Research reported in this publication was supported in part by the National Heart, Lung, And Blood Institute of the National Institutes of Health under Award Number R44HL158375 (the content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health)

This research was reviewed and approved as exempt by the NorthShore University Health System Institutional Review Board.
1. Calculating CI for Prospective cases
<ol>
	<li>For live prospective cases, have a staff member monitor lesion placement in the control room by observing the order of lesions placed by the operator on the 3-D mapping software screen. 
	NOTE: Surpoint VISItag size may be set to a range of operator preference, for example, 2-3 mm.</li>
	<li>Have the staff member quantify the CI in real time using the below-set parameters. Amplify lesion placement seen on the screen to confirm placement using the millimeter (mm) marker setting.
	<ol>
		<li>Record a ZERO (0) increase in CI.
		<ol>
			<li>Observe that the first lesion placed on each of the right or left veins does not increase CI.</li>
			<li>Lesions that overlap the previously placed lesion (as determined by the mapping software and visual determination) do not increase CI.</li>
			<li>A lesion that is placed that connects the path of continuous lesions to other lesions (such as closing the circle around the pulmonary veins) does not increase the CI.</li>
			<li>Do not increase the CI for lesions that are placed on top of the completed continuous line of lesions for extra burning/further isolation (touch-up lesions).</li>
		</ol>
		</li>
		<li>Record a ONE (+1) increase in CI when a lesion is placed in a new location, not touching the previous lesion, for the vein on which the previous lesion was placed (this includes small gaps shown between VISItags).</li>
		<li>Record a TWO (+2) increase in CI when a new continuous set of lesions is placed in a new location, not touching any prior lesions, followed by another lesion placed to continue the previous line of lesions. Here, increase the CI by 1 for the area that is left the first time and 1 for moving away from the second area (possibly the same vein) (+1 for the initial discontinuity, +1 for the return).</li>
	</ol>
	</li>
	<li>To do a summation of CI, have the staff member record in real time the discontinuity on each of the right and left pulmonary veins throughout the case and sum the CI (per vein and total) at the end of the case.</li>
</ol>
2. Calculating CI for Retrospective cases
<ol>
	<li>To access retrospective case files, install and open 3-D mapping software.</li>
	<li>Download past cases from the 3-D mapping system.Click on System | Study Archiver | Restore. Filter cases by selecting a range of dates using the dropdown menu in the From: and To: section at the top left of the screen. 
	&#8203;EXAMPLE: From: 11 October 2018, To: 12 November 2018</li>
	<li>Type an asterisk * in either First Name, Last Name, OR Patient ID section at the top of the screen. Click on Query at the top right of the screen next to Patient ID.</li>
	<li>Select cases labeled as AF or Afib and click on the &#62; button next to the list of cases on the screen to bring each selected case to the right side of the screen.</li>
	<li>Click on Restore to restore the data and access selected cases. Click on Exit | Ok when selected cases have been fully restored (will show as 100% restored on screen).</li>
	<li>Once the selected cases have been fully restored, have the staff member begin reviewing cases for discontinuity between lesions following the steps below.
	<ol>
		<li>Click on Review Study from the main screen. A list of cases will appear on the screen. Change the order of sorting between patient name or study date to organize the review of cases by the specific patient or by the date that procedures were performed.</li>
