CS-ART042 Rev. 00©2019. CIRCA Scientific, Inc. All rights reserved.

ADVANCED TEMPERATUREMONITORING MATTERSDuring therapeutic procedures, esophageal temperatures can change quickly and unpredictably. Choose a temperature probe that gives your physicians the information they need to respond.

The esophagus lies in direct contact with the heart, subjecting it to rapid and potentially dangerous temperature changes during cardiac ablation procedures.1

To mitigate this risk, esophageal temperature monitoring has become standard-practice for most AF ablations performed today. Temperature monitoring provides feedback to physicians so that they can alter the procedure to avoid esophageal injury.2

Unfortunately, general purpose temperature probes are often used during these procedures – for a purpose they were not designed or intended for. These probes are designed to measure continuous core body temperature, not sudden temperature changes.2

CIRCA Scientific’s S-CATH™ is designed to provide faster, more accurate temperature detection. Featuring an array of 12 rapid-response temperature sensors that deploy throughout the length and width of the esophagus, the S-CATH™ provides responsive and accurate edge-to-edge coverage, enabling physicians to alter their procedures to minimize excessive heating or cooling of the esophagus.

THE IMPORTANCE OF ADVANCED TEMPERATURE MONITORING

WHY MONITOR ESOPHAGEAL TEMPERATURE?

The esophagus is located directly behind the left atrium of the heart.3

The esophagus is always in direct contact with the posterior wall of the left atrium and near the pulmonary veins – the primary targets of atrial fibrillation ablation.3,18,28 Furthermore, the esophagus is compressed by the spine or the aorta posteriorly, particularly when a patient is supine, increasing the surface area in contact with the posterior wall of the left atrium.28

There is very little tissue between these two structures to insulate the esophagus from temperature changes.3,28

As a result, the esophagus may be subjected to rapid, unpredictable, and potentially dangerous temperature changes during atrial fibrillation ablation procedures.1

Because of the close proximity of the esophagus to the left atrium and pulmonary veins, there is risk of collateral thermal injury to the esophagus during every atrial fibrillation ablation procedure.1 Research has shown that this risk exists regardless of operator experience or the thermal energy modality applied (e.g., radiofrequency, cryoballoon, or laser).4

ANATOMYTHE ESOPHAGUS & THE HEART

Injury to the esophagus is estimated to occur in 16-48% of ablations.5-9

Researchers have studied the incidence of esophageal injury following cardiac ablation in multiple clinical studies utilizing post-procedure endoscopy. Although results vary, these studies demonstrate that injury to the esophagus is common and occurs independently of the thermal energy used.5-9

Thermal esophageal injuries can be precursors to atrio-esophageal fistula.10

Thermal esophageal injuries range from mild erythema to deep ulceration. Severe injuries (ulcerations greater than 5 mm) have been associated with the development of the most feared complication of atrial fibrillation ablation: atrio-esophageal fistula.10-11, 29

THE RISK OFESOPHAGEAL THERMAL INJURY

32%36% 38% 40%

48% SAMPLES OF PUBLISHED RATES OFESOPHAGEAL THERMAL INJURYAFTER AF ABLATION

of patients undergoing cryoballoon ablation had esophageal lesions.8 (Rane et al., 2016; 48 patients)

of patients had esophageal injury without temperature monitoring after RF ablation.5 (Singh et al., 2008; 80 patients)

of patients had esophageal ulcerations following RF ablation.7 (Yokoyama et al., 2009; 20 subjects)

of patients either had esophageal lesions (28%) or ulcerations (12%) after standard RF ablation.6 (Tilz et al., 2012; 205 patients)

of patients had esophageal injury during RF ablation under general anesthesia.9 (Di Biase et al., 2009; 50 patients)

(Elsheshtawy et al., 2017)

