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.
Atrial Fibrillation (AFib)
Atrial fibrillation is due to abnormal chaotic electrical activity in the upper chambers of the heart known as atria. It is the most common heart rhythm disturbance. While it is more common in men, approximately 26% of men and 23% of women will have atrial fibrillation by the age of 80 (1). This creates three separate issues: risk of stroke, fast heart rates, and symptoms. This is a progressive disease with initially paroxysmal atrial fibrillation (episodes that are recurrent but stop on their own) that progress to persistent atrial fibrillation (episodes that require medical intervention to stop) and eventually permanent atrial fibrillation. It is easier to maintain normal rhythm if medical treatment to maintain normal rhythm is started early in the paroxysmal stage with anti-arrhythmic therapy (medications that help reduce episodes of atrial fibrillation) or pulmonary vein isolation (a procedure to stop atrial fibrillation). For patients with more advanced disease (persistent atrial fibrillation), there are new advances on the horizon including the convergent procedure (2).
- DeLurgio DB, Ferguson E, Gill J, Blauth C, Oza S, Mostovych M, Awasthi Y, Ndikintum N, Crossen K. Convergence of Epicardial and Endocardial RF Ablation for the Treatment of Symptomatic Persistent AF (CONVERGE Trial): Rationale and design. Am Heart J. 2020 Jun;224:182-191. doi: 10.1016/j.ahj.2020.02.016. Epub 2020 Feb 29. PMID: 32416333.
- Magnani JW, Rienstra M, Lin H, Sinner MF, Lubitz SA, McManus DD, Dupuis J, Ellinor PT, Benjamin EJ. Atrial fibrillation: current knowledge and future directions in epidemiology and genomics. Circulation. 2011 Nov 1;124(18):1982-93. doi: 10.1161/CIRCULATIONAHA.111.039677. PMID: 22042927; PMCID: PMC3208425.
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.