		<li>Select the case of interest from the list of cases and click Ok. An image of all the lesions will appear on the screen as red bubbles. If lesions (VISItags) do not initially appear, then click on the VISItag toolbar to get a dropdown menu, click on the image of the VISItags from the menu, then at the bottom of the dropdown menu, select all NOT in view to make them appear on the screen as red bubbles.</li>
	</ol>
	</li>
	<li>To observe the structure of the Left Atrium with the lesions, select an LA map from the map dropdown menu at the top of the left screen that has the most VISItags appear.
	<ol>
		<li>Ensure the selected map is Active. To activate a certain map with all the VISItags, select the small circle (next to the small square) in the dropdown menu for the map that was previously selected. This will show the list of the sequential VISItags in the graph viewer section on the left side of the screen.</li>
		<li>Adjust the transparency as needed (by clicking the &#60; or &#62; buttons on the keyboard); more transparency on the map will allow the circle of lesions around the entire vein to be visible.</li>
	</ol>
	</li>
	<li>Click on Window at the very top left corner of the screen | select Graph Viewer and drag it to the left side of the screen. The Graph Viewer screen will show a list of the lesions in the order that they were placed.</li>
	<li>Click on the first point (VISItag) at the top of the list of lesions in the graph viewer section on the left side of the screen. Right-click the VISItag number, then click on Select VISItag location.
	<ol>
		<li>Observe, on the right side of the screen, the orange highlighted lesion of the left atrium. Rotate around the screen if the view is obstructed to see a clearer image of the highlighted lesion. Do this by holding down the center button on the mouse and dragging the mouse on the table surface.</li>
		<li>Repeat steps 2.9.-2.9.1. for every VISItag in sequential order on the graph view list of lesions.</li>
	</ol>
	</li>
	<li>As the staff member highlights each VISItag lesion, ask them to begin recording the CI for the right and left pulmonary veins using the parameters defined below.
	<ol>
		<li>Record a ZERO (0) increase in CI:
		<ol>
			<li>The first lesion placed on each of the right or left vein does not increase CI.</li>
			<li>Lesions that overlap the previously placed lesion (as determined by the 3-D mapping software and visual determination) do not increase CI.</li>
			<li>A lesion that is placed that connects the path of continuous lesions to other lesions (such as closing the circle around the pulmonary veins) does not increase the CI.</li>
			<li>Do not increase the CI for lesions that are placed on top of the completed continuous line of lesions for extra burning/further isolation (touch-ups).</li>
		</ol>
		</li>
		<li>Record a ONE (+1) increase in CI:
		<ol>
			<li>Add one (+1) discontinuity for any lesion placement that is clearly not touching the last lesion placed.</li>
			<li>Add one (+1) discontinuity for every significant jump across each pulmonary vein (except in scenario 2.10.1.1-do not add discontinuity increment for the first lesion on a new vein after the first vein is isolated).</li>
			<li>Sum the CI once every VISItag has been selected and observed. The summation will be the total CI score. Score CI separately for both left and right pulmonary veins for more granular data. The sum of the two scores equals the total continuity index score.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>To complete data collection of additional relevant case information (i.e., ablating physician, date of procedure, patient gender, DOB), follow the steps below.
	<ol>
		<li>After selecting each tag, select study from far to lefthand corner, then click on continue study.</li>
		<li>Click on Setup | study and record the additional data of interest.</li>
	</ol>
	</li>
	<li>To exit the software, click on Study in the top left corner of the screen, then select Exit.</li>
</ol>

