An automatic implantable cardioverter defibrillator (AICD), sometimes known as an ICD, continuously monitors your heart for any rapid and/or irregular heart rhythms (arrhythmias). When the ICD detects an arrhythmia, it delivers therapy to your heart automatically. It is used primarily to treat ventricular rhythms and to prevent sudden cardiac death.
What causes an arrhythmia?
You might have been born with an arrhythmia (congenital). It may be caused by coronary artery disease or by damage to the heart muscle following a heart attack. Arrhythmias also occur in individuals with weakened heart muscle (cardiomyopathy). ICDs have been implanted in people from age ten through their eighties. The average person is in his or her sixties.
Why is it needed?
Most likely your doctor ordered this procedure for one of two reasons. You might have survived a sudden cardiac death (SCD) experience. Sudden cardiac death may be caused by a variety of cardiovascular diseases and is due to a serious arrhythmia.
If not, you probably underwent an Electophysiology Study (EPS) which is a test designed to diagnose arrhythmias. You might have had other diagnostic tests including an electrocardiogram, an echocardiogram or holter monitoring, which determined you are at higher risk of having a dangerous arrhythmia in the near future.
You may have an arrhythmia called “ventricular tachycardia” (VT or V-tach). This consists of very fast but regular heart beats originating from the lower chamber of your heart. Your heart will not pump as efficiently as it does during a normal rhythm. You may feel it pound. You may feel faint or dizzy. It may be unnoticed by you so far.
You may have an arrhythmia called, “ventricular fibrillation” (VF). VF is an unstable heart rhythm during which your heart beats in a disorganized manner. Your heart will stop pumping blood and you will suffer a temporary loss of oxygen. You will usually pass out within a few seconds.
These conditions are life threatening without treatment.
How is treatment delivered?
If your heart goes into one of these rapid rhythms, the ICD can deliver an electrical shock to it, which stops the quivering of the heart, and restores normal heartbeats. This is called “defibrillation.”
In some cases, the ICD can deliver smaller electrical shocks to stop the fast rhythm and restore normal heartbeats. This is called “cardioversion.”
Other times, ICDs can also deliver a series of small, rapid pacing impulses to restore normal heart rhythm. The ICD will not deliver further treatment or shock. You may not feel this. This is called “Anti-Tachcardiac pacing (ATP).”
Finally, perhaps your heart beats too slowly. This is called bradycardia. If you have bradycardia, the ICD will work as a pacemaker. It will deliver small impulses to pace your heart until it recovers and maintains a normal rate.
What do the therapies feel like?
If you fainted or became unconscious shortly after VF rhythm started, you will not feel the high energy defibrillation shocks. If you are conscious, the shock may feel like a “kick in the chest.” Usually, the shock comes suddenly. The sensation lasts for only a fraction of a second. Reactions vary. You may find it reassuring; you may find it briefly uncomfortable.
Cardioversion low-energy shocks are stronger than pacing pulses. You may find cardioversion uncomfortable. It may feel like a “thump on the chest.”
You may not feel anything at all with anti-tachycardic pacing. You may feel a fluttering in your chest. You may feel slight discomfort.
Bradycardia pacing pulses are very low energy. You probably will not feel it.
What happens during the procedure?
Usually, the ICD is implanted on the left or right upper portion of your chest muscle just below the collarbone. Sometimes, it is implanted in the abdominal area. The ICD is lightweight and smaller than the palm of a man’s hand. It consists of a generator (computer and battery) and one or more leads (wires).
Most times, the procedure is performed under local anesthesia. You will be hooked up to an intravenous (IV) line and will receive sedation so that you will likely sleep throughout the procedure.
The physician will give you numbing (local anaesthetic) and then make an incision just below the collarbone. A large intravenous line will be inserted through a big vein and through it a wire will be passed into your heart using X-ray equipment. Sometimes two wires will be used. Tests of the equipment will be made. The physician will create a “pocket” in your chest, where he or she will insert the ICD. With all the equipment in place the physician will test the position by creating an arrhythmia and then observing whether the ICD easily delivers the needed treatment. The incision is then closed by stitching.
The procedure usually takes about two hours.
What happens after the operation?
After the operation, you will be taken to a recovery room where you will remain for a little while. Then you will transferred to a monitored room (likely the same room you occupied before the procedure). You can eat as soon as you are awake enough. It’s normal to feel some pain. Do not hesitate to ask the nurse for pain medication. You will most likely get another chest X-ray that evening.
The next day, your ICD system will be checked and tested again with a computer called a “programmer.” This procedure is called “noninvasive programmed stimulation” or “predischarge testing.” You will receive sedation. The doctor will provoke an arrhythmia to see if the device works. The ICD will deliver a shock (defibrillation). The staff will adjust the equipment. You will again get a X-ray before you are discharged home.
What happens at discharge?
You will be shown how to examine your incision site. You should look for signs of infection each day: increased redness, increased tenderness, swelling around the incision, drainage from the incision. You should also report a fever of longer than 24 hours duration. Your will receive instructions for the first few weeks following your discharge, as to exercise, bathing and walking.
After a few weeks, you will visit the doctor who implanted the ICD for a follow-up. At that time your chest will be inspected for bleeding or infections. The equipment will be tested again without provoking a rhythm disturbance. You will continue to visit your doctor every three to four months for similar checks.
Will my lifestyle be affected by this implant?
There will be a few changes in your life; some of them will be temporary. For example, your doctor will ask you not to drive your car for a while. You may be aware of the ICD in the beginning, but you will adjust to it. You will be restricted from lifting any heavy objects or raising you arm above the shoulder level for two weeks.
You will gradually resume your normal lifestyle. This will include returning to your job, traveling, exercise, sexual activity, pursuing hobbies and recreational activities.
You will receive an identification card for your wallet, which has information about your ICD and emergency instructions. At the airport, you should not walk through the metal detector because your ICD’s metal case may set off an alarm. Don’t let anyone place a hand-held screening wand near your ICD because the repetitive motions of the wand may temporarily interfere with the proper operation of your implant. Present your identification card and request a hand search.
You will have to avoid the following:
- Electronic equipment that may present a strong magnetic field.
- Magnetic Resonance Imaging scanner (MRI).
- Stereo speakers that are held in close proximity to the device.
- Smelting or induction furnaces or arc welders.
- Junk yards that use large magnets.
- Large generators or power plants.
- CB or HAM radio antennae.
- Large or defective electronic motors.
- Amusement park attractions and rides where magnets are used.
- Auto engines with poorly shielded ignitions.
- Working on car engines while they are running.
- Using cellular phone on the side where the ICD is implanted.
- Hand-held wands at bingo games.
- Tight clothing over your ICD.
Common household appliances should not affect the ICD if they are used as intended. These include televisions, computers, power hand tools, hair dryers and microwave ovens.
Tell your other doctors and dentist about your ICD. Consult your physician before buying over-the-counter medications and before taking a trip, vacation or moving. Eventually, you will be able to lead an active lifestyle and may be able to do things you couldn’t do before.