The authors would like to acknowledge the staff of the UT Southwestern Department of Electrophysiology: Cheryl Thomas RN, Roma Alfonso RN, Eileen Dwyer RN, Anish Varghese RN, Josey George RCIS, Pam Harrison RCIS, and Carolyn Carlson RN. Data are available upon request from the authors.

This research was performed in compliance with the institutional guidelines of the University of Texas, Southwestern Medical Center, approval number STU-2021-1166. Data were collected retrospectively through chart review, and thus the need for patient consent was waived.
1. User workflow analysis
<ol>
	<li>During the user workflow analysis, use contextual inquiry to identify the key procedural steps and identify the personnel responsible for documenting these steps. Identify the EHR data structures that represent them, and map these data structures to tables in the EHR&#39;s reporting database. 
	&#8203;NOTE: Contextual inquiry is a method combining real-time field observations with the interactive probing of workers during work activities14,15.</li>
	<li>Identification of key procedural events and the personnel responsible for documentation
	<ol>
		<li>Observe and interview faculty and trainee physicians, circulating and scrub staff, anesthesiology staff, and device representatives to develop a process map of the key procedural events required for tracking performance.</li>
		<li>Note the following key procedural events: patient arrival time, the time out procedure, vascular access attainment, sheath insertion and removal, esophageal cooling device or temperature probe insertion and removal, vascular closure, patient emergence, and patient departure time.</li>
	</ol>
	</li>
</ol>
2. Observation of placement and use of an esophageal cooling device
NOTE: The placement and use of the active esophageal cooling device have been previously demonstrated and can be seen in Zagrodzky et al.10.
<ol>
	<li>In brief, first connect the esophageal cooling device to the external heat exchanger. Turn on the power and activate the water flow to provide adequate device stiffness and ensure the absence of any leaks. Apply a generous amount of lubrication to the distal 15 cm and place the device in a similar fashion to a standard orogastric tube.</li>
	<li>Determine proper esophageal cooling device placement using standard fluoroscopy demonstrating the device tip below the patient&#39;s diaphragm; if zero-fluoroscopy techniques are used, visualize the device on intracardiac echocardiography.&#160;
	<ol>
		<li>If using fluoroscopy, use standard settings as chosen by the lab with an anterior-posterior view, and center the image at the patient&#39;s xiphoid.</li>
		<li>If using intracardiac echocardiography, rotate&#160;the catheter to obtain a posterior view to allow&#160;for visualization of the device in the esophagus, posterior to the left atrium.&#160;</li>
	</ol>
	</li>
</ol>
3. Structured data extraction
<ol>
	<li>Identification of the data elements representing procedural events: after identification of the users responsible for procedural documentation (i.e., circulating or documenting nurse), which may be facility-specific, identify and record the documentation workflows and data elements representing the procedural activities described in step 1.2. Data elements in this step include correlating the sheath insertion to the EHR flowsheet elements representing this data point.</li>
	<li>Map and extract the data elements to database structures for bulk reporting: after identification of the data structures representing the key procedural steps, use EHR database mapping tools to translate these structures from the operational data structures to relational database tables in the reporting database. Extract the data into a tabular format for integration with the results of the manual chart review.</li>
</ol>
4. Identification of data necessitating manual extraction
<ol>
	<li>Identify any necessary data that cannot be easily extracted via database structures.</li>
	<li>For this protocol, perform manual extraction for the following data elements: energy used in ablation; esophageal protection method used, type of atrial fibrillation, episode of postoperative pain during admission, episode of postoperative pain following discharge (within 30 days).</li>
</ol>
5. Manual data extraction
<ol>
	<li>Create a REDCap database instrument to facilitate manual chart review16,17. The extracted data are shown in Supplementary File 1 (REDCap data storage extraction form).
	<ol>
		<li>Create a new project within REDCap by clicking the New Project button. After naming the project, this will lead to a page titled: Project Setup. Navigate to the second section titled: Design your data collection instruments and click the Online Designer button.</li>
		<li>In the online designer, click Create a new instrument from scratch. In the instrument, add all the fields listed in step 4.2, in addition to a patient medical record number in order to correlate the manual data collected, to the data that was collected via EHR database structure extraction.</li>
		<li>Once the instrument is finalized, click the Move project to production button. From the left panel, click Add / Edit Records to view the finalized data instruments for inputting the data during the chart review.</li>
	</ol>
	</li>
	<li>Identify patients that fit within the study inclusion criteria, in this case, all patients that received ablations for AF between January 2020 and January 2022.</li>
	<li>Perform a manual chart review of the included patients, adding the data collected into the project created in REDCap for future analysis.</li>
</ol>

