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This is a very important document. Please read and discuss this with relatives if necessary.
What is an Electrical Cardioversion?
Direct Current Cardioversion (DCCV) is a procedure for treating abnormal heart rhythms such as Atrial Fibrillation (AF) or Atrial Flutter (Afl). The aim is to restore the heart’s normal regular rhythm by delivering a controlled electric shock to the heart. However this is NOT a permanent cure for AF or AFl. AF and AFl often recur after DCCV. The procedure only takes a few minutes and is carried out while you are asleep, under a deep sedation. A doctor or specially trained nurse will carry out the procedure in the presence of an anaesthetist.
What are the benefits of Cardioversion?
In AF or Afl the upper chambers of the heart quiver rather than pump and thus do not clear the blood out effectively. This can cause small blood clots to form inside the chambers, which increases the risk of having a stroke. AF and Afl gives rise to a sensation of heart racing and this can make you breathless and fatigued. AF and Afl may suddenly terminate with a pause in the heart beat that may make you lightheaded for seconds.
DCCV may restore normal heart rhythm. If it does, the symptoms may be relieved. If symptoms are relieved, the doctor may consider referring you for a procedure called ablation for permanent cure of AF or Afl. If symptoms are not relieved despite a normal heart rhythm, AF or Afl is not the cause of the symptoms and therefore, curing the AF or Afl will not improve your symptoms.
The potential benefits of restoring normal heart rhythm include:
• Relief from the physical symptoms
• Improvement in exercise capacity
• Improvement in the hearts pumping efficiency
Restoring normal heart rhythm with DCCV will not achieve:
• A permanent cure for AF or AFl.
• Remove the need for blood thinners (anticoagulants).
• Remove the need for medications for heart rhythm control.
Once you and the doctor have decided that DCCV is needed, you will be given the following documents:
• This Patient Information Booklet for you to take home.
• Direct Oral Anti-coagulation (DOAC) OR Warfarin Monitoring Sheet for you to take home.
Preparation before the procedure is very important (please read in full)
Preparation for cardioversion includes taking anti-coagulation (blood thinning) medication such as Warfarin OR a ‘DOAC’ (Edoxaban, Apixaban, Rivaroxaban, Dabigatran). If you are not already taking anti-coagulation medication you will be prescribed a DOAC, unless there is a contraindication. If you are already taking warfarin for anything else other than a mechanical prosthetic
valve e.g. AF/AFl, clot on the lung, clot in the leg etc., the warfarin will be replaced by a DOAC and you will be given a prescription for it. If there is contraindication to a DOAC you will be continued on warfarin. If you are already taking warfarin for a mechanical prosthetic valve you will continue with the warfarin.
DOAC (no blood tests needed for monitoring its effect):
• You must take DOACs as prescribed without ANY missed doses for 4 consecutive weeks before and 6 weeks after DCCV.
• You will need to date and sign the Direct Oral Anti-Coagulation Monitoring Sheet provided every time you take the DOAC to confirm that every dose has been taken.
• DCCV will have to be cancelled if you have missed any doses because of the increased risk of a stroke
• You MUST bring the Direct Oral Anti-Coagulation Monitoring Sheet with you when you come for the DCCV. DCCV will not be done without it.
• It is essential that the blood clotting is at the right level for at least four weeks before and on the day of the procedure. This is to reduce the risk of blood clots dislodging and causing a stroke at the time of the cardioversion. Blood clotting is measured with a test called International Normalised Ratio (INR).
• You will need to have a weekly blood test to monitor your INR. Most patients taking Warfarin for AF/Afl will keep their INR between 2.0 – 3.0 but it is worth noting that for DCCV procedure we can safely accept results between 2.0 and 4.0. If you have mechanical prosthetic valve, maintaining your usual INR range would be adequate.
• DCCV will have to be cancelled if you have INR readings outside of the required range or if you don’t have weekly INR readings because of the increased risk of a stroke.
• Digoxin – If you are taking Digoxin tablets, please stop taking these 72 hours before the procedure.
• Beta-blockers (Bisoprolol, Atenolol, Carvedilol, Nebivolol, Metoprolol, Propranolol etc.) If you are taking Beta-blocker tablets, please do not take them on the morning of the procedure.
• Anti-diabetic medications – If you are on insulin take half of the morning dose on the day of the procedure. Do not take any anti-diabetes tablets on the morning of the procedure.
Take all other medicines as prescribed.
The day before the Cardioversion
You will need to attend Cardiology Out-patient department between 8-10 a.m on the day before the DCCV (a Wednesday) to have a blood test in preparation for the procedure. It is essential that you attend as the procedure cannot be done without these blood results.
The day of the Cardioversion
You must not eat or drink anything after midnight on the day, although you may have a small amount of water with your morning medication. Please bring your regular medications with you.
Please bring a dressing gown and slippers with you. You may want to bring a pair of shorts or comfortable trousers/skirt to wear. You will be asked to wear a hospital gown for the procedure.
A Doctor will see you to make sure you understand the procedure before asking you to sign a consent form. If you have any questions, this is the time to ask. The anaesthetist will see you and discuss the sedation.
During the Procedure
We will connect you to a cardiac monitor and position two sticky pads (defibrillator pads), one on your chest and one on your back. These are connected to a defibrillator machine. A cannula (fine tube) will be inserted in a vein in your hand. This is used to deliver the sedation. You will then be asleep for 5-10 minutes. While you are asleep a controlled shock will be delivered to your heart. This should restore your hearts’ normal, regular rhythm.
Risks and Complications
Complications from cardioversion are rare. A common complication is transient skin redness at the site of the shock. In most cases this can be relieved with after-sun or aloe vera cream. You will be given advice if this is necessary. Serious complications are very rare. Provided anti-coagulation (blood-thinning) medications have been taken appropriately in the period leading up to the procedure, the risk of stroke occurring at the time of the procedure is less than 0.5% (1 in 200). Immediate success (the return of normal, regular rhythm) is achieved in more than 90% of patients, however the irregular heart rhythm may return. In a few people this happens within hours or days of the cardioversion, in others it may be weeks or months. After 12 months around 50-70% of people will remain in a normal heart rhythm.
After the Cardioversion
Once fully awake you can eat or drink. We will provide light refreshment. We will monitor your heart rate and blood pressure until we are satisfied that you are fit for discharge. You should be discharged 3 hours after the procedure. We will discuss the results of the procedure with you and advise if any of your medicines need to change. We will write to you GP informing him/her about the results of the procedure and any changes to medications that you may need. You will need to continue DOAC or Warfarin.
For your own safety you must have a relative or friend to collect you and stay with you overnight. Due to the sedation, you will not be able to drive, operate machinery or sign legal documents for 48 hrs. A follow up appointment will be made for you with the doctor who referred you for the procedure. During that appointment, an ECG will be performed to assess whether you have reverted back to AF/Afl and whether your symptoms had improved when you were in normal regular rhythm. The Doctor will review your medications including the need for continued DOAC or Warfarin.
What to do if you feel unwell
If you have any chest pain or you are having difficulty breathing when you go home, please call an ambulance immediately and remember to inform them of your recent procedure.