Assessing Continuity Index in Pulmonary Vein Isolation with Esophageal Cooling 

<ol>
	<li>Scott, M., 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=Contemporary+trends+in+cardiac+electrophysiology+procedures+in+the+United+States,+and+impact+of+a+global+pandemic.">Contemporary trends in cardiac electrophysiology procedures in the United States, and impact of a global pandemic.</a> Heart Rhythm O2. 4 (3), 193-199 (2023).</li><li>Jankelson, L., 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=Lesion+sequence+and+catheter+spatial+stability+affect+lesion+quality+markers+in+atrial+fibrillation+ablation.">Lesion sequence and catheter spatial stability affect lesion quality markers in atrial fibrillation ablation.</a> JACC Clin Electrophysiol. 7 (3), 367-377 (2021).</li><li>Kautzner, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EFFICAS+II:+optimization+of+catheter+contact+force+improves+outcome+of+pulmonary+vein+isolation+for+paroxysmal+atrial+fibrillation.">EFFICAS II: optimization of catheter contact force improves outcome of pulmonary vein isolation for paroxysmal atrial fibrillation.</a> Europace. 17 (8), 1229-1235 (2015).</li><li>Thomas, 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=Higher+contact+force+during+radiofrequency+ablation+leads+to+a+much+larger+increase+in+edema+as+compared+to+chronic+lesion+size.">Higher contact force during radiofrequency ablation leads to a much larger increase in edema as compared to chronic lesion size.</a> J Cardiovasc Electrophysiol. 29 (8), 1143-1149 (2018).</li><li>Ren, J. F., Callans, D. J., Schwartzman, D., Michele, J. J., Marchlinski, F. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+in+local+wall+thickness+correlate+with+pathologic+lesion+size+following+radiofrequency+catheter+ablation:+an+intracardiac+echocardiographic+imaging+study.">Changes in local wall thickness correlate with pathologic lesion size following radiofrequency catheter ablation: an intracardiac echocardiographic imaging study.</a> Echocardiography. 18 (6), 503-507 (2001).</li><li>Della Rocca, 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=Clinical+presentation,+diagnosis,+and+treatment+of+atrioesophageal+fistula+resulting+from+atrial+fibrillation+ablation.">Clinical presentation, diagnosis, and treatment of atrioesophageal fistula resulting from atrial fibrillation ablation.</a> J Cardiovasc Electrophysiol. 32 (9), 2441-2450 (2021).</li><li>Shen, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Commentary:+The+rising+storm+of+atrioesophageal+fistulae+after+catheter+ablation+for+atrial+fibrillation.">Commentary: The rising storm of atrioesophageal fistulae after catheter ablation for atrial fibrillation.</a> JTCVS Tech. 6, 169 (2021).</li><li>Tan, M. 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=Causes+of+early+mortality+after+catheter+ablation+of+atrial+fibrillation.">Causes of early mortality after catheter ablation of atrial fibrillation.</a> Circ Arrhythm Electrophysiol. 16 (5), e011365 (2023).</li><li>Sanchez, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atrioesophageal+fistula+rates+before+and+after+adoption+of+active+esophageal+cooling+during+atrial+fibrillation+ablation.">Atrioesophageal fistula rates before and after adoption of active esophageal cooling during atrial fibrillation ablation.