<ol>
	<li>McCarthy, P. 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=Surgery+and+catheter+ablation+for+atrial+fibrillation:+History,+current+practice,+and+future+directions.">Surgery and catheter ablation for atrial fibrillation: History, current practice, and future directions.</a> Journal of Clinical Medicine. 11 (1), 210 (2021).</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> Journal of Cardiovascular Electrophysiology. 32 (9), 2441-2450 (2021).</li><li>Leung, L. W. 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=Preventing+esophageal+complications+from+atrial+fibrillation+ablation:+A+review.">Preventing esophageal complications from atrial fibrillation ablation: A review.</a> Heart Rhythm O2. 2, 651-664 (2021).</li><li>Schoene, K., 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=Oesophageal+Probe+Evaluation+in+Radiofrequency+Ablation+of+Atrial+Fibrillation+(OPERA):+Results+from+a+prospective+randomized+trial.">Oesophageal Probe Evaluation in Radiofrequency Ablation of Atrial Fibrillation (OPERA): Results from a prospective randomized trial.</a> Europace. 22 (10), 1487-1494 (2020).</li><li>Chen, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Catheter+ablation+of+atrial+fibrillation+using+ablation+index-guided+high+power+(50+W)+for+pulmonary+vein+isolation+with+or+without+esophageal+temperature+probe+(the+AI-HP+ESO+II).">Catheter ablation of atrial fibrillation using ablation index-guided high power (50 W) for pulmonary vein isolation with or without esophageal temperature probe (the AI-HP ESO II).</a> Heart Rhythm. 17 (11), 1833-1840 (2020).</li><li>Meininghaus, 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=Temperature+monitoring+and+temperature-driven+irrigated+radiofrequency+energy+titration+do+not+prevent+thermally-induced+esophageal+lesions+in+pulmonary+vein+isolation:+A+randomized+study+controlled+by+esophagoscopy+before+and+after+catheter+ablation.">Temperature monitoring and temperature-driven irrigated radiofrequency energy titration do not prevent thermally-induced esophageal lesions in pulmonary vein isolation: A randomized study controlled by esophagoscopy before and after catheter ablation.</a> Heart Rhythm. 18 (6), 926-934 (2021).</li><li>Barbhaiya, C. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Esophageal+temperature+dynamics+during+high-power+short-duration+posterior+wall+ablation.">Esophageal temperature dynamics during high-power short-duration posterior wall ablation.</a> Heart Rhythm. 17 (5), 721-727 (2020).</li><li>Kar, R., Post, A., John, M., Rook, A., Razavi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+initial+ex+vivo+evaluation+of+temperature+profile+and+thermal+injury+formation+on+the+epiesophageal+surface+during+radiofrequency+ablation.">An initial ex vivo evaluation of temperature profile and thermal injury formation on the epiesophageal surface during radiofrequency ablation.</a> Journal of Cardiovascular Electrophysiology. 32 (3), 704-712 (2021).</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=Procedural+time+reduction+associated+with+active+esophageal+cooling+during+pulmonary+vein+isolation.">Procedural time reduction associated with active esophageal cooling during pulmonary vein isolation.</a> Journal of Interventional Cardiac Electrophysiology. , (2022).</li><li>Zagrodzky, 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=Cooling+or+warming+the+esophagus+to+reduce+esophageal+injury+during+left+atrial+ablation+in+the+treatment+of+atrial+fibrillation.">Cooling or warming the esophagus to reduce esophageal injury during left atrial ablation in the treatment of atrial fibrillation.</a> Journal of Visualized Experiments. (157), e60733 (2020).</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=Arrhythmia+recurrence+reduction+with+an+active+esophageal+cooling+device+during+radiofrequency+ablation.">Arrhythmia recurrence reduction with an active esophageal cooling device during radiofrequency ablation.</a> EP Europace. 24, (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=Reduction+of+procedure+time+with+active+esophageal+cooling+during+left+atrial+ablation+in+zero-fluoroscopy+cases.">Reduction of procedure time with active esophageal cooling during left atrial ablation in zero-fluoroscopy cases.</a> Journal of the American College of Cardiology. 79, 161 (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=One-year+outcomes+after+active+cooling+during+left+atrial+radiofrequency+ablation.">One-year outcomes after active cooling during left atrial radiofrequency ablation.</a> Journal of the American College of Cardiology. 79, 114 (2022).</li><li>Holtzblatt, K., Wendell, J. B., Wood, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Rapid Contextual Design: A How-to Guide to Key Techniques for User-Centered Design. , (2005).</li><li>Karen, H., Sandra, J., Schuler, D., Namioka, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contextual+inquiry:+A+participatory+technique+for+system+design.">Contextual inquiry: A participatory technique for system design.</a> Participatory Design. , 177-210 (2017).</li><li>Harris, P. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+REDCap+consortium:+Building+an+international+community+of+software+platform+partners.">The REDCap consortium: Building an international community of software platform partners.</a> Journal of Biomedical Informatics. 95, 103208 (2019).</li><li>Harris, P. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Research+electronic+data+capture+(REDCap)-A+metadata-driven+methodology+and+workflow+process+for+providing+translational+research+informatics+support.">Research electronic data capture (REDCap)-A metadata-driven methodology and workflow process for providing translational research informatics support.</a> Journal of Biomedical Informatics. 42 (2), 377-381 (2009).</li><li>Cheng, H., 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=Prolonged+operative+duration+is+associated+with+complications:+A+systematic+review+and+meta-analysis.">Prolonged operative duration is associated with complications: A systematic review and meta-analysis.</a> Journal of Surgical Research. 229, 134-144 (2018).</li><li>Medi, 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=Subtle+post-procedural+cognitive+dysfunction+after+atrial+fibrillation+ablation.">Subtle post-procedural cognitive dysfunction after atrial fibrillation ablation.</a> Journal of the American College of Cardiology. 62 (6), 531-539 (2013).</li><li>Mercado, M., Leung, L., Gallagher, M., Shah, S., Kulstad, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+esophageal+protection+from+radiofrequency+ablation+via+a+cooling+device:+An+analysis+of+the+effects+of+ablation+power+and+heart+wall+dimensions.">Modeling esophageal protection from radiofrequency ablation via a cooling device: An analysis of the effects of ablation power and heart wall dimensions.</a> Biomedical Engineering Online. 19 (1), 77 (2020).</li><li>Zagrodzky, J., Bailey, S., Shah, S., Kulstad, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+active+esophageal+cooling+on+fluoroscopy+usage+during+left+atrial+ablation.">Impact of active esophageal cooling on fluoroscopy usage during left atrial ablation.</a> The Journal of Innovations in Cardiac Rhythm Management. 12 (11), 4749-4755 (2021).</li><li>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=Oesophageal+thermal+protection+during+AF+ablation:+Effect+on+left+atrial+myocardial+ablation+lesion+formation+and+patient+outcomes.">Oesophageal thermal protection during AF ablation: Effect on left atrial myocardial ablation lesion formation and patient outcomes.</a> EP Europace. 23, (2021).</li></ol>

