the stimulation sequences that enhanced the VTs at the beginning of the procedure. Only a VT with presumably epicardial origin could be induced with very aggressive stimulation. We decided to stop the procedure at that point.
The described method helps to improve ablation success and patient outcome.
<img alt="Supplementary Figure 1" src="/files/ftp_upload/57234/57234supfig1.jpg" /> 
Supplementary Figure 1: ECG electrode position. The position of the surface ECG electrodes on the front chest (taken and adapted from the user handbook of the 3D mapping system8). <a href="/files/ftp_upload/57234/57234supfig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Supplementary Figure 2" src="/files/ftp_upload/57234/57234supfig2.jpg" /> 
Supplementary Figure 2: 3D mapping system patch position. The position of the EnSite Precision&#8482; patches on the body (taken and modified from the user handbook of the 3D mapping system8). <a href="/files/ftp_upload/57234/57234supfig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Supplementary Figure 3" src="/files/ftp_upload/57234/57234supfig3.jpg" /> 
Supplementary Figure 3: Clinical tachycardia. One of four induced ventricular tachycardias during the procedure, written with 50 mm/s, cycle length 440 ms. <a href="/files/ftp_upload/57234/57234supfig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57234/57234fig1.jpg" /> 
Figure 1: Voltage map range 0.5 to 1.5 mV. RAO (left side) and LAO (right side) projections of a voltage map of the endocardial left ventricle. Small yellow dots represent electro-anatomical mapping points. The voltage of ventricular signals is defined as scar below 0.5 mV (grey), the low voltage between 0.5 and 1.5 mV (from red to blue) and the normal voltage above 1.5 mV (purple, see the scale on the left side of the figure). Large green dots represent late potentials. <a href="/files/ftp_upload/57234/57234fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57234/57234fig2.jpg" /> 
Figure 2: Voltage map range 0.2 to 1.5 mV. RAO (left side) and LAO (right side) projections of the same voltage map, this time with a low voltage range between 0.2 and 1.5 mV. Note the now patchy still viable and thus conducting tissue inside the scar. Late potentials (green dots) are located those areas that presumably represent zones of slow conduction. <a href="/files/ftp_upload/57234/57234fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57234/57234fig3.jpg" /> 
Figure 3: Voltage map with ablation lesions. RAO (left side) and LAO (right side) projections of the voltage map of the endocardial left ventricle (low voltage range between 0.2 and 1.5 mV) including ablation lesions (large red dots). <a href="/files/ftp_upload/57234/57234fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57234/57234fig4v2.jpg" /> 
Figure 4: Intracardiac electrogram with late potentials. Intracardiac electrogram at a site where late potentials could be recorded. 12-lead ECG on top of the screen; RVAd: catheter in the right ventricular apex; Grid: multipolar catheter (16 poles); CS: 8-pole catheter in the coronary sinus. (A) in sinus rhythm. The late potential visible on the multipolar catheter (marked with the red arrow) is located directly after the first ventricular activation. (B) during RVA-stimulation at the same site. The late potential visible on the multipolar catheter (red arrow) is now clearly separated from the first ventricular activation.&#160;<a href="/files/ftp_upload/57234/57234fig4v2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Ablation of Ischemic Ventricular Tachycardia Using a Multipolar Catheter and 3-dimensional Mapping System for High-density Electro-anatomical Reconstruction a

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

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

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

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14.6K Views.  Hietzing Hospital. With the following protocol, we provide an approach to Ventricular Tachycardia (VT) ablation using high density mapping with a multipolar catheter and 3D mapping system enhancing the success of the procedure.

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

Multiparametric Optical Mapping of the Langendorff-perfused Rabbit Heart

Optical imaging and fluorescent probes have significantly advanced research methodology in the field of cardiac electrophysiology in ways that could not have been accomplished by other approaches1. With the use of the calcium- and voltage-sensitive dyes, optical mapping allows measurement of transmembrane action potentials and calcium transients with high spatial resolution without the physical contact with the tissue. This makes measurements of the cardiac electrical activity possible under many conditions where the use of electrodes is inconvenient or impossible1. For example, optical recordings provide accurate morphological changes of membrane potential during and immediately after stimulation and defibrillation, while conventional electrode techniques suffer from stimulus-induced artifacts during and after stimuli due to electrode polarization1. 
The Langendorff-perfused rabbit heart is one of the most studied models of human heart physiology and pathophysiology. Many types of arrhythmias observed clinically could be recapitulated in the rabbit heart model. It was shown that wave patterns in the rabbit heart during ventricular arrhythmias, determined by effective size of the heart and the wavelength of reentry, are very similar to that in the human heart2. It was also shown that critical aspects of excitation-contraction (EC) coupling in rabbit myocardium, such as the relative contribution of sarcoplasmic reticulum (SR), is very similar to human EC coupling3. Here we present the basic procedures of optical mapping experiments in Langendorff-perfused rabbit hearts, including the Langendorff perfusion system setup, the optical mapping systems setup, the isolation and cannulation of the heart, perfusion and dye-staining of the heart, excitation-contraction uncoupling, and collection of optical signals. These methods could be also applied to the heart from species other than rabbit with adjustments to flow rates, optics, solutions, etc.
Two optical mapping systems are described. The panoramic mapping system is used to map the entire epicardium of the rabbit heart4-7. This system provides a global view of the evolution of reentrant circuits during arrhythmogenesis and defibrillation, and has been used to study the mechanisms of arrhythmias and antiarrhythmia therapy8,9. The dual mapping system is used to map the action potential (AP) and calcium transient (CaT) simultaneously from the same field of view10-13. This approach has enhanced our understanding of the important role of calcium in the electrical alternans and the induction of arrhythmia14-16.

