2020 AF Symposium

Protecting the Esophagus by Cooling It

Mark Gallagher. MD

“We know that most strategies (to prevent fistula) don’t work,” Says Dr. Mark Gallagher from St. George’s University Hospital in London, United Kingdom.

Added: 9/16/22: Strategies to prevent Esophageal injury include:

1. Reducing power applied to the vulnerable regions (Lesions with lower power may not always be effectve.).

2. Monitoring Esophageal temperature, stopping the ablation when temperature rises. (A reactive approach of limited efficacy. By the time temperature rises, serious damage may have already been done to the esophagus.)

3. Deviating the esophagus during the ablation to bend it away from the area being ablated. (Can cause Esophageal trauma and involve difficulties in use. And requires procedural pauses for device manipulation.)

At the 2020 AF Symposium, Dr. Gallagher described an innovative strategy he and his colleagues developed to prevent fistula. He presented the completed IMPACT study which investigated whether Attune Medical’s ensoETM esophageal cooling system could effectively reduce the incidence and severity of thermal injuries to the esophagus during cardiac ablation.

IMPACT Double Blind Randomised Controlled Trial

In their clinical trial, Dr. Mark Gallagher and colleagues divided 120 patients into two groups: a control group and a experimental group.

The Control Group: The control group received only standard care, in this case a temperature probe in the esophagus. If the temperature in the esophagus went too high, they would stop the ablation till the temperature went back down (current practice).

This would often lead to the EP not being able to effectively isolate all A-Fib signal areas in the heart which were too close to the esophagus. And often, by the time the temperature went up, damage had already been done to the esophagus.

The Experimental Group: Patients in the second (experimental) group instead received a 3-foot long silicone soft tube in their esophagus connected to what was basically a refrigerator. This closed loop system pumped cooled water (25  ͦ F, 4  ͦ C) down one loop of the tube, then back through another loop to the console whenever the EP worked near the esophagus. The EP controls the temperature. Some centers are able to use this protocol under conscious sedation rather than general anesthesia.

Double-Blind for Both Operators and Evaluators

This was a double-blind study. The EP doing the ablation didn’t know if they were working on a Control or Experimental patient. And the doctors evaluating the procedure for possible esophagus damage also were blinded.

After 7 days, an endoscopy was performed on each patient’s esophagus (an endoscopy examines the inside of an organ). They were looking for lesions and for gastroparesis (delayed emptying of the stomach).

IMPACT Study Results

The Control group who received the standard temperature probe had multiple epithelial lesions, while the Experimental group who experienced the closed loop cooling system had only one minor lesion. They found a “statistically significant 83% reduction in endoscopically identified lesions when using a dedicated cooling device compared to standard LET monitoring”

The Experimental group also needed less fluoroscopy (X-ray) time. And, more importantly, the EP was able to ablate longer in areas near the esophagus (such as the posterior wall of the left atrium). That improved the success rate of the ablation and ablation efficacy.

Added: 9/16/22:

In an article by Zagrodzky et al, when protecting the esophagus during RF ablation, they found a 61% reduction in high-grade lesion formation in a total of 494 patients.

Editor’s Comments

Most fistula patients die. And for those who live through the emergency treatment, they are often compromised for life. But with the esophageal cooling system, patients and doctors may never again have to worry about the dreaded complication Atrial-Esophageal Fistula!

Cooling the Esophagus, a Major Medical Breakthrough! Cooling the esophagus is simple and relatively easy to do. And, barring future research findings, it seems full proof.

The Attune Medical’s ensoETM esophageal cooling system is certainly cheaper than having to care for patients with a fistula.

The Attune Medical ensoETM esophageal cooling system can provide both cooling during RF ablation, and heating during Cryo ablation.

Probably among the major proponents of the esophagus cooling system will be hospital administrators. Treating patients with a fistula is a huge expense and a nightmare for hospital staff.

A fistula is an all-hands-on-deck emergency involving not just the EP department but surgeons and many hospital staffers. A surgeon may have to perform emergency surgery to insert stents in the esophagus in order to close off the fistula, or the surgeon may have to cut out part of the damaged esophagus, which is particularly risky

(I remember one EP describing how he and his staff were running down a hospital corridor with their fistula patient close to dying, in order to get the patient to an operating surgeon.).

Esophageal Cooling Means Better Ablations: And as a bonus, using the esophageal cooling system enables EPs to do a more thorough better job. They can ablate all areas of the heart rather than avoiding areas too close to the esophagus or using lower power with shorter duration or less contact force.

When Will Esophageal Cooling be Available? For catheter ablation application, probably not soon. In the U.S and probably worldwide, Attune Medical’s ensoETM esophageal cooling system is already in use and approved for specific purposes, for example, in cases of brain damage where a patient needs to have their whole body cooled down. But not for catheter ablation

In the United Kingdom, it will first have to be approved by NHS. In the U.S., it may not need to go through the FDA approval process again. (But this is a very speculative observation.)

Will Ablation Centers Implement? It will probably require a great deal of marketing to make EPs and ablation centers aware of and actually start using the esophageal cooling system. And because Atrial-Esophageal Fistula is such a rare complication, centers may not be willing to invest in an esophageal cooling system.

If you find any errors on this page, email us. Y Last updated: Saturday, September 17, 2022

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