The Implantable Cardioverter Defibrillator (ICD) is a small, surgically-placed medical device that is saving the lives of many people living with potentially fatal heart rhythms.
- The ICD consists of a small, thin, battery-driven titanium “generator” (about 2/3 the size of an iPod Nano).
- It is inserted beneath the skin just below the collarbone.
- There are two or three wires (called “leads”) attached to the generator.
- The generator contains a battery, capacitors, a computer, and other sophisticated electronics.
- The leads transmit the tiny electrical signals from the heart that control the heart rhythm back to the generator, where they are continuously analyzed.
If a dangerous arrhythmia is detected, within 10-20 seconds, the Implantable Cardioverter Defibrillator automatically delivers a large electrical discharge (a shock) to the heart, which stops the arrhythmia and allows the normal heart rhythm to return.
In addition to delivering shocks that stop cardiac arrest, an Implantable Cardioverter Defibrillator can also function as a pacemaker.
- Pacemakers use tiny electrical discharges to stimulate the heart to beat when the heart rate is too slow.
- In some patients, the pacemaker function of ICDs can also be used to stop episodes of ventricular tachycardia (but not ventricular fibrillation), thus avoiding the need to give a shock.
- Finally, some ICDs can also provide cardiac resynchronization therapy (CRT), which can improve symptoms in people who have heart failure.
All ICDs are “programmable.”
- With a special programmer device that wirelessly communicates with the ICD, the doctor can easily change the way the device functions if the settings need to be adjusted.
But while an Implantable Cardioverter Defibrillator can do all these different things, their core function is to prevent sudden cardiac death in people who are at increased risk for cardiac arrest.
Procedure for placement of an ICD
- The surgery is considered “minimally invasive,” and is usually performed by a Cardiologist, using local anesthesia.
- Once the ICD has been implanted, doctors will test the device to make sure it’s working correctly.
- After the patient is put into a light sleep with a short-acting sedative, the Doctor electronically triggers an arrhythmia (irregular heart rhythm) and the ICD is allowed to detect and stop the abnormal heart rhythm automatically.
- The procedure takes an hour or two, and in most cases, the patient is discharged home on the same day.
- The doctor will want to see the patient four to six weeks after surgery to make sure the surgical site is fully healed and to answer any additional questions.
- Afterward, the doctor will usually see the patient in his/her office two to four times per year.
- During all visits, the ICD will be wirelessly “interrogated” using the programmer, to give the doctor vital information on how the ICD is functioning, the status of its battery, the status of the leads and whether and how often the ICD has needed to deliver either the “pacing” or the “shocking” therapy.
- The newest ICDs are able to send this information to the doctor wirelessly from the patient’s home, through the Internet.
This “remote interrogation” feature allows the doctor to evaluate the ICD whenever needed, without requiring an office visit. Even if the ICD has this remote feature, however, the doctor will want to see the patient in the office at least once a year.