This page is for patients and their families when preparing for a cardioversion.
What is a cardioversion and how is it done?
Cardioversion is done in hospital under a short general anaesthetic (you will be asleep) to treat an abnormal heart rhythm.
The doctor will place electrode ‘sticky pads’ on the front and back of your chest and send electrical energy through the chest to the heart. This energy is synchronised (works at the same time) with your own heartbeat and should return your heart to the normal regular rhythm.
Cardioversion is usually done as a day case, so that you come to hospital and go home the same day. Occasionally it is necessary to stay overnight.
Why do I need to have a cardioversion?
You may have been having palpitations or an irregular heart beat for some time. Your doctor may have prescribed a course of tablets such as amiodarone, digoxin, bisoprolol, or diltiazem to control your heart rhythm. These are not always successful and if you are troubled by palpitations, breathlessness, chest discomfort, or reduced activity then cardioversion may help. By restoring your heart’s normal regular rhythm (sinus rhythm) your symptoms can improve.
Will it be successful?
The cardioversion is more likely to be successful if your heart has been in an abnormal rhythm for only a short while, like a few months. The effectiveness varies, but in 9 out of 10 people the cardioversion will restore the normal regular rhythm.
However, some of these people will go back to how it was in the next few days or weeks. In a few cases the procedure will not be successful at all.
For 5-6 people out of 10 who have cardioversion, their heart will likely still be in the normal regular sinus rhythm 12 months later.
The best results are seen in patients with normal heart structures seen on an echo scan. Patients with structural heart impairment, for example leaky valves or enlarged heart chambers, have a lower chance of long-term success.
Before you come into hospital
Your doctor will prescribe a blood thinning medication called oral anticoagulant, for example apixaban or dabigatran. These are taken twice a day for 4-6 weeks before the cardioversion and you will continue taking them afterwards. It is important that you don’t miss doses of the anticoagulant as this can increase the slight chance of having a stroke following the cardioversion.
You will be seen by a cardiology pre-op assessment nurse, before your procedure date. Usually, the procedure is done as a day case procedure (home on the same day).
The nurse will talk to you, take a blood sample, do an ECG recording, and check that that you can get to the hospital, and someone can take you home. You will not be able to drive yourself home.
Important information
- You must not eat or drink for at least six hours before your admission to prepare for the general anaesthetic.
- Take your regular medications as usual, early on the morning of your cardioversion with a small sip of water.
- If you are taking digoxin, you should stop taking it 48 hours before you come to hospital.
- If you are diabetic, the pre-assessment nurse will explain what you need to do before you come into hospital.
When you arrive at hospital
You will be seen by a nurse and a doctor who will talk about the procedure and answer any questions you have. You will then be asked to sign a consent form to show that you are happy to have the treatment.
The anaesthetist will talk to you about what will happen and ask you about your health and any allergies you may have.
You will be attached to a cardiac monitor to record your heart rate. Staff will take your blood pressure and record your breathing rate.
The anaesthetic will be given through a small needle in the back of your hand and as you drift off to sleep the electrical cardioversion will be done. The procedure takes about 5 minutes. You will then be taken to the recovery area.
What happens next?
You will sleep off the effects of the anaesthetic and wake up in your own time. When you wake up you will probably be lying on your side and wearing an oxygen mask. The nursing staff will monitor your blood pressure, heart rate, and breathing rate.
When you are fully awake you will be told how the procedure went and staff will be happy to answer any questions. Some people feel slightly sick after anaesthetic, but you will be given a drink and something to eat when you feel able to.
When you have recovered, you will have another ECG done to see if the procedure has been successful.
As long as you feel well enough, you will be able to be collected and go home 2-4 hours after your treatment.
Even if the treatment has been successful, the doctor may tell you to continue taking some or all of your tablets for a while longer.
An outpatient appointment will be arranged for you to see your hospital doctor who recommended the cardioversion and you can ask about your medicines then.
Please remember it takes a while to recover from a general anaesthetic.
For 24 hours after cardioversion:
- You must not drive.
- You must not operate any potentially dangerous devices as your reflexes may be reduced.
- You must not make any important decisions or sign any legal documents.
- Do not drink alcohol.
- Do not boil a kettle or use anything that involves heat.
- When rising up to sitting or standing, do it slowly as you may feel dizzy if you get up too quickly
- We advise you to rest for the remainder of the day after your treatment and to take the next day off work.
What risks are there?
Cardioversion is a safe procedure which has been done in most hospitals in the UK for many years.
Complications are rare, but there are risks that you need to think about before you sign the consent form.
These risks are higher in patients who are very unwell or have certain medical conditions. You need to weigh up the risks of having the procedure or leaving the condition untreated, against the potential benefit of the procedure.
Below are approximate complication rates for patients having cardioversion. However, you need to remember that these numbers include all patients, regardless of how ill they were to start with.
- Risk of an anaesthetic problem or death is one in every 100,000 patients.
- Risk of having a stroke or another type of blood clot problem is approximately one in every 1000 patients.
- There is a minor risk of slight burns to the chest from the paddles or adhesive pads used during the procedure.
- Rarely, some patients may require a temporary pacing wire to be inserted if the heart beats too slowly.
- Rarely the procedure causes a more serious, life threatening abnormal heartbeat. This is so uncommon that there are no available statistics.
References and further information
© North Bristol NHS Trust. This edition published December 2024. Review due December 2027. NBT002341
