How can a normal heart rhythm be restored?

Photo of man taking medication (PantherMedia / Wavebreakmedia ltd)

People with atrial fibrillation can have treatment to restore a normal heart rhythm, either through medication or weak electric shocks. The medical term for this kind of treatment is cardioversion. If the normal heart rhythm can’t be stabilized with medication afterwards, a treatment known as catheter ablation may be considered.

In atrial fibrillation, there is a problem with some of the signals that set the pace of the heart. This typically leads to a fast and irregular heartbeat, which can cause symptoms such as palpitations, shortness of breath and exhaustion.

Treatment with medication (pharmacological cardioversion) or controlled electric shocks (electrical cardioversion) can often restore a normal heart rhythm. Afterwards, medication is typically used in order to try to prevent the heart rhythm from becoming irregular again. Even if a normal heart rhythm (sinus rhythm) can be successfully restored through cardioversion, people still sometimes have to take medication to lower their pulse.

How can the sinus rhythm be restored?

Cardioversion can be attempted using medication at first – particularly if it is the first time that atrial fibrillation has occurred. The medications used for this purpose are known as anti-arrhythmics (medication for heart rhythm problems). They are either injected directly into a vein or taken in the form of tablets.

The likelihood of pharmacological cardioversion being successful will depend on various factors, such as whether the person has any accompanying medical conditions and how long they have had atrial fibrillation for. It works in about 50 to 70 out of 100 people on average.

The possible side effects include low blood pressure and a slow heart beat, which may be felt as temporary dizziness, for example.

Electrical cardioversion

In most cases, cardioversion is done using electric shocks rather than medication. This involves placing electrodes on the upper body. These release a weak electric signal to help make the heart beat more regularly. The procedure is carried out using an anesthetic lasting just a few minutes. Electrical cardioversion works in about 90 out of 100 people, and is often even successful in people who have had atrial fibrillation for a longer amount of time. The risks include anesthetic-related complications and mild skin burns. Also, any blood clots in the atria (upper heart chambers) may become dislodged and enter the bloodstream.

Preventing complications caused by cardioversion

The largest risk associated with cardioversion is the risk of a blood clot in the heart breaking free and causing a stroke. To try to reduce this risk, a special ultrasound scan is done beforehand to see whether there is a blood clot in the heart. In this procedure, known as a transesophageal echocardiogram, a thin probe is passed into the person’s esophagus (food pipe) and positioned behind their heart. Sometimes it isn’t absolutely clear whether there’s a blood clot there, or sometimes this kind of ultrasound isn’t carried out. In that case, the person takes anticoagulants for at least three weeks before cardioversion in order to dissolve any blood clots that might be there.

But it still isn’t possible to completely avoid the risks associated with cardioversion: Estimates based on studies have shown that about 1 out of 100 people have a stroke following cardioversion, despite the preventive measures.

Anticoagulants are also recommended in the four weeks after cardioversion – if the person isn’t already taking them anyway.

What is catheter ablation and when is it considered?

Catheter ablation involves inserting a thin tube (catheter) into a vein in the groin, and moving it along the vein until it reaches the left atrium of the heart. To do this, the catheter has to puncture the wall of the heart. The tip of the catheter is then heated up using a high-frequency electrical current, and the heat is used to destroy various areas of tissue on the inner wall of the heart that may be causing the atrial fibrillation. This treatment approach is known as radiofrequency ablation (RFA). Alternatively, extreme cold can be used to destroy the tissue by freezing it rather than burning it with electricity. This approach is known as cryoablation.

Catheter ablation is usually only considered as a treatment option if someone still has bothersome symptoms despite treatment with medication. Various risks are associated with catheter ablation: Damage to the heart, lungs or food pipe might occur during the procedure. Although this kind of complication is rare, it can be life-threatening and may require emergency treatment. The most common side effect is bruising in the groin area, at the site where the catheter was inserted.

Studies have found that catheter ablation can often stabilize the normal (sinus) heart rhythm if previous treatment with medication wasn’t successful. But there is no guarantee that the heart rhythm will stay normal: About 25 out of 100 patients in studies needed a second catheter ablation procedure after a while because they developed atrial fibrillation again.

What’s more, many questions surrounding this treatment still haven’t been answered: In particular, it still isn’t clear whether catheter ablation lowers the risk of a stroke or heart failure (cardiac insufficiency). There also hasn’t been enough research to say how well catheter ablation relieves the symptoms of atrial fibrillation. Some people still have these symptoms despite having a normal heart rhythm. Additional treatment with anti-arrhythmics may then be considered.