An implantable cardioverter defibrillator (ICD) (also known as automatic implantable cardioverter defibrillator (AICD) is an electronic device implanted just under the skin of the upper chest, similar to a pacemaker. It is about the size of a pager and performs several functions.
It monitors your heart rhythm continuously. Upon detection of a dangerous rhythm (ventricular tachycardia (VT) and ventricular fibrillation (VF)), the device will either pace or deliver a shock to terminate the dangerous rhythm. The ICD protects patients at risk from premature deaths due to life-threatening heart rhythm. It can also pace the heart when the rate is too slow.
The AICD consists of two parts: first, a box which houses the electronics (the “device”), and second, one or more wires that connect the box to the heart muscle (the “leads”).
This is what an actual AICD looks like. The maximum diameter is around 2 to 3 inches i.e. around the length of your small or ring finger.
Shown here is what a freshly implanted AICD looks like. The incision used to implant the device is around 5 cm long. Usually it is implanted on the left side; occasionally it is implanted on the right side.
Your doctor will recommend an AICD if he thinks you are at risk of developing dangerous abnormal heart rhythms (“VT” or “VF”) and therefore at risk of sudden death. This may be because:
A specialist doctor called an Electrophysiologist will perform the procedure. The procedure will be done in the Electrophysiology Lab.
A device implant is generally a safe procedure. However, as with any invasive procedures, there are risks. Special precautions are taken to decrease your risks.
Your doctor will discuss your risk with you as every individual is different. In general however, the risk of implanting an AICD is low - only 1% or less of serious complications. These include (but are not limited to):
All of these complications are treatable. However, the most common problem with AICDs is that they may deliver unnecessary shocks; if so, your AICD may need to be re-programmed or your medication altered.
The purpose of the AICD is to protect you from sudden cardiac death due to abnormal heart rhythms; your doctor will normally only recommend one if he thinks this risk substantially outweighs the low risk of AICD implantation.
Yes. Your doctor will determine the best suitable device for you, depending on your condition.
Your doctor will arrange a date for you to be admitted to the hospital. Usually you are admitted on the day of the procedure; occasionally, you will be admitted the day before. Most patients can expect to be discharged the following day; occasionally, your hospital stay may be longer if the procedure is difficult or complicated.
Your doctor should already have instructed you on what to do before the procedure.
Please check before discontinuing any medications. The following information is a general guide only.
If you are on warfarin, this will normally need to be discontinued around 5 days prior to the procedure, and a blood test (“INR”) taken to confirm that your blood clotting is normal prior to implantation.
If you are taking aspirin or clopidogrel (Plavix), you may be asked to discontinue one or both of these prior to implantation; however, please confirm this with your doctor.
You can normally continue taking your other medications as usual.
In most cases, you will be told to eat a normal meal the evening before your procedure. However, do not eat, drink or chew anything after 12 midnight before your procedure. This includes gum, mints, water, etc. If you must take medications, only take them with small sips of water. When brushing your teeth, do not swallow any water.
When getting ready, please do not wear makeup and remove nail polish. Wear comfortable clothes when you come to the hospital. You will change into a hospital gown for the procedure. Please leave all jewelry (including wedding rings), watches and valuables at home.
Before the procedure begins, a nurse will help you get ready. You will be given a hospital gown to change into. You may keep your clothes in a locker or you may give them to a family member.
You will lie on a bed and the nurse will start an IV (intravenous) line in a vein in your arm or hand. The IV is used to deliver medications and fluids during the procedure.
To prevent infection and to keep the device insertion site sterile:
You will return from the Electrophysiology Laboratory with pressure dressing over the site of the AICD implant. If you have any pain, please inform your nurse so you can be given enough painkillers.
You will stay overnight in the hospital and usually will be able to go home the day after the device is implanted.
A chest x-ray will be done after the device implant to check your lungs as well as the position of the device and lead(s).
The following day, an Electrophysiology Technician will confirm your AICD is working properly; this is done on the ward, from outside the body.
If there are no problems, you can expect to be discharged the following day with a return appointment in one week. You may also be given a short course of antibiotics to prevent infection.
You will need long term follow up. Initially you will be seen at four to six weeks intervals to check the AICD is functioning as intended. If there are no problems, the follow up interval may be lengthened to every three months or more.
After the AICD is implanted, you will need to keep the implant site clean and dry while the overlying skin heals. On discharge from the ward, the nurses will arrange regular dressing changes.
For two to three weeks after implantation, you should also avoid raising your arm on the side of the implant above shoulder level to avoid dislodging the lead or device. After two to three weeks have elapsed, the lead and device should be secure so that this is no longer an issue and you can move your arm normally.
There are few restrictions from having an AICD. Most sports are permitted except contact sports such as rugby where vigorous impact could damage the AICD.
Swimming is permitted but we do advise common sense precautions such as not swimming in deep water alone.
No. For your safety, a responsible adult should drive you home. Ask your doctor when you could resume driving.
The AICD is battery-powered. How often does the battery need changing and how is it changed?
Most AICDs will last around three to six years or more. We will check on the battery status during your regular clinic follow ups. Changing the battery is similar to implanting a new device except the AICD leads (the wires which connect the device to the heart) do not need to be changed.
Your doctor will discuss the results of the procedure and answer any questions you have. Be sure to ask the doctor if you can continue taking your previous medications.
You will receive specific instructions about how to care for yourself after the procedure including medication guidelines, wound care, activity guidelines, device care and maintenance, and a follow-up schedule.
Yes. Your ID card contains pertinent information about yourself, type of AICD and your physician.
This is made available quickly in the event of an emergency. If you lose your card, please ask for a replacement.
You should always follow your doctor’s instructions about receiving therapy.
Go to A&E or call 995 if you do not feel well or if there are more than 2 shocks delivered in the same day.
You can travel with an AICD. However, you should discuss your travel plans with your physician as there may be other important medical considerations.
The amount of metal used in most AICDs is very small and not usually enough to set off the detector alarm. If it does, inform the security personnel that you have a AICD implanted, and show them your patient identification card.
Passing through the metal detector portal will not harm your device; however do not linger near it as the magnetic field may temporarily interrupt the normal function of the device.
Ultrasound scans (including echocardiograms), as well as X ray scans (including CT scans) do not affect the function of your AICD; you may proceed with these normally.
However, you should not have MRI (magnetic resonance imaging) scans. Such scans use very strong magnetic fields which can affect the function of the AICD.
Keep calm. It is only an indication that you should contact your doctor. If you hear a continuous tone at high frequency, the situation is not urgent; you should phone your doctor and arrange an earlier appointment. However, if you hear a double high and low frequency tone, you must inform your doctor and arrange to see him immediately.
During out-of-hours period, please do visit the A&E.
The risk of implantation is estimated to be about 1%, including excessive bleeding, pneumothorax (air leak from the lung), cardiac perforation, long term risk of infection and device malfunction.
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