In a regularly beating heart, a group of cells at the sino-atrial (SA) node, the body’s natural “pacemaker,” sends out an electrical signal that travels through the heart. The impulses spread through the right and left atria, causing them to contract evenly. The atrio-ventricular (AV) node activates, conducting the signal down into the ventricles. In a heart with atrial fibrillation (AFib), electrical short circuits develop and cause the atria to beat erratically. The contraction of the atria and ventricles is no longer coordinated. Consequently, blood may not be pumped as effectively through the heart and to the body.
Figure 1. Left: heart with normal electrical conduction. Right: heart with atrial fibrillation. Multiple electrical impulses start from a different location than the SA node and follow abnormal pathways. (Alila Medical Media)
For patients with AFib who are not responsive to medication, an ablation may be the next step. An ablation is a minimally invasive procedure that works to treat AFib by intentionally removing (electrically isolating) the areas of the atria that trigger atrial fibrillation – the pulmonary veins.
At UCSF, thousands of ablation procedures are conducted each year. There are various ways that an ablation can be done. The most common approach, called radiofrequency ablation (RFA), involves threading a small catheter into the heart and using radiofrequency energy to gently burn the abnormal tissue. An alternative method, called balloon cryoablation, freezes the tissue instead of using heat. This procedure involves inserting a thin, flexible tube called a balloon catheter through a blood vessel to reach the damaged area. The catheter then freezes the tissue.
More recently, a newer, safer, and equally effective procedure has been developed called Pulsed Field Ablation (PFA). PFA differs from conventional thermal ablation, as it uses electrical fields to ablate heart tissue rather than “heat” or “cold.” This greatly mitigates the risk of damage to structures surrounding the heart, such as nerves or the esophagus (swallowing tube). Dr. Edward Gerstenfeld, one of the principal investigators of the BEAT-AFib Study, has led UCSF in a multicenter study called ADVENT to determine if this is true. The study concluded that PFA is similarly as safe as thermal ablation and may be more effective at preventing recurrent AFib.
Click here to read more about the results of the ADVENT study!
References
- Mohen, L. (n.d.). Atrial Fibrillation Ablation. Melbourne Heart Rhythm. https://www.melbourneheartrhythm.com.au/learn/procedures/13-atrial-fibrillation-ablation?showall=1
- Reddy, V. Y., Gerstenfeld, E. P., Natale, A., Whang, W., Cuoco, F. A., Patel, C., Mountantonakis, S. E., Gibson, D. N., Harding, J. D., Ellis, C. R., Ellenbogen, K. A., DeLurgio, D. B., Osorio, J., Achyutha, A. B., Schneider, C. W., Mugglin, A. S., Albrecht, E. M., Stein, K. M., Lehmann, J. W., & Mansour, M. (2023). Pulsed Field or Conventional Thermal Ablation for Paroxysmal Atrial Fibrillation. New England Journal of Medicine, 389(18), 1660–1671. https://doi.org/10.1056/nejmoa2307291
