Advice after your nerve block for surgery
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Introduction
Your doctor has requested that you be admitted to the hospital for a procedure called a cardioversion. You may be feeling anxious and unsure about what is going to happen.
This leaflet is aimed at trying to reduce some of that anxiety and to inform you about cardioversion.
Why do I need a cardioversion?
Your heart has an abnormal or irregular rhythm. In many patients, it does not give rise to symptoms, but in others, it can cause breathlessness, fatigue or chest discomfort and a feeling of palpitations.
Cardioversion is a treatment that can be successful in treating these abnormal heartbeats.
What should I expect?
Prior to the cardioversion, you will have a pre- assessment, where a nurse will explain the procedure and ensure that you understand what will occur on the day you come in. You will already be taking anticoagulation drugs such as Warfarin or DOAC, to prevent formation of a blood clot. It is important that your INR (clotting level) is measured regularly for several weeks prior to the cardioversion, and you should see your anticoagulation nurse or GP who will arrange regular WEEKLY blood tests to monitor this. If you are on a DOAC, you must be compliant with taking this and must have no interruption for at least 30 days or your procedure may be deferred.
The cardioversion will be done as a day case, which means you should be ready to go home in the afternoon. You will not be able to drive for 24 hours and should have a responsible adult with you overnight. If you should have any problems with this, please discuss it with the pre-assessment nurse. You should not eat or have milky drinks from midnight but can have clear fluids up to 2 hours prior to the admission. If you are a diabetic, you will be given guidelines at your pre-assessment appointment to follow before and after the procedure.
The procedure
On the day of your cardioversion, you will have bloods taken and an ECG. Occasionally the procedure may have to be cancelled due to these results - you may have reverted to a normal rhythm, or your blood results may be abnormal, and it would be unsafe to carry out the procedure on the planned day.
Unfortunately, we are not able to assess this until the day of the cardioversion, as blood tests and heart rhythm can change daily, and we therefore apologise for any inconvenience this may cause.
The treatment involves having a short anaesthetic (about 5 minutes) so you will be asleep. The nurse applies a direct electrical current shock to the chest wall via pads, which is designed to reset the heart to a normal rhythm.
Risks of the procedure
The risks of this procedure are low; however, you must be aware of any risks that could potentially occur. Because the heart rhythm is irregular, the upper chambers of the heart are not able to contract vigorously. There is, therefore, a possibility that a blood clot can form in the heart chamber. Restoration of a normal rhythm by cardioversion can dislodge a blood clot from the heart and cause a heart attack or stroke. Fortunately, thinning the blood before cardioversion can prevent most blood clots. This can be done with tablets such as Warfarin or DOACs. Before performing a cardioversion, your doctor will ensure that your blood has been adequately thinned, and the risk of clot formation is low.
There is a small risk that other abnormal rhythms may occur which may need correction with other drugs, but facilities are readily available. Also, there is a risk of skin burns (like sunburn) occurring where the pads are placed on the chest. This may be slightly uncomfortable and may be relieved with Paracetamol. The procedure is carried out under anaesthesia. An anaesthetic leaflet is enclosed. Your doctor would not recommend the procedure unless it is felt that the benefit outweighs the risk.
Occasionally, more than one electric shock is required before the heart reverts to a normal rhythm. However, the cardioversion may not always be successful in reverting the heart rhythm, in which case your doctor may wish to try alternative medications.
Following the cardioversion
You will remain attached to a cardiac monitor for a short time following the procedure, and your blood pressure and heart rate will be recorded. Once you are fully awake, you will be given a drink and a sandwich and allowed to sit out in a chair.
A cardiac nurse will assess you prior to discharge, and you will be given appropriate information, appointments and medication.
Please remember - you will not be allowed to drive for 24 hours and should have a responsible adult with you overnight.
Contact us
If you have any queries relating to this information, please contact the Cardiology service.
About this information
Service:
Cardiology
Reference:
C/016
Approval date:
7 August 2025
Review date:
1 August 2028
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Important note
This page provides general information only. It is developed by clinical staff and is reviewed regularly every 3 years for accuracy. For personal advice about your health, or if you have any concerns, please speak to your doctor.