AF Symposium 2020

Live Case: Ultra-Low Temperature Cryoablation

Background: The Adagio Medical iCLAS catheter is a Cryo catheter that uses ultra-low temperatures and is unlike anything currently on the market. To learn more about the iCLAS catheter, see my earlier report from the 2018 AF Symposium: Innovative iCLAS Cyro Catheter by Adagio Medical.

Note: The Adagio Medical iCLAS is not yet FDA approved. The U.S. IDE study trial is active and enrolling. The clinical trial started in December 2019. https://clinicaltrials.gov/ct2/show/NCT04061603.

Live Ablation Via Streaming Video

Live from Belgium, Dr. Tom De Potter and his colleagues from OLV Hospital performed an ablation using Adagio Medical’s ultra-low temperature cryoablation catheter.

When the Symposium audience joined the live ablation via streaming video, Dr. De Potter and his colleagues had already performed a single transseptal puncture and were working in the left atrium.

To produce temperatures as low as (minus) –196° Celsius, Adagio Medical uses what they call Near Critical Nitrogen (NCN) which is far lower than current CryoBalloon technologies.

Producing Continuous Linear Ablations

Adagio catheters produce continuous linear ablations and can also be configured to do focal (single point) catheter lesions. Dr. De Potter also showed how the same Adagio Medical catheter can also do cryo mapping.

As we watched, Dr. De Potter encircled the Left Superior Pulmonary Vein (PV) with a double loop catheter. Then applied the cryo energy and froze the ostium area to isolate the PV. The catheter stylus included a loop of the freezing section and a loop with electrodes which recorded/mapped the A-Fib signals.

Freezing Isolated the Vein

We could see the ice formation on the catheter itself and how the freezing isolated the vein.

It only took 30 seconds to isolate that vein, but Dr. De Potter continued the freeze for one minute. Then performed what he called a bonus freeze.

On the catheter monitor, we could see how that vein had PV potentials which were then isolated.

Then Dr. De Potter moved to the Right Pulmonary Veins. The phrenic nerve usually runs close to the ostia of the right PVs. He said they perform phrenic nerve pacing to prevent damage to the phrenic nerve. We saw how they performed phrenic nerve capture.

Monitoring the Phrenic Nerve

If they do find they might be damaging the phrenic nerve, they don’t ablate there or insert a different catheter stylus configuration which doesn’t affect that area.

They didn’t achieve isolation of the Right Interior PV, so they did a second ablation while slightly changing the stylus loop position. Dr. De Potter said that he usually achieves isolation with one pass, except for, as in this case, with the Right Interior PV which is more challenging.

CryoAblation is Reversible. Dr. De Potter showed how they first used low energy cryo in a 30 second ablation to see if the phrenic nerve was affected (if affected, the tissue can be de-frosted and returned to normal or reversed.) Then they applied the full cryo energy at the ultra-low temperature which is permanent. The speed of decrease in cooling is very fast at 300°C/sec.

Protecting the Esophagus

To protect the esophagus, Dr. De Potter showed how they insert a warming balloon with constantly circulating warm saline into the esophagus which prevents excessive cooling and damage to the esophagus.

He stated that the next generation of the warming balloon will also have temperature sensing. They can then have a much better idea of what the freezing will do to the esophagus, how much temperature affects will be seen in the esophagus.

Ablating the Posterior Wall 

Dr. De Potter also showed the Adagio Medical system ablating the posterior wall. “It’s very simple. We will make overlapping rings.”

We saw him make those overlapping ring ablations in three passes which blocked conduction over the posterior wall. But with a larger atria, he may use 6 applications. He mentioned that at this stage he hasn’t achieved consistent success making a Mitral Isthmus line.

The Key Benefit of Ultra-Low Temperature Cryoablation

According to Dr. De Potter:

“The key benefit of this technology is a different energy source in contrast to the CryoBalloon which uses a theoretical minimum of –80°C.

This system (Adagio Medical) uses liquid nitrogen which has a theoretical minimum of –196°C. When you consider that this –80°C is at the center of the balloon and not necessarily at the tissue, we think we have a far better margin for efficient energy delivery while providing for patient safety.”

Editor’s Comments:

When I visited the Adagio booth at the Symposium exhibit hall, I was fascinated to see how easily the catheter can be manipulated into many different configurations depending on the lesions which need to be made.

Using its full length, the catheter can produce ultra-low temperatures along its whole span (110mm). Its 20 electrodes can also produce cryo-mapping of the atria.

Why is the iCLAS Cryo catheter special and innovative? The iCLAS catheter produces ablation lesions like current CryoBalloon catheters but at lower temperatures (colder). One would expect that such ultra-low Cryo lesions would be deeper, more transmural, and more lasting.

In addition, the ability to produce unlimited shapes gives the iCLAS catheter a unique ability to position Cryo lesions in a variety of locations in the heart.

The Adagio Medical iCLAS cyro system will make ablations much simpler and easier for EPs. It may eventually supersede normal CryoBalloon ablation (which is already a very effective ablation strategy).

If you find any errors on this page, email us. Y Last updated: Saturday, May 23, 2020

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