Atrio-esophageal (AE) fistula is a fatal complication of atrial fibrillation catheter ablation, in which a direct connection forms between the esophagus and the left atrium.Although the pathophysiology is not fully understood, “it is clear that thermal injury to the esophagus during ablation of the left atrial posterior wall plays a crucial role in triggering the cascade of events that eventually result in the development of AE Fistula.”5

AE Fistula is believed to occur in 1 in 1,000 ablations with contact force sensing catheters.12

However, it is widely accepted that the incidence of this serious complication is underreported.13

Despite its rarity, prevention of this complication is critical due to the fact that AE Fistula is associated with a mortality rate as high as 80%.14

ATRIO-ESOPHAGEAL FISTULAA FATAL COMPLICATION

Multiple studies have demonstrated that accurate temperature monitoring offers clinicians an effective method for reducing the incidence of esophageal injury.19-20

Halm et al published research in 2009 that aimed to define luminal esophageal temperature thresholds at which injury occurs.19 They demonstrated that:

• Esophageal temperature monitoring with a multi-sensor probe reduced the risk of esophageal damage.

• Esophageal temperature of 41°C was a significant predictor of esophageal injury. • For every 1°C increase in luminal esophageal temperature, the odds of esophageal

lesion formation increase by a factor of 1.36X.

Similarly, Fürnkranz et al studied the effects of temperature monitoring during cryoablation.20 They concluded that:

• A strategy of esophageal temperature-guided cryoablation significantly reduced the incidence of esophageal lesions from 18.8% to 1.5% when a 15°C cutoff was used.

• The sensitivity of a 15°C cutoff temperature was further demonstrated when they investigated a more aggressive cutoff temperature of 12°C. This 3°C difference resulted in an increase of esophageal lesion incidence to 7.1%.

It is important to note that these studies were performed using a fast-response temperature monitoring system designed specifically for application during ablation procedures, NOT a single-sensor general purpose temperature probe which would have had a slower response rate and, as a result, may have underestimated peak esophageal temperatures.24

THE IMPORTANCE OF TEMPERATURE MONITORINGTO MINIMIZE ESOPHAGEAL INJURY

ALTHOUGH THE INCIDENCE RATE FOR ATRIO-ESOPHAGEAL FISTULA FORMATION

IS REPORTED TO BE LESS THAN 1%,

ATRIO-ESOPHAGEAL FISTULA IS ASSOCIATED

WITH AN 80% MORTALITY RATE.14

Nandavaram et al (2014)

THE INCIDENCE OF ATRIO-ESOPHAGEAL FISTULA IS LOW, BUT IS

BELIEVED TO BE UNDERREPORTED.13

Ellis et al (2012)

ONE HIGH-VOLUME CENTER REPORTED

2 ATRIO-ESOPHAGEAL FISTULAS IN 1,000

CONSECUTIVE PATIENTS.15

Dagres et al (2006)

ANOTHER CENTER RECENTLY REPORTED A RATE OF

1 ATRIO-ESOPHAGEAL FISTULA PER 572

PATIENTS UNDERGOING FIRST-TIME RF

ABLATION.17

Kim et al (2018)

A RECENT STUDY REPORTED 3 ATRIO-ESOPHAGEAL FISTULAS IN PATIENTS

UNDERGOING CRYOBALLOON ABLATION. THE AUTHORS NOTED THAT

TEMPERATURE MONITORING WAS NOT

EFFECTIVELY PERFORMED DURING ANY OF THE

PROCEDURES.17

Kawasaki et al (2014)

A COMPARISON OF ESOPHAGEAL TEMPERATURE MONITORING TECHNOLOGIES

SINGLE-SENSOR PROBES VS. CIRCA S-CATH™

Multiple studies have shown that accurate temperature measurement is largely dependent upon the proximity of the temperature sensor to the origin of greatest temperature change.4,21-23 These studies show that variations as small as 3-5 mm can have a dramatic impact on the accuracy of temperatures recorded.21

SENSOR LOCATION

Basic Probe S-CATH™ Probe

Active Sensor Average Esophageal Width: 18.9 mm

CIRCA S-CATH™... provides edge-to-edge coverage.Its unique S-shaped design deploys an array of 12 rapid-response sensors throughout the length and width of the esophagus to reliably and completely cover the esophageal tissue behind the left atrium.

