Cardiology - A guide to your Cardioversion

What is Cardioversion?

Cardioversion is a procedure for treating abnormal heart rhythms such as atrial fibrillation and atrial flutter. The aim is to convert the heart to a normal rhythm by delivering a controlled electric shock to the heart. The procedure is carried out under general anaesthetic as a day case procedure.

Why am I having this procedure?

Some people are unaware of their abnormal heart rhythm, whilst others experience symptoms such as extreme fatigue, shortness of breath, palpitations and a lack of exercise tolerance. There is also a small chance of having a stroke.

When the heart beats irregularly, the upper parts of the heart do not contract and pump out the blood properly. This can result in not enough blood leaving the heart, which causes the above symptoms.

It can also cause small blood clots to occur in the chambers, which could lead to a stroke. Taking anticoagulation reduces this risk.

Are there any risks involved?

Complications from a cardioversion are rare. A common complication is temporary skin redness over the chest area at the site of the electric shock. This can be relieved by applying a cream if necessary. The risk of having a stroke is under 1% (1 in 100).

How successful is the procedure?

Immediate success (the return of a normal, regular heart rhythm) is achieved in more than 90% of patients having cardioversion.
However, the abnormal heart rhythm might return. In a few people this happens within hours or days of the cardioversion; in others it happens weeks or months later. After 12 months 50-70% of patients will still have a normal heart rhythm.

Your doctor will only recommend this treatment if they feel that the benefits outweigh these small risks.

Are there any alternatives?

Atrial fibrillation ablation

An alternative treatment is to ablate the arrhythmia using a steerable catheter placed into the heart through a vein. The tip of the catheter is either heated or cooled to produce controlled burns to the inner surface of the heart in order to prevent atrial fibrillation occurring.

This is a rapidly developing technique which is recommended when standard treatment such as medication and cardioversion have not been successful.

It is not recommended as a first-line treatment for atrial fibrillation at present.

Preparation for the procedure

You will be prescribed a drug to thin the blood in the weeks prior to the cardioversion to reduce the risk of blood clots. Your blood needs to be adequately thinned for at least 3 weeks prior to cardioversion. You may attend the anticoagulation clinic regularly. Once your blood is thin enough we will list you for cardioversion.

If you are on Digoxin you will be asked to stop this 2 days before cardioversion.

You will have a final set of blood tests and a heart tracing (ECG) in the days prior to your cardioversion.

This is a day case procedure. You will need someone at home to look after you overnight.

Admission to hospital

You will be asked to attend the Day Surgery Unit (Red Area) at 12 o’clock on the day of your cardioversion.

Do not have anything to eat after 7.30am, and then water only up until 11.30am.

Patients with diabetes

If you have diabetes and are on the afternoon list, you should have breakfast and take your tablets for diabetes as normal. If you are on Insulin, you should take only 1/2 your normal dose with breakfast.

DO NOT HAVE LUNCH AND DO NOT TAKE ANY DIABETIC TABLETS OR INSULIN AT LUNCH TIME.

Please bring your anticoagulation booklet and any medications that you are prescribed with you.

Please also bring a dressing gown and slippers (we will give you a theatre gown for the procedure).

You will be seen by a member of the cardiology team to ensure that you understand the procedure.

The Cardioversion procedure

You will be taken to theatre on your bed. We will monitor your heart and give you oxygen to breath. We will also place pads on your chest and back (defibrillation pads).

The anaesthetist will then place a fine tube into the back of your hand and administer the anaesthetic. Once you are asleep we will give a controlled shock to your heart. You will not feel anything.

After the procedure

You will wake up 5-10 minutes after the procedure, initially in a recovery area. Once you are fully awake you will be transferred back to the Day Surgery Unit where you will be monitored for two hours. You will be offered something to eat and drink.

You will be ready to go home 3-4 hours after the procedure. The anaesthetic can make you feel tired, clumsy or forgetful for about 24 hours. You should not drive, operate machinery or make important decisions for 48 hours.

You will be given advice regarding any changes to your medication before you go home.

Even if the cardioversion is successful, it is very important that you continue your anticoagulation until advised otherwise.

Prior to your procedure if you have any questions then please consult our advanced nurse practitioner on 0161 206 8310 Monday to Thursday 9am - 5pm.

Further information is available from:

The British Heart Foundation, Greater London House, 180 Hampstead Road, London NW1 7AW
www.bhf.org.uk or telephone 020 7554 0000