What is it?
Cardioversion is a procedure used to return an abnormal heartbeat to a normal rhythm.
With electrical cardioversion, a high-energy shock is sent to the heart to reset a normal rhythm. It is different from chemical cardioversion, in which medicines are used to try to restore a normal rhythm.
Why is it done?
Normally, a special group of cells located in the right upper chamber begin the electrical signal to start the heartbeat. The signal quickly travels down the heart's conducting system on the way to the ventricles, the two lower chambers of the heart.
Various problems can disrupt this signaling pathway and lead to abnormal heart rhythms. The heart might beat very quickly, not leaving it enough time to fill with blood between beats. This can prevent the heart from pumping enough blood to the body. Some abnormal heart rhythms raise the risk of stroke. Some also raise the risk of life-threatening rhythms that can lead to sudden death.
Electrical cardioversion can help treat several different abnormal heart rhythms. It is commonly used to treat atrial fibrillation (AFib). With this condition, the atria of the heart quiver instead of beating the right way.
Electrical cardioversion is also useful for treating other abnormal heart rhythms, like atrial flutter, which is similar to AFib. It can also be used to treat certain kinds of supraventricular tachycardias and ventricular tachycardia (VT). These types of heart rhythms can cause heart rates that are too fast. This can prevent the heart from pumping enough blood.
How is it done?
Cardioversion is usually a scheduled outpatient procedure.
The patient typically needs to stop eating and drinking 6-8 hours before the scheduled procedure as anesthesia is given.
Clear instructions should be obtained regarding taking of medications, in particular heart rhythm medicines and blood thinners before the procedure. Stopping necessary medications before the procedure will likely lead to cancellation of the procedure.
Blood tests (particularly for blood thinning) may need to be done close to the procedure.
The physician will likely want a transesophageal echocardiography test before the procedure. This test is a special kind of ultrasound. A thin, flexible tube is put down the throat and into the esophagus. Here, the tube is close to the heart. It lets the doctor see if there are any blood clots in the heart. Cardioversion will be delayed if a clot is found.
Soft electrode pads are placed on the chest and maybe on the back. Some areas of skin may need to be shaved to get the electrode pads to stick.
These electrodes will connect to a cardioversion machine.
The anesthesiologist will give medication through the vein to provide brief general anesthesia for the procedure.
Using the cardioversion machine, a programmed high-energy shock is sent to the heart. This should convert the heart back to a normal rhythm.
The procedure takes only a few minutes.
Patient usually wakes up 5 to 10 minutes after the procedure and is then closely watched for a few hours for signs of complications.
Patient should have someone arranged to be driven home after the procedure.
Risks & Complications
Most patients have a successful electrical cardioversion, though occasionally it may be unsuccessful, and it does have certain risks.
Individual risks may vary based on age, the type of abnormal heart rhythm, and other medical conditions.
Some other risks are:
Other less dangerous abnormal rhythms
Temporary low blood pressure
Heart damage (usually temporary and without symptoms)
Dislodged blood clot, which can cause stroke, pulmonary embolism, or other problems