Implantable Cardioverter Defibrillators
About Implantable Cardioverter Defibrillators (ICD's)
If medications are not considered the best option or have failed in controlling ventricular tachycardia or ventricular fibrillation, an ICD will be offered - with frequently both conventional and newer devices available. An ICD, which can now be implanted without opening the chest, monitors the heart’s rhythm and if an abnormal rapid rhythm is detected, it sends a varying form of energy back to the heart to restore a normal heartbeat. The device’s generator (about half the size of a deck of cards) is implanted in the chest-pectoral region, like a pacemaker. One or more long, thin wires, called "leads" run from the device to the heart. Additional leads may be placed in or outside the heart, if indicated. These leads then feed the heart’s electrical impulses to the generator for monitoring. When an abnormal signal is received, the preprogrammed device sends up to three different kinds of responses to the heart to rectify the irregularity. Depending on the abnormal rhythm, the ICD may send a series of rapid electrical impulses (probably undetectable to the wearer) called pacing; it may send a low-energy shock (similar to a small thump) called cardioversion; or it may send a high-energy shock (feels like a kick or a blow) called defibrillation.
Living With Your Implantable Defibrillator
An implantable defibrillator has two main parts:
A pulse generator, placed in the upper pectoral region which holds the "brains" and battery of the device.
Wires (called "leads") which connect to the heart. These wires can sense the heart’s rate and can shock the heart if needed.
How it is Implanted
Leads for the defibrillator are usually implanted by threading them through a large vein that goes to the heart. This is called transvenous placement. A small incision is made over a vein in the upper chest. One or two leads are inserted through the vein to the heart. A small patch may also be placed under the skin on the left side of the chest. The ends of the leads and patch are tunneled under the skin and attached to the generator, which is usually placed in the left pectoral region (near your left shoulder, above your left breast). The term "pectoral implant" refers to the fact that the generator is now located near the pectoral muscle in the upper chest.
On rare occasions, the defibrillator leads can be implanted directly over the heart during surgery. Your doctor will advise you if this is the way your leads need to be implanted.
How Your Device Works
During your Electrophysiology Study, or on an ECG or other type of rhythm strip, your doctor has discovered which type of arrhythmia you have and at what heart rate your heart goes into the arrhythmia. When your device is implanted, it will be programmed to detect this rate or problem. When it does, it will try to stop the rhythm in one of three ways. Your electrophysiologist will choose which methods are best for your rhythm problem.
The three ways are:
Pacing (called antitachycardia or fast pacing) – The device may send small, rapid electrical impulses to your heart. These impulses will try to stop your abnormal rhythm and let the normal heart rhythm return. You will probably not feel these pacing impulses.
Cardioversion – The device may send a low-energy shock through the two patches attached to your heart. One or more of these shocks can be sent to convert your fast heart rhythm to a more normal rhythm. You will be aware of the shock even though it is at a low energy level. It may feel like a small jolt in the chest.
Defibrillation – The device may send a high-energy shock to your heart. This shock is needed if the low-energy shock is not successful or if your heart goes into ventricular fibrillation (VF). You will feel this shock – it feels like a kick or a jolt in the chest.
An example of how your device might be programmed:
If your heart goes into an abnormal rhythm at a rate of 160 beats per minute, your device may first try pacing.
If the pacing is not able to stop your fast heart rhythm, the device may try cardioversion (low-energy shocks).
If the low energy shocks are ineffective, or if your heart goes into VF, the device can defibrillate (send one or more higher-energy shocks).
Your implantable defibrillator may also have a back-up pacemaker in case your heart should beat too slowly. This kind of pacing is at a much slower rate than antitachycardia or fast pacing.
Care at home following your implant:
Call your doctor if you notice any fever or redness, swelling or drainage from your incisions.
Follow-Up Care – About one month after your surgery, you will need to come for your first office visit, then you will need to come every four months. During these visits, we will use a special programmer to check the batteries and proper functioning of your device (this is done from outside the body). We can also check to see if you have received any shocks or pacing therapies, as this information is stored in the device’s memory. At certain times we may need to do outpatient testing in the EP lab. We expect the batteries of your device to last from four to five years, at which time only the generator (not the leads) will need to be replaced.
Identification- Before you go home from the hospital you will be given a temporary wallet card with information about your device and an emergency phone number, carry this with you at all times. A permanent plastic card will be mailed to you within several weeks. You will also be given an order form for a Medic Alert chain. We suggest you order a bracelet or chain to help alert medical staff that you have an ICD.
What happens if I receive a shock?
Have a plan of action for any possible problem, even though it may never be needed. Know how to call your local emergency medical system. Keep a current list of your medications and doctors’ numbers near the phone.
If you receive a shock from your defibrillator:
If you are not feeling well (for example, you continue to feel chest pain or dizziness), call the rescue squad and be prepared to be taken to the emergency room.
If you feel fine, call your EP doctor or clinic. During off-hours, phones will be forwarded to an answering service which will page the on-call physician for you. Please be sure to call us whenever you think you have been shocked.
If you receive three or more shocks in a row, call the rescue squad and be prepared to go to the hospital.
If you live in a rural area, you may want to visit your local emergency room or rescue squad. Tell them about your implantable defibrillator and inform them that in case of emergency, the usual methods should be used to treat your heart rhythm problem. We can give them more information at your request, and you may give them our telephone number.
Will my lifestyle change after the implant?
Follow the exercise program prescribed for you, and be sure you have a copy of the booklet "Exercise and Your Implantable Defibrillator".
You may resume most of your activities that do not involve heavy lifting or straining. Your exercise program will include instructions about how much lifting you can do.
Resume driving only when your EP doctor says you may. This is for your safety and the safety of others.
Things to avoid:
Strong magnets or magnetic fields – these can interfere with the action of the device and may even turn the device off. If you work with strong radiofrequency or high-voltage equipment, be sure to discuss this with us.
Airport security – Show the security personnel your ICD identification card and ask that they check you manually.
Contact sports or activities that may inflict blows to the shoulder area.
You may use cell phones, however we recommend that you hold the phone on the opposite side of your ICD, at least 6 inches from the ICD. If your phone transmits more than three watts, increase this distance to 12 inches. Do not carry the phone in a breast pocket.
Ask your doctor about further recommendations regarding magnetic fields.
Resume sexual activity when you feel ready.
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