</a> JACC Clin Electrophysiol. 9 (12), 2558-2570 (2023).</li><li>Wm Leung, L., 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=Effect+of+esophageal+cooling+on+ablation+lesion+formation+in+the+left+atrium:+insights+from+ablation+index+data+in+the+IMPACT+trial+and+clinical+outcomes.">Effect of esophageal cooling on ablation lesion formation in the left atrium: insights from ablation index data in the IMPACT trial and clinical outcomes.</a> J Cardiovasc Electrophysiol. 33 (12), 2546-2557 (2022).</li><li>Joseph, 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=Improved+1-year+outcomes+after+active+cooling+during+left+atrial+radiofrequency+ablation.">Improved 1-year outcomes after active cooling during left atrial radiofrequency ablation.</a> J Interv Card Electrophysiol. 66 (7), 1621-1629 (2023).</li><li>Mercado Montoya, M., 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=Proactive+esophageal+cooling+protects+against+thermal+insults+during+high-power+short-duration+radiofrequency+cardiac+ablation.">Proactive esophageal cooling protects against thermal insults during high-power short-duration radiofrequency cardiac ablation.</a> International Journal of Hyperthermia. 39 (1), 1202-1212 (2022).</li><li>Sessler, D. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temperature+monitoring+and+perioperative+thermoregulation.">Temperature monitoring and perioperative thermoregulation.</a> Anesthesiology. 109 (2), 318-338 (2008).</li><li>Griffin, B. R., Frear, C. C., Babl, F., Oakley, E., Kimble, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cool+running+water+first+aid+decreases+skin+grafting+requirements+in+pediatric+burns:+a+cohort+study+of+two+thousand+four+hundred+ninety-five+children.">Cool running water first aid decreases skin grafting requirements in pediatric burns: a cohort study of two thousand four hundred ninety-five children.</a> Ann Emerg Med. 75 (1), 75-85 (2020).</li><li>Bender, 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=The+acute+impact+of+local+cooling+versus+local+heating+on+human+skin+microcirculation+using+laser+Doppler+flowmetry+and+tissue+spectrophotometry.">The acute impact of local cooling versus local heating on human skin microcirculation using laser Doppler flowmetry and tissue spectrophotometry.</a> Burns. 46 (1), 104-109 (2019).</li><li>Cooper, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Active+esophageal+cooling+during+radiofrequency+ablation+of+the+left+atrium:+data+review+and+update.">Active esophageal cooling during radiofrequency ablation of the left atrium: data review and update.</a> Expert Rev Med Devices. 19 (12), 949-957 (2022).</li><li>Joseph, 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=Reduced+procedure+time+and+variability+with+active+esophageal+cooling+during+radiofrequency+ablation+for+atrial+fibrillation.">Reduced procedure time and variability with active esophageal cooling during radiofrequency ablation for atrial fibrillation.</a> JoVE. (186), (2022).</li><li>Bunch, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hope,+hype,+and+reality+of+pulsed+field+ablation+for+atrial+fibrillation.">Hope, hype, and reality of pulsed field ablation for atrial fibrillation.</a> N Engl J Med. 389 (18), 1720-1721 (2023).</li></ol>

