Intervention that can be performed on an outpatient basis, electrical cardioversion helps restore a normal heart rate in people who suffer from certain arrhythmias. How does this act take place and what are its limits?

Electrical cardioversion (CVE) is a simple medical procedure that restores a normal heart rhythm in people who have an abnormal rhythm (arrhythmia) that persists despite optimal drug therapy. It is also called the use of “direct current” or “DC current” for electrical cardioversion. Electrical cardioversion is similar to defibrillation, but it uses less electricity.

Emergency

Electrical cardioversion is an absolute life-saving emergency in order to put an end to unsupported ventricular fibrillation or ventricular tachycardia that causes cardiac arrest. Survival and the consequences of such cardiac arrest depend on how quickly cardioversion is performed. In public places, in hospitals, as well as in emergency units (firefighters, ambulance services, etc.), semi-automatic defibrillators (DSA) make it possible to reduce delays.

Outside of the emergency

It is then a question of treating a crisis to put an end to it. The decision to achieve such an electric shock is up to everyone.

Most electrical cardioversions are aimed at people with pain:

• Persistent atrial fibrillation. Atrial fibrillation does not threaten the life of the patient, but it can interfere with the pumping efficiency of the heart and cause irregular or too fast beats;
• Rhythm disturbances in the upper chambers (atria) of the heart. 

Electrical cardioversion is performed in a hospital environment. This is a pre-planned procedure. The treatment is carried out on an outpatient basis and the person must be fasting and not allowed to drive after the examination.

Here are the steps:

• A nurse will place several large patches called electrodes on the patient’s rib cage or one on the chest and one on the back. The electrodes will be connected to a cardioversion device (defibrillator) using wires. The defibrillator will record the heartbeat throughout the procedure;
• A predetermined amount of energy or electrical impulse is carried by the electrodes through the body, to the heart;
• Before the shock is delivered, a brief general anesthesia is performed so that you do not feel the pain that the blow causes on the skin of the chest;
• This discharge of energy makes the heart jump, interrupts atrial fibrillation, and restores normal heart rhythm.

The repetition of electric shocks in the same person is quite possible and does not pose any particular risk. On the other hand, resorting to multiple shocks may be a sign that outpatient care is not sufficient and that other measures are needed to avoid them.

For most people, electrical cardioversion is the fastest and most effective way to:

• To treat the symptoms associated with the arrhythmia (palpitations at rest or on exertion, shortness of breath on exertion, or even heart failure or angina). This return to a sinus rhythm is not an “obligation” insofar as the cardioversion is only intended to relieve these symptoms;
• To restore a regular heart rhythm;
• To stop any sustained arrhythmia. 

The success rate is lower if the arrhythmia is old. Regardless of the effectiveness of the shock achieved, it is possible to repeat the procedure because electrical cardioversion only restores the normal rhythm and has no preventive role in relation to possible recurrences. This is why a complementary antiarrhythmic drug treatment is generally necessary and ensures as much as possible this role of preventing recurrence. 

Radiofrequency or cryotherapy ablation may be considered, but will be discussed depending on the person and their cardiac pathology.

Thus, the duration of stability of the normal rhythm which results from it depends on each one, according to the risks of recurrence.

Complications from electrical cardioversion are rare and doctors can take steps to reduce them.

Dislodged blood clots

Electrical cardioversion can cause blood clots to form in other parts of the body and this can lead to life-threatening problems. In order to prevent this complication, anticoagulant therapy is prescribed 3 weeks before the procedure and an echocardiography check may also be performed. If this anticoagulation was not satisfactory, the procedure could be postponed.

Abnormal heart beat

During or after the procedure, some people cause other problems with the heart rhythm. It is a rare complication that, if it occurs, usually does not appear until a few minutes after electrical cardioversion. To correct the problem, your doctor may give you additional medication or shocks.     

Skin burns

Where the electrodes have been placed, some people may have minor skin burns. Pregnant women can have cardioversion. It is only recommended to monitor the baby’s heart rate during the procedure.