CJ reports an internship with Attune Medical; JC reports funding for data collection in this study from Attune Medical; EK reports employment and equity in Attune Medical. The rest of the authors have no conflicts of interest and no financial interests to disclose.

This investigation demonstrates the use of advanced informatics techniques, including contextual inquiry, workflow analysis, and the pairing of key activities with electronic health record (EHR) data structures, to analyze the impact on procedural times of two different esophageal protection methods utilized during cardiac ablation. This is the first study of the effects of esophageal cooling on procedure time and variability to be performed in an academic medical center, where trainees (fellows) receive clinical training in electrophysiologic procedures and perform many of the procedures as a part of this training while being overseen by experienced electrophysiologists. The main finding of this study is that the use of active esophageal cooling was associated with shorter procedure times and less variability around procedure times. Leveraging expertise from trained informaticists ensured accuracy in data identification and facilitated the data acquisition.
The reduction in procedure time and the variability around procedure time offers several benefits. Better predictability of procedure duration improves hospital scheduling, and reducing procedure times may allow additional cases to be scheduled, further improving hospital operations. More importantly, patient risk is reduced as procedure time is shortened. Increased operative duration, in general, increases the risk of complications such as surgical site infections, venous thromboembolism, bleeding, pneumonia, urinary tract infections, renal failure, and hematoma formation18. The likelihood of developing a complication increases with increasing operative time increments (i.e., 1% for every 1 min, 4% for every 10 min, 14% for every 30 min, and 21% for every 60 min increase in operative time)18. In the case of left atrial ablation, access time in the left atrium is the most significant procedural variable for the risk for post-operative cognitive dysfunction19.
A previous study in a community medical center also found procedural time savings associated with the use of active esophageal cooling during left atrial ablation for the treatment of atrial fibrillation9. The mechanism behind this effect relates to the elimination of frequent pauses from overheating that result in ablations and the temperature alarms that are utilized in LET monitoring. As active cooling eliminates overheating and therefore, the need for temperature alarms, it allows electrophysiologists to proceed without pauses20,21,22.
The critical steps in this protocol include properly identifying the individuals and their roles in the procedure to accurately record real-time field observations, probing to uncover any unconscious behaviors involved in experts&#39; workflows, and identifying specific elements of interest related to outcomes to determine where these variables are recorded and located in the Epic chronicles database. With careful completion of these steps, similar analyses can be undertaken for countless outcomes of interest.
The limitations of this analysis include the non-randomized allocation of patients and the retrospective collection of data recorded as the standard of care in the EHR. Although non-randomization introduces the potential for unmeasured confounders to influence results, no secular changes to treatment protocols occurred during the time period investigated in this analysis. Likewise, the use of data recorded as the standard of care in the hospital EHR may reduce the potential for bias in the data.
In conclusion, using contextual inquiry, workflow analysis, and data mapping to analyze procedural timing, this study demonstrated reduced procedure time and variability with active cooling when compared to traditional LET monitoring.