This article describes the basic procedures for conducting optical mapping experiments in the Langendorff-perfused rabbit heart using the panoramic imaging system, and the dual (voltage and calcium) imaging modality.

Optical imaging and fluorescent probes have significantly advanced research methodology in the field of cardiac electrophysiology in ways that could not ...

Bioengineering

High-Resolution Endocardial and Epicardial Optical Mapping in a Sheep Model of Stretch-Induced Atrial Fibrillation

Atrial fibrillation (AF) is a complex cardiac arrhythmia with high morbidity and mortality.1,2 It is the most common sustained cardiac rhythm disturbance seen in clinical practice and its prevalence is expected to increase in the coming years.3 Increased intra-atrial pressure and dilatation have been long recognized to lead to AF,1,4 which highlights the relevance of using animal models and stretch to study AF dynamics. Understanding the mechanisms underlying AF requires visualization of the cardiac electrical waves with high spatial and temporal resolution. While high-temporal resolution can be achieved by conventional electrical mapping traditionally used in human electrophysiological studies, the small number of intra-atrial electrodes that can be used simultaneously limits the spatial resolution and precludes any detailed tracking of the electrical waves during the arrhythmia. The introduction of optical mapping in the early 90's enabled wide-field characterization of fibrillatory activity together with sub-millimeter spatial resolution in animal models5,6 and led to the identification of rapidly spinning electrical wave patterns (rotors) as the sources of the fibrillatory activity that may occur in the ventricles or the atria.7-9 Using combined time- and frequency-domain analyses of optical mapping it is possible to demonstrate discrete sites of high frequency periodic activity during AF, along with frequency gradients between left and right atrium. The region with fastest rotors activates at the highest frequency and drives the overall arrhythmia.10,11 The waves emanating from such rotor interact with either functional or anatomic obstacles in their path, resulting in the phenomenon of fibrillatory conduction.12 Mapping the endocardial surface of the posterior left atrium (PLA) allows the tracking of AF wave dynamics in the region with the highest rotor frequency. Importantly, the PLA is the region where intracavitary catheter-based ablative procedures are most successful terminating AF in patients,13 which underscores the relevance of studying AF dynamics from the interior of the left atrium. Here we describe a sheep model of acute stretch-induced AF, which resembles some of the characteristics of human paroxysmal AF. Epicardial mapping on the left atrium is complemented with endocardial mapping of the PLA using a dual-channel rigid borescope c-mounted to a CCD camera, which represents the most direct approach to visualize the patterns of activation in the most relevant region for AF maintenance.

This report provides a detailed description of the methodology and results of simultaneous endocardial and epicardial optical mapping of electrical excitation in the intact left atrium of a Langendorff-perfused sheep heart during stretch-induced atrial fibrillation.

 Atrial fibrillation (AF) is a complex cardiac arrhythmia with high morbidity and mortality.1,2 It is the most common sustained cardiac rhythm disturbance ...

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 ...

Robotic Ablation of Atrial Fibrillation

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

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

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

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 ...

Electrophysiological Assessment of Murine Atria with High-Resolution Optical Mapping

Recent genome-wide association studies targeting atrial fibrillation (AF) have indicated a strong association between the genotype and electrophysiological phenotype in the atria. That encourages us to utilize a genetically-engineered mouse model to elucidate the mechanism of AF. However, it is difficult to evaluate the electrophysiological properties in murine atria due to their small size. This protocol describes the electrophysiological evaluation of atria using an optical mapping system with a high temporal and spatial resolution in Langendorff perfused murine hearts. The optical mapping system is assembled with dual high-speed complementary metal oxide semiconductor cameras and high magnification objective lenses, to detect the fluorescence of a voltage-sensitive dye and Ca2+ indicator. To focus on the assessment of murine atria, optical mapping is performed with an area of 2 mm &#215; 2 mm or 10 mm x 10 mm, with a 100 &#215; 100 resolution (20 &#181;m/pixel or 100 &#181;m/pixel) and sampling rate of up to 10 kHz (0.1 ms) at maximum. A 1-French size quadripolar electrode pacing catheter is placed into the right atrium through the superior vena cava avoiding any mechanical damage to the atrium, and pacing stimulation is delivered through the catheter. An electrophysiological study is performed with programmed stimulation including constant pacing, burst pacing, and up to triple extrastimuli pacing. Under a spontaneous or pacing rhythm, the optical mapping recorded the action potential duration, activation map, conduction velocity, and Ca2+ transient individually in the right and left atria. In addition, the programmed stimulation also determines the inducibility of atrial tachyarrhythmias. Precise activation mapping is performed to identify the propagation of the excitation in the atrium during an induced atrial tachyarrhythmia. Optical mapping with a specialized setting enables a thorough electrophysiological evaluation of the atrium in murine pathological models.