Catherine Lazarus, Jacob Sherman, Natalie Putzel,&#160;and William Zagrodzky have interned with Attune Medical; Tiffany Sharkoski has employment at Attune Medical; Erik Kulstad has equity and employment in Attune Medical; Mark Metzl has consulted for Abbott, Biosense Webster, Attune Medical, Medtronic, Sanofi Aventis, and Philips. All remaining authors have nothing to disclose.

The CI is an additional measure that reflects the quality of isolation obtained in PVI cases. Kautzner et al., in the EFFICAS II study, developed the initial method for measuring this key variable and demonstrated the significant influence of CI on the completeness of isolation and the resultant freedom from arrhythmia3. In the protocol described here, the CI calculation was modified from the EFFICAS II study to further simplify the calculation and to provide a simpler means to calculate CI both prospectively in real-time live cases, as well as retrospectively from routinely obtained case recordings (Figure 4). Viewing the pulmonary veins and assessing which quadrant any given lesion was placed in during a live case can be challenging (due to the lack of formal demarcations of pulmonary vein segments and the resulting ambiguity of an appropriate number of index units to increment). The proposed modified method described here captures the underlying presumptions and methodology reported in EFFICAS II while offering a more feasible approach to obtaining the CI for each case that may in turn lend itself to automation in existing mapping systems.
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/66688/66688fig04.jpg" /> 
Figure 4: Example of modified continuity index calculation for real-time and retrospective calculation. These calculations involve incrementing each non-adjacent lesion by one unit only. Abbreviation: CI= continuity index. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66688/66688fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The critical piece to determining the CI in prospective cases is having a staff member available with the ability to follow lesion placement and record data during real-time procedures. The critical piece for retrospective case review is having a staff member with access to the CARTO 3 mapping software to be able to easily and efficiently access the case and record the data. The critical step of the protocol that details counting and summation of the CI (steps 2.9.7-2.10) for retrospective cases typically takes ~10-15 min. However, approximately 30 additional min are required to complete the prior steps, as downloading can take over 10 min per case.
Limitations in the method include the fact that calculating the CI during a live case requires an additional person to be in the room while a physician is ablating, and the time requirement for this effort. This individual typically spends an hour or longer in each case to ensure they are present from first through last lesion placement. Many labs and control rooms have limited space, and an additional person may be difficult to accommodate. Measuring the CI for a retrospective case also requires a dedicated person to be available. In this study, one representative retrospective case was provided as a comparison of CI in a LET-monitored PVI. Additional data are currently in collection to provide a more formal and adequately powered comparative analysis.
Additional limitations include that the data collected were from 4 operators at a single center for both the prospective and retrospective cases. While retrospective review likely minimized bias, it is possible that the electrophysiologist may have altered their lesion placement strategy to minimize CI while data were being obtained during the prospective cases. Additionally, the CI of each case was determined by one reviewer and not independently validated by a second reviewer.
Future applications or directions of the method would be automating the CI acquisition process. Similar to catheter-tissue contact force, CI would ideally be an auto-generated value calculated in real-time during the case, measured by lesion location placement via the catheter and the existing electroanatomical mapping capabilities. Physicians approaching 5-6 CI units during a case could then adjust their next planned lesion placement or adopt other methods to minimize lesion discontinuity/high CIs.
Proactive esophageal cooling utilizing the ensoETM (Attune Medical, Chicago) during RF ablation allows the attainment of a low CI. Previous publications suggest this may be a possible mechanism for the higher rates of long-term freedom from arrhythmia seen in PVI cases with proactive cooling10,11. A prospective randomized controlled trial (NCT04577859) comparing the effect of proactive esophageal cooling versus LET monitoring on long-term procedure efficacy is underway. This multi-center study has an enrollment target of 250 patients, and sites will include CI data. Further exploration of this variable within a randomized controlled trial is expected to provide stronger estimates of the influence of CI on long-term freedom from arrhythmia. Strong evidence of a significant influence may in turn support efforts from ablation catheter manufacturers to develop software to include this measure.