With a rise in the incidence of atrial fibrillation (AF) and an aging population, there is an increased demand for left atrial ablation to achieve pulmonary vein isolation (PVI) for the treatment of AF1. Optimizing procedure duration and minimizing variability are of increased interest among electrophysiologists and hospitals to meet population needs. During PVI procedures, one major risk is thermal injury to the esophagus due to the anatomical proximity of the left atrium to the esophagus2. Many methods exist to protect the esophagus from injury, including the current standard, luminal esophageal temperature (LET) monitoring, and other more recent developments including mechanical esophageal deviation and active esophageal cooling3.
Recent studies have found that LET monitoring may offer limited benefits over using no protection at all4,5,6. Additionally, LET monitoring necessitates frequent pauses of the procedure in response to luminal temperature alerts, which notify operators that the esophagus has reached dangerous temperatures. Recent data have shown that the distance between the temperature sensor and the radiofrequency (RF) catheter influences the sensitivity of LET monitoring, with greater than 20 mm of distance resulting in the absence of detection of significant temperature rises7. Moreover, large lag times (up to 20 s) in temperature rises and large gradients in temperature (up to 5 &#176;C) across the esophageal wall exist, further challenging the ability of LET monitoring to detect temperature elevations quickly enough to avert tissue damage8. Depending on the electrophysiology lab, the use of LET monitoring also requires frequent fluoroscopy exposure to patients and staff to reposition the temperature probe. These additional burdens may prolong the procedure, as reported in a recent study of a community hospital system in which a reduction in procedure duration when using active esophageal cooling instead of LET monitoring was found9.The use of active esophageal cooling allows the placement of contiguous point-to-point ablation lesions in the left atrium without the need to pause radiofrequency ablation due to temperature alarms or heat stacking. As a result, procedural pauses are reduced, and the contiguity of lesions is enhanced. This effect allows a reduction in procedure time and fluoroscopy time, and an improvement in the long-term efficacy of the ablation in reducing the recurrence of arrhythmias9,10,11,12,13.
As practice in an academic setting can vary drastically from a community hospital lab due to the introduction of trainees performing procedures while undergoing their education, the impact of the esophageal protection method is less certain. Moreover, advances in human factors analysis to ensure the identification of clinical data structures documenting the critical steps of each ablation case can be leveraged to facilitate studies of this type. Multiple individuals representing various specialties are involved during an ablation, making contextual inquiry useful for understanding the clinical workflows and pairing key activities with electronic health record (EHR) data structures14,15. Consequently, this study aimed to leverage medical informatics with contextual inquiry to compare the procedural efficiency of PVI procedures conducted with active esophageal cooling to those performed with LET monitoring.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<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>ensoETM</td>
			<td>Attune Medical, Chicago, IL</td>
			<td>ECD02A</td>
			<td>Active esophageal cooling device</td>
		</tr>
		<tr>
			<td>EPIC Clarity</td>
			<td>Epic System Corporation, Verona, WI</td>
			<td></td>
			<td>Electronic Health Record reporting database</td>
		</tr>
		<tr>
			<td>REDCap</td>
			<td>Nashville, TN</td>
			<td></td>
			<td>Secure web application for building and managing online surveys and databases, including compliance with 21 CFR Part 11, FISMA, HIPAA, and GDPR</td>
		</tr>
	</tbody>
</table>

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.

Patient characteristics 