The flexible probe naturally conforms to each patient’s unique anatomy, ensuring that a sensor is always located near the source of temperature changes without the need to attempt repositioning during the procedure.

SINGLE-SENSOR PROBES... only cover a small surface area.Peak temperatures are usually recorded in only a small area and are likely to be missed by a single temperature sensor.22 The small surface area covered by single-sensor probes does not adequately cover the length or width of the esophagus, which is at least 18 mm wide.28

... are prone to lateral (side-to-side) positioning.Studies show that 57% of the time, a straight probe will be located either to the far right or right side of the esophagus, rather than in the middle of the esophageal lumen.23 While operators can manipulate the vertical position of straight probes, the lateral position is impossible to control.23 The resulting distance of the probe from the source of temperature changes has a significant impact on the accuracy of esophageal temperatures measured.23

The 2017 Global Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation cautioned that “because the esophagus is broad, the lateral position of the temperature probe might not align with the ablation electrode, and the operator could receive a false impression of safety.”4

CLINICAL DATA

FASTER DETECTION MORE COMPLETE COVERAGEIn a recently published study, researchers showed that CIRCA Scientific’s S-CATH™ began to show an initial temperature rise 17 seconds faster than a 9F single-sensor probe.25

17 Seconds Faster To Detect Initial Temperature Rise

Single-Sensor Probe (9F) 30.5 ± 15.4 sec

CIRCA S-CATH 13.4 ± 7.5 sec

In the same study, researchers found that 9F single-sensor temperature probes missed 90% of temperature rises ≥2°C recorded by CIRCA S-CATH,™ which were interpreted to be critical by the authors.25

90%Single-Sensor Missedof temperature rises ≥2°C

Single-Sensor Probe (9F) 4

CIRCA S-CATH 40

28

SENSOR RESPONSIVENESS

SINGLE-SENSOR PROBES CIRCA S-CATH™

... are designed to measure gradual changes in core body temperature, not sudden temperature changes.The construction of these probes places the thermistor in the center of the probe under at least 2 layers of thick insulating plastic with significant air gaps between each layer. These insulating layers make these probes slow-to-respond to the rapid temperature changes that are common during therapeutic procedures.2

... is designed to promote rapid temperature detection.The S-CATH’s design places its thermistors in direct contact with a thin metal band near the surface of the probe to promote rapid temperature transfer and detection.

To be effective, esophageal temperature probes must accurately reflect esophageal tissue temperature. Multiple studies have shown that single-sensor probes are remarkably insensitive to abrupt temperature changes and significantly underestimate peak esophageal temperatures when utilized during cardiac ablation procedures.2

Construction of General-Purpose Temperature Probes

Outer PVC Layer

Air Gap

Hard Plastic Capsule

Air Gap

Thermistor

Epoxy Core

Studies show that CIRCA Scientific’s S-CATH™responds to temperature changes 2X faster than 9F general purpose temperature probes and 8X faster than 18F esophageal stethoscopes.24

BETTER CLINICAL DECISIONS FEWER LESIONSAnother study reviewed esophageal injury rates in 40 patients who underwent endoscopy post-ablation. Using CIRCA S-CATH™ to guide ablation energy delivery with a specified temperature cutoff of 39°C, only 1 of 40 patients developed evidence of esophageal thermal injury.26

1:4026

Study showed reduced rate of esophageal injury when RF ablation was guided by CIRCA S-CATH™.