This protocol describes the electrophysiological evaluation of murine atria utilizing an optical mapping system with a high temporal and spatial resolution, including dual recordings of the membrane voltage and Ca2+ transient under programmed stimulation through a specialized electrode catheter.

Recent genome-wide association studies targeting atrial fibrillation (AF) have indicated a strong association between the genotype and ...

Cox-Maze IV Procedure Concomitant with Valvular Surgery In Situs Inversus Dextrocardia: A Single-Center Experience in China

Atrial fibrillation (AF) is the most common cardiac arrhythmia. The use of ablation technologies made the Cox-Maze IV procedure (CMP-IV) technically easier, faster, becoming the gold standard for the surgical treatment of AF. However, the efficacy and safety of CMP-IV in situs inversus dextrocardia are largely unknown. This paper summarizes the CMP-IV procedure performed concomitantly with valvular surgery in patients with situs inversus dextrocardia at this institution.
From February 2016 to September 2020, three dextrocardia patients with persistent AF and valvular diseases were referred to this institution for valvular and CMP-IV surgery. CMP-IV was performed using either cryoablation with a nitrous oxide (N2O)-based cryoprobe or a bipolar radiofrequency clamp and bipolar radiofrequency pen. Mechanical valve replacement or mitral vavuloplasty was performed in another patient in addition to tricuspid annuloplasty. Transmurality of the ablated atrial tissues was evaluated by electron microscopy. Heart function was assessed by transthoracic echocardiography. Cardiac rhythm was monitored by 24 h Holter at 3, 6, 12, 18, 24, and 48 months follow-up. 
All the AF was successfully eliminated in the ablation procedure without recurrence or other complications during hospitalization. The mean bypass and crossclamp times were similar in all the patients. The postoperative ventilator support time, the duration of stay in the ICU, and postoperative residence time were also not significantly different among the patients. Transmural atrial necrosis was detected in the ablated atrial tissues. Sinus rhythm maintenance was achieved at 3, 6, 12, 18, 24, and 48 months follow-up in all the patients. All valve protheses switched freely; no tricuspid regurgitation was observed. The results of the present study demonstrate that the CMP-IV is safe and effective in eliminating AF in dextrocardia patients concomitant with valvular surgery.

We summarize the Cox-Maze IV procedure concomitant with valvular surgery performed in patients with situs inversus dextrocardia at this institution.

Atrial fibrillation (AF) is the most common cardiac arrhythmia. The use of ablation technologies made the Cox-Maze IV procedure (CMP-IV) technically ...

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

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

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

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

Biology

ICE-Based 3D Remodeling for the Left Atrium and Pulmonary Vein

Three-Dimensional Modeling of the Left Atrium and Pulmonary Veins with a Precise Intracardiac Echocardiography Approach

Intracardiac echocardiography (ICE) is a novel tool for estimating cardiac anatomy during pulmonary vein isolation procedures, particularly the left atrium (LA) anatomy and pulmonary vein structures. ICE is widely used to establish a three-dimensional (3D) left atrial structural model during ablation procedures. However, it is unclear whether using ICE in a precise 3D modeling method can provide a more accurate left atrial 3D model and the transseptal approach. This study proposes a protocol to model the left atrium and pulmonary veins with ICE and fast anatomical mapping (FAM) catheter remodeling. It evaluates the accuracy of the models produced using the two methods through observer scoring. We included 50 patients who underwent ICE-based 3D remodeling and 45 who underwent FAM 3D remodeling based on pulmonary vein isolation procedures. The pulmonary vein antrum remodeling is estimated by comparing the antrum area acquired by remodeling and left atrial computed tomography angiography (CTA). The observer scores for the modeling in the ICE and FAM groups were 3.40 &#177; 0.81 and 3.02 &#177; 0.72 (P &#60; 0.05), respectively. The pulmonary vein antrum area obtained using the ICE- and FAM-based methods showed a correlation with the area acquired by left atrium CT. However, the 95% confidence interval bias was narrower in ICE-acquired models than in FAM-acquired models (-238 cm2 to 323 cm2 Vs. -363 cm2 to 386 cm2, respectively) using Bland-Altman analysis. Therefore, precise ICE possesses high accuracy in estimating the left atrial structure, becoming a promising approach for future cardiac structure estimation.

Author Spotlight: Advancements in Intracardiac Echocardiography for Atrial Anatomy Assessment 

Accurate intracardiac echocardiography (ICE) shows significant accuracy in estimating the left atrial structure, a prospective and promising cardiac structure estimation method. Here we propose a protocol for three-dimensional modeling of the left atrium and pulmonary veins with ICE and fast anatomical mapping (FAM) catheter remodeling.

Intracardiac echocardiography (ICE) is a novel tool for estimating cardiac anatomy during pulmonary vein isolation procedures, particularly the left ...