In this analysis, a total of 164 patients were identified who underwent radiofrequency PVI between January 2020 and January 2022. Patients were included regardless of whether they received only PVI or received additional lesions such as roof lines, floor lines, mitral isthmus lines, etc. LET monitoring was performed with a single-sensor temperature probe and was performed by the same teams and in the same labs as the cases with active cooling. There were 63 patients who received LET monitoring for their PVI during the study period and 101 patients who received active esophageal cooling for esophageal protection. There were similar proportions of AF type in both groups (Table 1).
Procedure duration and procedure variability 
Procedure duration was defined as the time from the first sheath placed to the time of the last sheath removal. The mean procedure time in patients that underwent LET monitoring was 176 min &#177; 52 min. In the actively cooled group, the mean procedure time was 156 min &#177; 40 min, representing a 20 min overall reduction in procedure duration (P = 0.012). The median procedure time was 172 min (interquartile range [IQR] = 144 to 198 ) in the LET monitored group, and 151 min (IQR = 129 to 178 ; P = 0.025) in active esophageal cooling group. Overall, there was a median reduction of 21 min (FIGURE 1). Other than differences in the operator, no other factors differed between the groups other than the type of esophageal protection utilized. As such, the difference in procedural duration is believed to be due entirely to the pauses required with LET monitoring, reacting to temperature elevations, as well as the need to reposition repeatedly while ablating around the pulmonary veins. Although a long-term efficacy analysis has not yet been performed at this clinical site, data from elsewhere have shown improved efficacy with cooling when compared to LET monitoring. This is believed to be due to the improved point-to-point lesion sequencing that can be completed without interruption from local overheating alarms.
In the context of the technique described here, these results highlight the utility of the technique of workflow analysis, human factors analysis, and contextual inquiry to facilitate uncovering and analyzing data that can provide important insights into clinical practice. Traditional analyses of this type often rely on the manual extraction of large quantities of data, adding time and cost burdens to clinical investigations while reducing reliability and consistency. Incorporating advanced informatics techniques as described here opens new avenues for investigation without requiring extensive time and funding.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td></td>
			<td></td>
			<td colspan="2">Esophageal Protection</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td>Active Esophageal Cooling (n=101)</td>
			<td>LET Monitoring (n=63)&#160;</td>
		</tr>
		<tr>
			<td>Patient age (years), mean (SD)&#160;</td>
			<td></td>
			<td>67.9 &#177; 11.3</td>
			<td>64.5 &#177; 11.6</td>
		</tr>
		<tr>
			<td rowspan="2">Gender</td>
			<td>Male</td>
			<td>66</td>
			<td>46</td>
		</tr>
		<tr>
			<td>Female</td>
			<td>35</td>
			<td>17</td>
		</tr>
		<tr>
			<td rowspan="3">AF Type</td>
			<td>Paroxysmal Atrial Fibrillation</td>
			<td>55</td>
			<td>36</td>
		</tr>
		<tr>
			<td>Persistent Atrial Fibrillation</td>
			<td>38</td>
			<td>23</td>
		</tr>
		<tr>
			<td>Long-standing Persistent Atrial Fibrillation</td>
			<td>8</td>
			<td>4</td>
		</tr>
	</tbody>
</table>
Table 1: Patient characteristics, including age, gender, and type of atrial fibrillation treated. 
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/64417/64417fig01.jpg" /> 
Figure 1: Histogram comparing the procedure times of both groups. The green bars show patients receiving LET monitoring; the blue bars show patients receiving active esophageal cooling. Abbreviation: LET = luminal esophageal temperature. <a href="https://www.jove.com/files/ftp_upload/64417/64417fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Supplementary File 1: REDCap data storage extraction form. An example of the data extraction form used for this protocol, demonstrating the specific data elements recorded. <a href="https://www.jove.com/files/ftp_upload/64417/RedCap Form.pdf" target="_blank">Please click here to download this File.</a>

