A cardioversion is a procedure that helps return the heart to a normal rhythm when it is beating too fast or irregularly, like in atrial fibrillation (AFib). There are two main types of cardioversions: medication-based and electrical. Medication-based, or chemical, cardioversion involves taking a medicine by mouth or through an IV to help fix the rhythm of the heart. Electrical cardioversion uses a quick, controlled electrical shock to reset the heart’s rhythm. This article will focus on electrical cardioversion.
During an electrical cardioversion, sticky pads are placed on the chest and sometimes on the back. These pads are connected to a machine that displays the heart’s rhythm and delivers a brief shock. An IV is placed so sedation can be given to help the patient relax or sleep during the procedure. A blood pressure cuff may also be used to monitor vital signs. The shock in an electrical cardioversion typically lasts less than one second. After the initial shock, the doctor will check to see if the heart has returned to a normal rhythm. In some cases, another shock (often at a higher “energy” level) may be necessary if the first shock does not work.
Figure 1: An electrical cardioversion procedure. Illustration by Jmarchn – National Heart Lung and Blood Institute (NIH),
CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=123849246
While a cardioversion itself lasts about 5 minutes, the total time of the entire procedure is around 30 minutes when including preparation and sedation. Patients often stay in the hospital for a few hours afterward so the care team can observe their heartbeats. Like any medical procedure, a cardioversion has some risks, but they are uncommon. One risk is that a blood clot in the heart could move to another part of the body. To help prevent this, patients are put on blood thinners for about 4 weeks prior to the procedure, or an ultrasound may be done before the procedure to look for clots. Further, patients are generally kept on blood thinners after the procedure for at least a month. Mild skin irritation from the pads can also occur.
Despite these risks, many patients benefit from a cardioversion because it can restore a regular heartbeat and reduce AFib symptoms. However, the cardioversion does not “cure” the atrial fibrillation. It merely restores normal rhythm in the moment, and does not change the heart’s tendency to go back into AFib. If the irregular heartbeats return, another cardioversion may be necessary. If it continues despite repeat cardioversions, medications used to maintain sinus rhythm (called antiarrhythmic drugs) may be administered, or a catheter ablation may be recommended to target areas of the heart contributing to AFib. To learn more about ablations, click here!
Figure 2: An example of a defibrillator used for cardioversions. Photo by StudentDoctorDG,
CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=122214646
References:
- “Cardioversion.” Ucsfhealth.Org, UCSF Health, 6 Aug. 2024, www.ucsfhealth.org/treatments/cardioversion.
- “Cardioversion: Procedure, Treatment & Recovery.” Cleveland Clinic, 30 June 2025, my.clevelandclinic.org/health/treatments/16952-electrical-cardioversion.
- “OHSU Knight Cardiovascular Institute.” OHSU, www.ohsu.edu/knight-cardiovascular-institute/arrhythmia-and-heart-rhythm-diagnosis-and-treatment. Accessed 12 Dec. 2025.
