The heart is a hollow, muscular organ with four chambers.
- The top two chambers are called the left and right atrium. The right atrium receives blood from the body. The left atrium receives blood from the lungs.
- The bottom two chambers are called ventricles. The right ventricle receives blood from the right atrium and pumps it out to the lungs. The left ventricle receives blood from the left atrium and pumps it out to the rest of the body.
- The heart's normal pacemaker initiates contractions of its four chambers in a regular, coordinated rhythm. A normal resting heart rate for is sixty to one hundred beats per minute. The beats happen at regular intervals.
- An arrhythmia can cause the heart to beat irregularly (i.e., at varying intervals from beat to beat) and at abnormally fast or slow rates.
Electrical impulses that result in life threatening fast and irregular heartbeats (arrhythmias) typically start in the ventricles.
- Ventricular tachycardia is a type of rapid heart rate that results from abnormal electrical activity in the ventricles. This arrhythmia is frequently ineffective in pumping blood and can lead to ventricular fibrillation and cardiac arrest. Sometimes ventricular tachycardia stops on its own with no treatment.
- Ventricular fibrillation is when the ventricles quiver at a rapid rate, which is ineffective in pumping blood and leads to cardiac arrest.
An implantable cardiac defibrillator (ICD) is a device that detects life-threatening arrhythmias and gives an electrical shock to restore the heart's normal rhythm.
- The symptoms felt when an ICD discharges depend on the arrhythmia and the electrical current that is discharged by the ICD.
- You might feel nothing, a minor skipping of your heart or like you were just kicked in the chest.
- Any discomfort after the ICD discharges should be brief and resolve quickly.
- A normal heartbeat usually returns after a single shock. If several shocks occur during a brief period, seek medical attention for evaluation.
ICDs are typically inserted just below the collarbone, in the soft tissue outside the ribs. It is made up of leads and a generator.
- The leads conduct electrical impulses from the generator to the heart muscle.
- The generator is a small device that is inserted under the skin. It is powered by a lithium battery, which usually lasts from four to six years.
- How long the battery lasts depends on how often the ICD needs to restore your normal heart rhythm.
- The generator can be analyzed and programmed electronically, even after insertion.
An implantable cardiac defibrillator (ICD) may be recommended if:
- You have survived an episode of a life-threatening irregular heartbeat that was not associated with a heart attack.
- You are at a high risk for cardiac arrest because you have a history of a heart attack, an enlarged heart or heart failure.
- You have certain congenital (present at birth) heart problems or genetic health conditions, such as long QT syndrome.
There are several types of ICDs. Newer ICDs also have the ability to act as a pacemaker. The type of ICD your healthcare provider recommends will depend on your:
- General health
- Medical history
- Current diagnosis
- Provider preference
Implantable cardiac defibrillators are used to interrupt a very fast and/or irregular heart rhythm. To see if an ICD is the correct treatment for you, your healthcare provider will do a complete physical exam and likely recommend some tests.
- An electrocardiogram (EKG) will reveal problems with your heart rate or rhythm that are present at the time of the recording. Holter monitoring can provide a continuous recording of your heart's electrical activity for twenty four to seventy-two hours.
- A chest x-ray can show if your heart is enlarged, inflamed, or surrounded with fluid. Other types of cardiac imaging will be done, such as an echocardiogram (heart ultrasound) or heart nuclear scan (studies heart function and blood flow).
- An electrophysiology study (EP study or cardiac mapping) may be done to detect arrhythmias and problems with your heart's electrical system.
An ICD is typically inserted by a cardiologist in a cardiac catheterization laboratory or electrophysiology laboratory (EP Lab). You will receive anesthesia to keep you comfortable and pain free.
- General anesthesia is when you are put into a deep sleep and are unable to see, hear or feel anything. In some cases, local anesthesia and a relaxing medication may be used.
- Your cardiologist will create a "pocket," by numbing the area and making a small incision in the skin under your right or left collarbone. (Tell your doctor if you have a preference for which side you would like the generator placed.)
- The generator will be placed in the pocket and the lead wires will be threaded to your heart.
After insertion of an ICD, you may need to stay in the hospital for a day or two.
- After the procedure, a chest x-ray will be done to confirm proper positioning of the leads. It will also check for any possible problems.
- Additional electrocardiograms may be done before you are discharged.
- You may need pain medication and help at home while you recover.
Do not forget to ask your cardiologist for any specific instructions to follow after surgery. This can include not driving or lifting your arm above your shoulder for a week. Although you may be able to resume most normal activities right away, you should avoid strenuous activities for at least two weeks.
- Before you drive, check with your healthcare provider about the rules for people driving with an ICD in place.
- Before medical or dental procedures, let the provider know you have an ICD.
- If you are a smoker, you should quit smoking, as it can interfere with your recovery.
Contact your healthcare provider if
- Your ICD is firing frequently
- Your original symptoms return
- Your pulse becomes abnormal
- You develop prolonged hiccups
- Your arm or chest muscles are twitching
Also known as:
If your healthcare provider recommends an ICD, ask him or her the following questions.
- Do I need any special tests? What are the benefits and risks of having the tests?
- Will the tests change your treatment recommendations? If not, is there a need for them?
- Why do I need a defibrillator? What are my other treatment options? What is the best treatment for me? What are the risks of each one?
- What different types of defibrillators are there? What are the advantages and disadvantages of each? Which offers the best value for a person of my age and state of health?
- After the defibrillator is inserted, what symptoms should I be concerned about?
- What precautions do I need to take?
- Can my symptoms be controlled with medications? If so, are their Tier 1 or Tier 2 medications on my Prescription Drug List that I should take? How long will I need to take these medications?
- How often do I need to follow up with you? How often do I have to have the defibrillator checked? How do I know if it is working correctly?
Prior to discharge, you should understand all home care instructions. This includes symptoms to report before your next appointment, medications and their side effects, and follow-up plans.