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Synchronized cardioversion is a precisely timed introduction of electric current to the heart in order to restore a normal heart rhythm. Cardioversion essentially refers to converting the heart back to sinus rhythm, and synchronized refers to the way this procedure is timed during the heartbeat. There are other forms of cardioversion, such as using medications to restore normal heart rhythm. This treatment should also be differentiated from defibrillation, because it uses much less electricity.
Either pharmaceutical or synchronized cardioversion are the main treatments for conditions like atrial fibrillation or flutter. The advantage of using electricity is that it avoids the side effects of many anti-arrhythmia drugs. Also, a single procedure may be a quick treatment for certain arrythmias, although it may not have permanent results.
On the other hand, receiving an electric shock to the chest is painful. Most patients who have synchronized cardioversion need to be anesthetized during it to reduce pain. Not all heart patients are candidates for sedation. Additionally, those who undergo this procedure can be at risk for developing blood clots in the ventricles, so they often need to either use an anticoagulant for about a month prior to the procedure or have a transesophageal echocardiogram performed concurrently with it to look for the formation of blood clots, which if unaddressed, could cause heart attack or stroke.
These risks aside, this medical procedure has a long history of use and it has been refined with newer, more precise monitoring equipment. In many cases, an electrocardiogram (EKG) monitors the patient and is connected directly to the paddles that will deliver the shock. These devices signal the doctor, usually an electrophysiologist, performing the procedure as to exactly when to deliver the current. Continued monitoring of the EKG show whether sinus rhythm has been achieved.
Level of risk in undergoing synchronized cardioversion should be compared to outcome. Only about 20% of people continue to have normal sinus rhythm within a year of the procedure, and it’s not unusual for patients to need more than one electrical cardioversion. Patients may still require anti-arrhythmia drugs in order to prevent future arrythmias.
Some patients aren’t good candidates for this procedure. It tends to work less effectively if people have had long-standing problems with arrythmias, or if they have other heart issues like diseased valves or an enlarged heart. People with ventricular arrythmias may not respond well to synchronized cardioversion, either. Patients should discuss with an electrophysiologist their condition and options, to determine if this form of cardioversion or another treatment is the best choice.