Pulmonary vein isolation (PVI) using radiofrequency (RF) catheter ablation has become one of the most common methods for restoring sinus rhythm in the rising number of atrial fibrillation (AF) cases worldwide1. Research has shown that indirect lesion quality markers, such as impedance decline, catheter-tissue contact force, catheter stability, and bipolar electrogram amplitude reduction serve as evidence of transmurality, which contributes to the effectiveness of PVI2. Despite these available markers, improving on successful isolation and ultimately, long-term freedom from arrhythmias remains a high priority for electrophysiologists. Clinical data have shown that the placement of adjacent, overlapping, and continuous lesions along the circumferential isolation line is associated with lower recurrence rates and a higher likelihood of achieving transmurality-associated unipolar electrogram (TUE)2,3.
Kautzner et al., in the EFFICAS II Study, developed the Continuity Index (CI) to quantify discontinuous lesion placement in efforts to further understand how the order of lesion placement during an ablation impacts both short and long-term efficacy (Figure 1)3. The CI refers to the number of positions the catheter tip has moved over to place subsequent lesions in non-adjacent positions after stopping RF power early due to local overheating. A higher CI implies more discontinuity in sequential lesion placement. This study suggested that a PVI with a low CI (CI &#60; 6) resulted in a significant increase in successful isolation as a result of contiguous catheter movement allowing more effective electrical isolation compared to a CI &#8805; 63. One possible mechanism for the observed decrease in long-term efficacy associated with a higher CI is the rapid edema formation that occurs around lesions, which has been thought to result in reversible PVI4,5. When subsequent lesions are delayed, rapid edema formation may prevent transmural or contiguous lesion formation at adjacent positions and may significantly alter or conceal local electrograms in the region of stunned tissue2,3. There exists a need to prevent esophageal thermal injury and potentially lethal atrioesophageal fistula (AEF) during PVI; however, the use of traditional luminal esophageal temperature (LET) monitoring often forces cessation of RF energy application as a result of local overheating detected in the esophagus6,7,8. This in turn causes the CI to increase significantly.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/66688/66688fig01.jpg" /> 
Figure 1: Example of continuity index calculation as originally defined for two examples of ablation patterns3.&#160;This figure was taken from Kautzner et al.3. Abbreviation: CI = continuity index. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66688/66688fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
A proactive esophageal cooling device (see the Table of Materials) has been granted marketing authorization by the Food and Drug Administration (FDA) to reduce the likelihood of ablation-related esophageal injury resulting from radiofrequency cardiac ablation procedures, and data from over 25,000 patients suggest a significant reduction in AEF rate with cooling9. Long-term follow-up data also suggest improved freedom from arrhythmia when using cooling as opposed to LET monitoring10,11. The cooling device is a non-sterile, multi-lumen silicone tube placed in the esophagus, much like an orogastric tube, for the purpose of cooling or warming a patient. The tube acts as a heat sink for RF energy inadvertently delivered to the esophagus, thus minimizing esophageal tissue damage, while pericardial tissues prevent significant cooling of atrial tissue12. Device temperature is controlled by connecting the esophageal cooling device to an external heat exchanger that circulates distilled water within the device (Figure 2). The device can be placed by any provider cleared to place a standard orogastric tube (nurses, physicians, paramedics). For ablation procedures, the device is usually placed by the anesthesiologist or CRNA immediately following induction of anesthesia and intubation. Placement is confirmed by visualizing the radiopaque distal tip in the gastric space on fluoroscopy. The device can also be seen on intracardiac echocardiography (ICE) commonly used during ablations. During the procedure, the patient&#39;s temperature can be continuously measured by usual means (Foley, rectal, forehead, axillary, or tympanic membrane temperature probe), but not via esophageal probe.&#160;Recall that axillary temperature is typically 1.5&#176; C lower than core temperature, and adding this to the axillary measurement is necessary to reflect patient core temperature13.
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/66688/66688fig02.jpg" /> 
Figure 2: Diagram of the active esophageal temperature management system. The commercially available heat exchange unit generates temperature-controlled water, which is then delivered across standard tubing sets into the device placed in the esophagus. After circulating at a rate of ~1.5 L/min inside the device, the water returns to the heat exchange unit. The independent central lumen allows gastric decompression and suction. The radiopacity of the distal tip of the device allows for fluoroscopic visualization in the gastric space to confirm correct placement. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66688/66688fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Recent burn injury literature has found a strong association between cooling after thermal injury and a reduction in burn injury severity, with the mechanisms of this effect extending beyond dissipation of heat, to include the alteration of cellular behavior through (i) decreasing release of lactate and histamine, (ii) stabilizing thromboxane and prostaglandin levels, (iii) slowing local metabolism, (iv) altering membrane permeability, and (iv) inhibiting kallikrein activity14. The growing understanding of the local effects of hypothermia in burn injury provides a mechanistic underpinning for the significant safety benefit seen with the esophageal cooling device utilized in this study15. Proactive esophageal cooling allows for the contiguous placement of the sequential lesions without interruption and without the need to pause for local overheating conditions or temperature alarms, likely due to the mechanisms described above. This in turn decreases operator cognitive load, reduces procedure time, and allows a reduced CI which can increase long-term PVI success16,17.
Our aim in this protocol is to describe the methods of prospectively calculating a modified CI in real-time cases and describe the methods used to calculate a modified CI retrospectively in recorded cases. We then provide representative results for cases that utilized both real-time observations utilizing proactive esophageal cooling as well as retrospective data prior to the adoption of cooling. An advantage of this approach is that the CI can be measured easily both in real-time as well as retrospectively. By observing the CI in PVI cases with and without cooling, the impact of cooling on long-term efficacy and lesion continuity can be further quantified, and the use of the CI as a PVI quality measure can potentially be further promoted. Continuing research to explore CI and lesion quality in terms of RF ablation and clinical efficacy remains important, especially when pulsed field ablation appears to be associated with the risk of new adverse events without convincingly improving long-term outcomes 18.

