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2022 AF Symposium
Pulsed Field Ablation for AF Using an Integrated Mapping and Ablation Spherical Array Catheter
Note: This was a very early, first-in-human use of this Spherical Array PFA catheter not yet approved by the FDA
Dr Vivek Reddy
Dr. Vivek Reddy from Mount Sinai Medical Center in New York City, NY and Dr. Petr Neuzil of Homolka Hospital, Prague, Czech Republic presented a pre-recorded case on “Pulsed Field Ablation for AF Using an Integrated Mapping and Ablation Spherical Array Catheter.”
The patient was a 31-year-old male diagnosed with paroxysmal A-Fib in 2020. His left atrium diameter measured 39 mm (normal size). His Ejection Fraction was 65% (normal). His CHA2DS2-VASc score was zero.
Innovative Spherical Array
Dr. Reddy showed a fascinating demo of how the spherical PFA catheter emerged from the catheter sheath and formed itself into a spherical array, then locked itself into shape. It was like watching a magic trick. How could they design a catheter sheath from which would emerge a complex spherical shaped catheter that would come together so smoothly? Kudos to whomever designed this innovative system (Kardium Globe).
How the Spherical Array Catheter Works
Once fully deployed, the spherical PFA catheter has a diameter of 30 mm. It contains 122 gold-plated electrodes on 16 splines around the sphere. Behind each electrode is a thermocouple to measure heat. (The system was originally designed for RF ablation. But this spherical catheter was not irrigated.) Because of the high number of electrodes, it also produces high quality 3D activation maps of the left atrium. It can also be used for pacing.
Spiral Array Catheter at opening to Pulmonary Vein
As we watched, Dr. Reddy easily rotated and moved the Spherical Array catheter. It can map and ablate anywhere is the left atrium and produce continuous lesions. It doesn’t have to be manipulated as much as a point-by-point RF catheter. The next generation catheter will be smaller.
The system is bi-polar and biphasic in that the PFA signal is delivered using an electrode on one spline along with another electrode on an adjacent spline. Usually, Dr. Reddy said, he only required a 3-second PFA ablation to isolate a PV.
They used general anesthesia, but acknowledged that this system could work under simple conscious sedation.
Single-Shot, Omni-Directional, Needs Tissue Contact
Dr. Reddy described it as a single shot system in that one PFA application should isolate an area. It is omni-directional in that the sphere can be positioned in any direction as long as there is contact, and the sphere is touching tissue. The system seemed to easily produce a voltage map of the left atrium. The system uses GPS 3D navigation and mapping to track the precise location of the Globe catheter inside the atrium.
“Flow” and “Contact” Mapping: Where to Apply the PFA Pulse
Dr. Reddy described the system as using two types of contact mapping: “Flow” Map and “Contact” Mapping.
The Flow Map gets contact info relatively fast by sensing how quickly the electrodes cool when electricity is applied to them, while Contact Mapping takes 10-15 seconds and calculates how high the temperature rises. If it touches tissue, the temperature should become higher. “Contact” mapping provides more high-fidelity info than “Flow” mapping.
Dr. Reddy would use both systems one after the other to determine where the actual PFA pulse should be applied. Dr. Reddy said that the Spherical Array catheter is in one sense a large focal catheter while also more forgiving in terms of precise positioning. When a green area appeared, this meant contact. While white represented areas not yet ablated. Blue areas represented completed PFA lesions.
We watched as the PVs were isolated. He showed both pre and post voltage maps side-by-side to document that the PVs were isolated. Some microbubbles were produced, but previous RF ablations using this system didn’t produce any problems. Dr. Reddy said that they haven’t seen any reconnection. In this case they only isolated the PVs and made no attempt to isolate the posterior left atrium wall or other areas of the heart.
Removing the Spherical Array Catheter
At the end we watched as Dr. Reddy forced the catheter shaft back over the Spherical Array which collapsed back into a linear form and was easily removed (another fascinating technical achievement).
