Atrial Fibrillation (AFib)
Radio-Frequency Energy (RF)
The very first technology that was used for this was radio-frequency energy (RF) which is similar to the energy that your microwave oven uses to heat up food. This requires maneuvering a wire in the heart and making dots around the pulmonary veins. As the opening of the pulmonary veins is a circular shape, a circle is made with the dots. When the dots are all connected together, a circle is made around the vein blocking electricity from entering the heart. A newer technology (cryoballoon) uses a balloon that is inflated in the heart, placed at the opening of the pulmonary vein, and then cooled (usually around -45C or -49F) to create a scar and block abnormal electrical signals. This makes a perfect circle with one treatment instead of having to connect many dots to draw a circle. In a recent trial (3) published in 2021, this was successful in 75% of patients while medications and anti-arrhythmic therapy was only 45% effective. There have been trials comparing cryoballoon to traditional RF ablation and the success rate are similar (4). However, the advantage of the cryoballoon is shorter procedure time and that “cold energy” creates less char than RF energy.
- Wazni OM, Dandamudi G, Sood N, Hoyt R, Tyler J, Durrani S, Niebauer M, Makati K, Halperin B, Gauri A, Morales G, Shao M, Cerkvenik J, Kaplon RE, Nissen SE; STOP AF First Trial Investigators. Cryoballoon Ablation as Initial Therapy for Atrial Fibrillation. N Engl J Med. 2021 Jan 28;384(4):316-324. doi: 10.1056/NEJMoa2029554. Epub 2020 Nov 16. PMID: 33197158.
- Kuck KH, Brugada J, Fürnkranz A, Metzner A, Ouyang F, Chun KR, Elvan A, Arentz T, Bestehorn K, Pocock SJ, Albenque JP, Tondo C; FIRE AND ICE Investigators. Cryoballoon or Radiofrequency Ablation for Paroxysmal Atrial Fibrillation. N Engl J Med. 2016 Jun 9;374(23):2235-45. doi: 10.1056/NEJMoa1602014. Epub 2016 Apr 4. PMID: 27042964.
Pulmonary Vein Isolation, Catheter Ablation for Atrial Aibrillation
Catheter ablation is a procedure that uses energy (radio-frequency, cold, high frequency ultrasound, laser, etc…) to block abnormal heart rhythms. Pulmonary vein isolation is a type of catheter ablation for the heart. Most paroxysmal atrial fibrillation starts in the pulmonary veins. These are blood vessels located in the back of the upper left chamber of the heart (left atrium). With pulmonary vein isolation (PVI), energy is used to create scar in the heart to block the abnormal electrical signals from the pulmonary veins from entering the heart.
At present, there is only one company (Medtronic) that manufactures a commercially available cryoballoon for pulmonary vein isolation. There are other competing technologies, but these do not use cold energy and instead rely on heat (radio-frequency), laser, or high frequency ultrasound. There is a new technology on the horizon called electroporation that uses electrical pulses for catheter ablation. This is not yet approved for wide spread clinical use. Radio-frequency ablation has been around for many years and it is still the main type used for catheter ablation for heart rhythm disturbances other than atrial fibrillation. The heat generated with this energy creates scar. The versatility is that it can deliver one tiny spot or can be used to “draw” a line or circle.