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Having a VF Induction
This information explains the benefits and risks of the procedure as well as what you can expect when you come to the hospital., it will also answer some of the questions you may have about having a VF induction.
What is VF Induction?
A VF induction tests your Implantable Cardioverter Defibrillator (ICD) is working correctly.
An ICD is an electronic device that constantly monitors your heart rhythm. When it detects a very fast, abnormal heart rhythm (ventricular fibrillation) it delivers energy to the heart muscle. This causes the heart to beat in a normal rhythm again. If the heart’s rhythm is not corrected your heart could stop.
During a VF induction we will put your heart into ventricular fibrillation and then wait for the ICD to work. If it does not correct the VF heart rhythm an external defibrillator will do the job of the ICD and deliver a shock.
What are the benefits of having a VF Induction?
A VF induction is performed to check that the ICD is working. If it is not working correctly, the cardiac physiologist will change the settings on your ICD, usually whilst you are in hospital.
What are the risks?
If the ICD does not recognise and shock the dangerous heart rhythm then an external defibrillator will be used to shock your heart. This may cause minor discomfort to the chest as you recover from the procedure. If you have skin irritation after the procedure, a cold damp flannel will help reduce the inflammation.
If you have atrial fibrillation there is a risk that when you have the shock, if there was a clot in your heart it may be dislodged and move. This could possibly block a blood vessel elsewhere (normally in the head) and could result in a stroke.
If you have atrial fibrillation your medical team will prescribe warfarin or one of the new anticoagulants to help reduce the risk of clot formation and stroke.
The importance of taking your medications as prescribed prior to your procedure
If you are on warfarin your INR must be above 2.0 for at least 4 consecutive weeks. This is why the VF induction is not performed at the time of the device implantation.
Your INR must be checked each week for the four weeks prior to your admission to ensure it is safe to perform the procedure.
If your INR has not been above 2.0 every week for the four weeks prior to your procedure you will not be able to proceed with the VF induction as there is a chance you could have a clot in your heart.
If you are on one of the newer anticoagulants, you must confirm that you have been compliant with your medication regime for more than 30 days with no missed doses for the procedure to proceed.
Are there alternatives?
When you have your pacing chekc the cardiac physiologist will check the pacing function of your ICD. This is done remotely by placing a small device over the device for a few minutes, this will check that the pacing setting are correct, but can not check that the device will provide a shock if your heart goes into VF.
A VF induction is the only way to check this.
How can I prepare for a VF Induction?
You must take your medications as prescribed by the medical team, and it is important that you follow the advice given by the medical team and when you have your pre-assessment appointment.
You should not eat or have milky drinks from midnight the night before you come in for your procedure. You can have clear fluids up to 2 hours prior to being admitted. You should take your medications at this time. If you are a diabetic you will be given guidelines at your pre-assessment appointment to follow before and after the procedure.
Please do not bring any valuables to the hospital, there may be times when your belongings are unattended.
Please bring:
- All your medications (in their original packaging)
- Your yellow anticoagulation book/blue slip
- The telephone number for your next of kin
- Reading glasses and if you are hard of hearing, your hearing aid.
- A book or newspaper as there will be time waiting before and after your procedure.
You can arrive on your own, or a relative may come in with you, they can stay with you to make sure you are settled but will have to leave once you are in the department. They will need to return when you are ready to be collected. You must be collected after the procedure and will need supervision form a responsible adult when you get home.
You will be involved in all decisions about your care and treatment. Once you have confirmed you are happy to have the procedure you will be asked to sign a consent form. This confirms that you agree to have the procedure, understand what it involves and have discussed the risks of having the procedure.
What happens during a VF Induction?
On arrival to the department, we will review the readings in your anticoagulation book to ensure that your INR has been above 2.0 for the last four consecutive weeks.
You will have blood samples taken to check your INR and potassium levels. We check your potassium levels in addition to your INR as if your potassium is not within normal range your heart rhythm can be affected.
An electrocardiogram (ECG) is taken to check the rate and rhythm of your heart.
When the results of the blood samples are back, they will be reviewed by a doctor. The procedure will take place in the Cardiac Catheter Labs, you will be escorted to the procedure room by a nurse.
When you are ready, a nurse will escort you into the Cardiac Interventional Suite.
Inside the procedure room you will have a small device placed on your chest, over the area where the ICD was inserted to check your pacing settings.
You will have monitoring stickers applied, and larger stickers which are attached to an external defibrillator. We will also monitor your blood pressure and oxygen saturations.
Once ready to proceed you will heavily sedated so that you are asleep. The ICD will be programmed to irritate the heart muscle so that it goes into VF (a dangerous heart rhythm).
The ICD should recognise the abnormal heart rhythm and shock the heart so that your normal rhythm returns. The medical team will monitor you throughout to ensure the ICD has recognised VF and has appropriately appropriately by shocking the heart. If there was an issue with the ICD delivering a shock as required an external shock would be delivered via the large stickers and the external defibrillator.
Will I feel any pain?
You will be asleep for the procedure itself. As mentioned before if the ICD does not work properly the sticky pads will deliver a shock from the external defibrillator. This may cause aching to the chest, and can cause skin irritation. This can be soothed with a cold damp flannel or some mild pain relief like paracetamol. Any marks from the sticky pads will fade after a few days. If you have pain after the procedure let the nursing team know so they can get pain relief for you.
What happens after the procedure?
After your procedure you are monitored in bed until you have fully woken up and are feeling well, you will be kept in bed until then as you may be unsteady after being sedated for the procedure. You can eat and drink once you are are awake enough.
Once you have recovered from the anaesthetic, you can get out of bed and start walking around the ward. Once you have been up for an hour or two you can go home, all being well.
What do I need to do after I go home?
Rest when you get home, and take things easy for the next two days, in particular do not do any heavy lifting or excessive exercise.
Driving after the procedure
Instructions on driving depend on why your ICD was initially implanted and what you have already been told regarding driving. If you can drive, REFRAIN FROM DRIVING FOR 24-48 HOURS post VF induction.
If you have been told you cannot drive at all, then you still cannot drive, this will apply for the full time period you were told not to drive for.
Will I have follow up?
If the ICD worked correctly during the VF induction you will have a routine pacing check 6 months after the ICD was inserted.
If the ICD did not work correctly we will normally keep you in hospital until the issue has been rectified.
Who can I contact for further information?
If you have any questions or concerns about having a VF induction, please contact:
Cardiac Arrhythmia Nursing Team: 03006 132641
Frimley Park Hospital Clinical Investigations 03006 133300
Wexham Park Hospital Clinical Investigations 03006 154685
If you feel unwell after the procedure, please contact your GP.
Useful websites
Contact us
If you have any queries relating to this information, please contact the Cardiology service.
About this information
Service:
Cardiology
Reference:
C/037
Approval date:
19 January 2026
Review date:
1 January 2029
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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.