<table><tbody><tr><td>Blanketrol III hyper-hypothermia system</td><td>Gentherm Medical, Cincinnati, OH</td><td>Model 233</td><td>Programmable heat exchanger for temperature regulation</td></tr><tr><td>Carto&amp;nbsp;3 System</td><td>Biosense Webster, Inc. (J&amp;amp;J MedTech), Irvine, CA</td><td>FG-5400-00</td><td>3-D mapping system with the integration, scalability and insights to help electrophysiologists make optimal treatment decisions.</td></tr><tr><td>ensoETM</td><td>Attune Medical, Chicago, IL</td><td>ECD02A</td><td>Active esophageal cooling device</td></tr><tr><td>Esophageal Stethoscope with Temperature Sensor Level 1</td><td>Smiths Medical ASD Inc., Minneapolis, MN</td><td>ES400-18</td><td>Luminal Esophageal Temperature (LET) monitoring system</td></tr></tbody></table>

determination of continuity index values in atrial fibrillation ablation with proactive esophageal cooling

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

Data from a total of 75 patients treated with PVI using proactive esophageal cooling were recorded. The mean patient age was 69.8 &#177; 9.0 years, with 42.7% female, 37.3% paroxysmal, and 62.7% persistent AF. The mean &#177; SD CI for PVI was 2.6 &#177; 3.7 and was similar between the isolation of the left pulmonary veins (1.2 &#177; 1.7) and the right pulmonary veins (1.4 &#177; 2.3). Out of the 75 patients, only 5.3% (4) had a CI above 6 on either side, and only 22% (16) had a total CI above 6. Figure 3 shows the mean CI for left and right veins for the cohort. As a comparison, a representative case from the same lab using LET monitoring was reviewed, and found that the total CI was 29; 15 on the left side and 14 on the right side.
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/66688/66688fig03.jpg" /> 
Figure 3: Mean CI of left and right pulmonary veins for a cohort of 75 patients analyzed using proactive esophageal cooling. Abbreviation: CI = continuity index. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66688/66688fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Read this Scientific Article Protocol about Author Spotlight: Improving Lesion Contiguity in Pulmonary Vein Isolation via Proactive Esophageal Cooling at JoVE.com

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

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

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

Radiofrequency (RF) ablation to perform pulmonary vein isolation (PVI) for the treatment of atrial fibrillation involves some risk to collateral ...

determination-continuity-index-values-atrial-fibrillation-ablation

Nanyang Technological University

Research

JoVE Journal

Medicine

928 Views.  Northwestern University. Dit protocol beschrijft de methoden die worden gebruikt om de continuïteitsindex te bepalen bij patiënten die isolatieprocedures voor de longader ondergaan met behulp van radiofrequente ablatie, en toont de verschillen in continuïteitsindex tussen ablatieprocedures met behulp van proactieve slokdarmkoeling, in vergelijking met procedures met behulp van luminale slokdarmtemperatuurbewaking. Proactieve slokdarmkoeling met behulp van een speciaal apparaat heeft een vergunning gekregen van de ...

Video: Auteur in de schijnwerpers: verbetering van de aaneensluiting van laesies in isolatie van de longader via proactieve slokdarmkoeling

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 ...