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

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 ...

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2.1K Views.  University of Texas Southwestern Medical Center. 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. 

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

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 ...

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 ...

Robotic Ablation of Atrial Fibrillation

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

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

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

Reduction of Iatrogenic Atrial Septal Defects with an Anterior and Inferior Transseptal Puncture Site when Operating the Cryoballoon Ablation Catheter

The cryoballoon catheter ablates atrial fibrillation (AF) triggers in the left atrium (LA) and pulmonary veins (PVs) via transseptal access. The typical transseptal puncture site is the fossa ovalis (FO) &#8211; the atrial septum&#8217;s thinnest section. A potentially beneficial transseptal site, for the cryoballoon, is near the inferior limbus (IL). This study examines an alternative transseptal site near the IL, which may decrease the frequency of acute iatrogenic atrial septal defect (IASD). Also, the study evaluates the acute pulmonary vein isolation (PVI) success rate utilizing the IL location. 200 patients were evaluated by retrospective chart review for acute PVI success rate with an IL transseptal site. An additional 128 IL transseptal patients were compared to 45 FO transseptal patients by performing Doppler intracardiac echocardiography (ICE) post-ablation to assess transseptal flow after removal of the transseptal sheath. After sheath removal and by Doppler ICE imaging, 42 of 128 (33%) IL transseptal patients demonstrated acute transseptal flow, while 45 of 45 (100%) FO transseptal puncture patients had acute transseptal flow. The difference in acute transseptal flow detection between FO and IL sites was statistically significant (P &#60;0.0001). Furthermore, 186 of 200 patients (with an IL transseptal puncture) did not need additional ablation(s) and had achieved an acute PVI by a &#8220;cryoballoon only&#8221; technique. An IL transseptal puncture site for cryoballoon AF ablations is an effective location to mediate PVI at all four PVs. Additionally, an IL transseptal location can lower the incidence of acute transseptal flow by Doppler ICE when compared to the FO. Potentially, the IL transseptal site may reduce later IASD complications post-cryoballoon procedures.

The goal of this study is to demonstrate the preferential location of transseptal puncture during a cryoballoon catheter ablation procedure for the treatment of atrial fibrillation.

The cryoballoon catheter ablates atrial fibrillation (AF) triggers in the left atrium (LA) and pulmonary veins (PVs) via transseptal access. The typical ...