At HRS 2017, researchers presented data on AF Ablation patients who were either monitored with CIRCA S-CATH™ or a single-sensor probe. This data showed that only 1/16 patients who were monitored with CIRCA S-CATH had an esophageal lesion after the procedure (vs. 23/69 who were monitored with a single-sensor probe).27

6% vs. 33%

Patients monitored with CIRCA S-CATH vs. Single-Sensor Probe

(Gianni et al., 2018)

Indications for Use: The CIRCA S-CATH Esophageal Temperature Probe is intended for continuous temperature monitoring. The radiopaque probe is designed for placement in the esophagus. The CIRCA Temperature Monitor is indicated to display continuous temperature measurement (°C) from 12-sensor temperature probe.

Caution: Federal (U.S.A.) law restricts this device to sale by or on the order of a physician.

References

1. Elsheshtawy, M., et al. “The Esophagus and Atrial Fibrillation: Anatomical Considerations and Practices.” EP Lab Digest (2017): 22-25.

2. Gianni, C., et al. “Difference in thermodynamics between two types of esophageal temperature probes: Insights from an experimental study.” Heart Rhythm 13.11 (2016): 2195-2200.

3. Sánchez-Quintana, D., et al. “Anatomic relations between the esophagus and left atrium and relevance for ablation of atrial fibrillation.” Circulation 112.10 (2005): 1400-1405.

4. Calkins, H., et al. “2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation.” Heart Rhythm 14.10 (2017): e275-e444.

5. Singh, S. M., et al. “Esophageal Injury and Temperature Monitoring During Atrial Fibrillation Ablation.” Circulation Arrhythmia and Electrophysiology 1.3 (2008): 162-168.

6. Tilz, R. R., et al. “Catheter Ablation of Long-Standing Persistent Atrial Fibrillation: A Lesson from Circumferential Pulmonary Vein Isolation.” Journal of the American College of Cardiology 21.10 (2012): 1085-1093.

7. Yokoyama, K., et al. “Canine Model of Esophageal Injury and Atrial-Esophageal Fistula After Applications of Forward-Firing High-Intensity Focused Ultrasound and Side-Firing Unfocused Ultrasound in the Left Atrium and Inside the Pulmonary Vein.” Circulation Arrhythmia and Electrophysiology 2.1 (2009): 41-49.

8. Rane, S., et al. “Incidence of Esophageal Thermal Injury with Cryoballoon and Contact Force Radiofrequency Ablation .” Heart Rhythm Scientific Sessions. San Francisco, CA, 2016.

9. Di Biase, L., et al. “Esophageal Capsule Endoscopy After Radiofrequency Catheter Ablation: Documented Higher Risk of Luminal Esophageal Damage with General Anesthesia as Compared With Conscious Sedation.” Circulation Arrhythmia and Electrophysiology 2.2 (2009): 108-112.

10. Yarlagadda, B., et al. “Temporal Relationships between Esophageal Injury Type and Progression in Patients Undergoing Atrial Fibrillation Catheter Ablation.” Heart Rhythm (2018).

11. Elrod, J. “Best Practices for Avoiding Esophageal Injury: Interview with Vivek Reddy, MD.” EP Lab Digest 14.5 (2014).

12. Perf. Douglas L. Packer. Get In Rhythm, Stay In Rhythm, Dallas. 2017.13. Ellis, C. R., et al. “Successful Treatment of Esophageal Perforation Following Atrial

Fibrillation Ablation with a Fully Covered Esophageal Stent: Prevention of Atrial-Esophageal Fistula.” The Journal of Innovations in Cardiac Rhythm Management 3 (2012): 874-878.

14. Nandavaram, Sravanthi. “Atrio-Esophageal Fistula Fatal Complication of Radiofrequency Ablation of Atrial Fibrillation.” Chest 145.3, Supplement (2014): 75A.

15. Cabrera. J. A. “Anatomical Considerations of the Esophagus and Left Atrium.” Boston, MA, May 2018. HRS Presentation.

16. Dagres, N., et al. “Rapid detection and successful treatment of esophageal perforation after radiofrequency ablation of atrial fibrillation: lessons from five cases.” Journal of Cardiovascular Electrophysiology 17.11 (2006): 1213-1215.