The WATCHMAN Left Atrial Appendage Closure Device for Atrial Fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia, affecting an estimated 6 million people in the United States 1. Since AF affects primarily elderly people, its prevalence increases parallel with age. As such, it is expected that 15.9 million Americans will be affected by the year 2050 2. Ischemic stroke occurs in 5% of non-anticoagulated AF patients each year. Current treatments for AF include rate control, rhythm control and prevention of stroke 3.
The American College of Cardiology, American Heart Association, and European Society of Cardiology currently recommended rate control as the first course of therapy for AF 3. Rate control is achieved by administration of pharmacological agents, such as &beta;-blockers, that lower the heart rate until it reaches a less symptomatic state 3. Rhythm control aims to return the heart to its normal sinus rhythm and is typically achieved through administration of antiarrhythmic drugs such as amiodarone, electrical cardioversion or ablation therapy. Rhythm control methods, however, have not been demonstrated to be superior to rate-control methods 4-6. In fact, certain antiarrhythmic drugs have been shown to be associated with higher hospitalization rates, serious adverse effects 3, or even increases in mortality in patients with structural heart defects 7. Thus, treatment with antiarrhythmics is more often used when rate-control drugs are ineffective or contraindicated. Rate-control and antiarrhythmic agents relieve the symptoms of AF, including palpitations, shortness of breath, and fatigue 8, but don't reliably prevent thromboembolic events 6.
Treatment with the anticoagulant drug warfarin significantly reduces the rate of stroke or embolism 9,10. However, because of problems associated with its use, fewer than 50% of patients are treated with it. The therapeutic dose is affected by drug, dietary, and metabolic interactions, and thus requires detailed monitoring. In addition, warfarin has the potential to cause severe, sometimes lethal, bleeding 2. As an alternative, aspirin is commonly prescribed. While aspirin is typically well tolerated, it is far less effective at preventing stroke 10. Other alternatives to warfarin, such as dabigatran 11 or rivaroxaban 12 demonstrate non-inferiority to warfarin with respect to thromboembolic events (in fact, dabigatran given as a high dose of 150 mg twice a day has shown superiority). While these drugs have the advantage of eliminating dietary concerns and eliminating the need for regular blood monitoring, major bleeding and associated complications, while somewhat less so than with warfarin, remain an issue 13-15.
Since 90% of AF-associated strokes result from emboli that arise from the left atrial appendage (LAA) 2, one alternative approach to warfarin therapy has been to exclude the LAA using an implanted device to trap blood clots before they exit. Here, we demonstrate a procedure for implanting the WATCHMAN Left Atrial Appendage Closure Device. A transseptal cannula is inserted through the femoral vein, and under fluoroscopic guidance, inter-atrial septum is crossed. Once access to the left atrium has been achieved, a guidewire is placed in the upper pulmonary vein and the WATCHMAN Access Sheath and dilator are advanced over the wire into the left atrium. The guidewire is removed, and the access sheath is carefully advanced into the distal portion of the LAA over a pigtail catheter. The WATCHMAN Delivery System is prepped, inserted into the access sheath, and slowly advanced. The WATCHMAN device is then deployed into the LAA. The device release criteria are confirmed via fluoroscopy and transesophageal echocardiography (TEE) and the device is released.

The accompanying video describes a procedure for percutaneous placement of the WATCHMAN Left Atrial Appendage (LAA) Device. The WATCHMAN is a nitinol device designed to be permanently implanted at, or slightly distal to, the opening of the left atrial appendage (LAA) to trap blood clots before they exit the LAA, preventing thromboembolic stroke.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, affecting an estimated 6 million people in the United States 1. Since AF affects primarily ...

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

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

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

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

Direct Pressure Monitoring Accurately Predicts Pulmonary Vein Occlusion During Cryoballoon Ablation

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

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

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

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 ...

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

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

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

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

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

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

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

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

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

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

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

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

Biology

Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System

Rapid, safe, and effective cardiac mapping is critical for the management of complex arrhythmias, yet current methods face significant limitations. The 12-lead electrocardiogram (ECG), while essential for initial diagnosis, lacks the spatial resolution and depth needed to guide advanced procedures such as catheter ablation or cardiac resynchronization therapy device implantation. On the other hand, invasive mapping techniques provide detailed electrical activity but require multiple catheter placements, increasing procedural risks and complexity. These methods are time-consuming, expensive, and offer limited real-time assessment, especially in dynamic arrhythmias like atrial fibrillation (AF), unstable arrhythmia, and cardiac resynchronization therapy (CRT).
This study introduces a noninvasive, imageless electrocardiographic imaging (Imageless-ECGI) system designed to complement traditional methods by providing real-time, beat-to-beat cardiac maps. Without the need for pre-procedural imaging, this system captures high-resolution electrical activity across the entire heart, offering a safer and more efficient alternative to invasive mapping. By combining the immediacy of surface recordings with the spatial accuracy of modern computational models, the Imageless-ECGI system bridges the gap between traditional ECG and invasive mapping, potentially transforming the workflow in electrophysiology labs.

This study introduces a novel approach for real-time cardiac mapping using a noninvasive, imageless electrocardiographic imaging system. This system enables the acquisition of electrophysiological cardiac maps without requiring pre-procedural computed tomography or magnetic resonance imaging scans, enabling efficient guidance for cardiac procedures such as ablation and cardiac resynchronization therapy implants.

Rapid, safe, and effective cardiac mapping is critical for the management of complex arrhythmias, yet current methods face significant limitations. The ...

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

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