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 ...

Focal Laser Ablation of Prostate Cancer: An Office Procedure

In this article, we describe and illustrate an outpatient procedure for focal laser ablation (FLA) of prostate cancer (PCa). The procedure is conceptually similar to a fusion biopsy and is performed under local anesthesia in a clinic setting; treatment time is usually less than one hour. Laser insertion is guided by ultrasound; lesion targeting is via magnetic resonance imaging-ultrasound (MRI/US) fusion, as in targeted prostate biopsy. Real-time ablation monitoring is achieved utilizing a thermal probe adjacent to the laser fiber. The video demonstrates procedure planning, patient preparation, various steps during the procedure, and treatment monitoring. Safety, feasibility, and efficacy of this approach have been established during a previous trial. Outpatient FLA under local anesthesia is an option for management of intermediate risk prostate cancer.

This article presents and describes an outpatient treatment for prostate cancer using focal laser ablation. Laser catheter placement is guided by MRI-ultrasound fusion imaging in a fashion similar to prostate needle biopsy. Treatment is monitored in real-time with a thermal probe, placed adjacent to the laser fiber.

In this article, we describe and illustrate an outpatient procedure for focal laser ablation (FLA) of prostate cancer (PCa). The procedure is conceptually ...

Sterile Pericarditis in Aachener Minipigs As a Model for Atrial Myopathy and Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia caused by structural remodeling of the atria, also called atrial myopathy. Current therapies only target the electrical abnormalities and not the underlying atrial myopathy. For the development of novel therapies, a reproducible large animal model of atrial myopathy is necessary. This paper presents a model of sterile pericarditis-induced atrial myopathy in Aachener minipigs. Sterile pericarditis was induced by spraying sterile talcum and leaving a layer of sterile gauze over the atrial epicardial surface. This led to inflammation and fibrosis, two crucial components of the pathophysiology of atrial myopathy, making the atria susceptible to the induction of AF. Two pacemaker electrodes were positioned epicardially on each atrium and connected to two pacemakers from different manufacturers. This strategy allowed for repeated non-invasive atrial programmed stimulation to determine the inducibility of AF at specified time points after surgery. Different protocols to test AF inducibility were used. The advantages of this model are its clinical relevance, with AF inducibility and the rapid induction of inflammation and fibrosis-both present in atrial myopathy-and its reproducibility. The model will be useful in the development of novel therapies targeting atrial myopathy and AF.

We describe a sterile pericarditis model in minipigs to study atrial myopathy and atrial fibrillation (AF). We present surgical and anesthetic techniques, strategies for vascular access, and a protocol to study the inducibility of AF.

Atrial fibrillation (AF) is the most common arrhythmia caused by structural remodeling of the atria, also called atrial myopathy. Current therapies only ...

Transesophageal Atrial Burst Pacing for Atrial Fibrillation Induction in Rats

Animal studies have brought important insights into our understanding regarding atrial fibrillation (AF) pathophysiology and therapeutic management. Reentry, one of the main mechanisms involved in AF pathogenesis, requires a certain mass of myocardial tissue in order to occur. Due to the small size of the atria, rodents have long been considered 'resistant' to AF. Although spontaneous AF has been shown to occur in rats, long-term follow-up (up to 50 weeks) is required for the arrhythmia to occur in those models. The present work describes an experimental protocol of transesophageal atrial burst pacing for rapid and efficient induction of AF in rats. The protocol can be successfully used in rats with healthy or remodeled hearts, in the presence of a wide variety of risk factors, allowing the study of AF pathophysiology, identification of novel therapeutic targets, and evaluation of novel prophylactic and/or therapeutic strategies.

The present work describes an experimental protocol of transesophageal atrial burst pacing for efficient induction of atrial fibrillation (AF) in rats. The protocol can be used in rats with healthy or remodeled hearts, allowing the study of AF pathophysiology, identification of novel therapeutic targets, and evaluation of new therapeutic strategies.

Animal studies have brought important insights into our understanding regarding atrial fibrillation (AF) pathophysiology and therapeutic management. ...