What Is It?
Electrical cardioversion (CV) is a procedure where a patient with a rhythm abnormality undergoes sedation and receives an electrical shock to the chest meant to convert the heart back to normal rhythm. In certain individuals CV is accompanied by a transesophageal echocardiogram (TEE) for visual assessment of the heart prior to the procedure.
How is it done?
You will start by discussing the nature of the procedure with your cardiologist along with the risks and alternatives. On the day of the CV you'll come to the hospital where baseline blood testing will be done to verify that your electrolytes and blood counts are stable. You'll be prepped for conscious sedation and have electrical pads placed on your chest and back. As noted above, some patients will need to undergo TEE along with the CV, but both procedures will be done during the brief time you are sedated (please refer to the linked information on TEE). You will then be briefly sedated and your cardiologist will deliver a shock to your chest. With adequate sedation the procedure is painless. This very quick series of events takes no more than a few minutes. Your doctor will know immediately if the CV has been successful and will arrange for an electrocardiogram to confirm the presence of a normal rhythm. If the CV is not successful with one shock your doctor may deliver one or more successive shocks in short order.
What are the indications for the procedure?
Elective CV is most commonly recommended for the atrial rhythm abnormalities atrial fibrillation (AF) and atrial flutter. If you suffer from persistence of either rhythm and have associated symptoms (such as shortness of breath, lightheadedness, fatigue, palpitations, or exertional intolerance) you may benefit from CV as a means of returning your heart to normal rhythm. We sometimes recommend CV as an isolated therapy or in conjunction with the use of medications meant to stabilize cardiac rhythm.
How do you prepare for the procedure?
Your doctor will give you detailed instructions, but in general all you need to do is arrive at the hospital fasting for at least 12 hours. You will likely be instructed to take all your usual medications on the morning of the CV. Male patients should expect to have their chest and/or back shaved as part of the preparation (in order to improve electrical contact between the pads and the skin).
What are the risks of the procedure?
Despite the seemingly dramatic outward appearance of CV it is actually one of the least risky procedures that cardiologists perform. The greatest risk you'll face has to do with the conscious sedation, but risk is no different from that seen with typical sedation for other procedures. The shock itself can theoretically trigger a more dangerous rhythm abnormality but this is exceedingly uncommon and easily treated. Because stroke can rarely accompany conversion of AF to normal rhythm you'll either need to be on the blood thinner warfarin (Coumadin) or undergo TEE to exclude the presence of clot in the left atrium of the heart. The most common adverse outcome of CV is that it simply doesn't work. Your doctor should be able to give you some idea prior to the procedure what chance of success you might have and what options exist if your heart continues in AF despite CV.