17. Kim , Y. G.., et al. “Characteristics of atrial fibrillation patients suffering atrioesophageal fistula after radiofrequency catheter ablation.” Journal of Cardiovascular Electrophysiology 29.10 (2018): 1343-1351.

18. Kawasaki, R., et al. “Atrioesophageal Fistula Complicating Cryoballoon Pulmonary Vein Isolation for Paroxysmal Atrial Fibrillation.” Journal of Cardiovascular Electrophysiology 25.7 (2014): 787-792

19. Halm, U., et al. “Thermal Esophageal Lesions After Radiofrequency Catheter Ablation of Left Atrial Arrhythmias.” The American Journal of Gastroenterology 105 (2010): 551-556.

20. Fürnkranz, A., et al. “Luminal esophageal temperature predicts esophageal lesions after second-generation cryoballoon pulmonary vein isolation.” Heart Rhythm 10.6 (2013): 789-793.

21. Merino, J. L., et al. “Sensitivity and Accuracy of Sensitherm/Esotherm Oesophageal Temperature Probe: Reply.” EP Europace 18.3 (2016): 468-469.

22. Nakagawa, H., K. A. Seres and W. M. Jackman. “Limitations of Esophageal Temperature-Monitoring to Prevent Esophageal Injury During Atrial Fibrillation Ablation.” Circulation: Arrhythmia and Electrophysiology 1.3 (2008): 150-152.

23. Knecht, S., et al. “Reliability of Luminal Oesophageal Temperature Monitoring During Radiofrequency Ablation of Atrial Fibrillation: Insights From Probe Visualization and Oesophageal Reconstruction Using Magnetic Resonance Imaging.” EP Europace 19.7 (2017): 1123-1131.

24. Gianni, C., et al. “Thermodynamic characteristics of a multi-sensor esophageal temperature probe.” 2018. Poster Presented at AHA 2018.

25. Tschabrunn, C. M., et al. “Comparison between single- and multi-sensor esophageal temperature probes during atrial fibrillation ablation: thermodynamic characteristics.” EP Europace 17.6 (2015): 891-897.

26. Halbfass, P., et al. “Incidence of asymptomatic oesophageal lesions after atrial fibrillation ablation using an oesophageal temperature probe with insulated thermocouples: a comparative controlled study.” Europace 19 (2017): 385-391.

27. Moura, D. M. C., et al. “Incidence of Esophageal Thermal Injury After Atrial Fibrillation Catheter Ablation.” Boston, MA, May 2017. HRS 2017 Poster.

28. Cury, R. C., et al. “Relationship of the esophagus and aorta to the left atrium and pulmonary veins: implications for catheter ablation of atrial fibrillation.” Heart Rhythm 2.12 (2005): 1317-1323.

29. Deneke, T., et al. “High-Resolution Infrared Thermal Imaging of the Esophagus During Atrial Fibrillation Ablation as a Predictor of Endoscopically Detected Thermal Lesions.” Circulation: Arrhythmia and Electrophysiology 11 (2018): 1-9.

30. Singh, S. “Atrio-Esophageal Fistula: Anatomy and Mechanism.” Heart Rhythm Scientific Sessions. Boston, MA, 2018.

CIRCA S-CATH BENEFIT

• The esophagus is at risk of thermal injury during most left atrial ablation procedure, regardless of thermal energy used or operator experience.5-9

• Multiple studies have demonstrated that accurate temperature monitoring offers clinicians an effective method for reducing the incidence of esophageal injury.19-20, 26-27

• While general purpose temperature probes are commonly utilized to monitor esophageal temperature during ablation procedures, they are ill-suited to detect sudden temperature changes and do not adequately cover the length or width of the esophagus behind the left atrium.2,4,21-25

• CIRCA Scientitifc’s advanced temperature monitoring tools rapidly and accurately detect temperature changes and provide broad coverage of the esophagus behind the left atrium, giving physicians the information they need to alter their procedures to minimize excessive heating or cooling of the esophagus.