Implantable cardioverterdefibrillator


The implantable cardioverter-defibrillator (ICD) is a surgically implanted electronic device that directs an electric charge directly into the heart to treat life-threatening arrhythmias.


The implantable cardioverter-defibrillator is used to detect and stop life-threatening arrhythmias and restore a productive heartbeat that is able to provide adequate cardiac output to sustain life. The exact indications for the implantation of the device are controversial, but patients suffering from ventricular fibrillation (unproductive heartbeat), ventricular tachycardia (abnormally fast heartbeat), long QT syndrome (an inherited heart disease), or others at risk for sudden cardiac death are potential candidates for this device. A study by the National Institute for Heart, Lung, and Blood of the National Institutes of Health showed a significant increase in survival for patients suffering from ventricular arrhythmias when ICD implant is compared to medication. Several follow-up studies indicate that this may be due to the marked increase in survival for the sickest patients, generally defined as those having a heart weakened to less than 50% of normal, as measured by the ability of the left side of the heart to pump blood. Overall, studies have documented a very low mortality rate of 1–2% annually

To place an implantable cardioverter defibrillator, a lead wire is inserted into the cephalic vein of the shoulder and fed into the heart chambers (B). An electrode is implanted in the heart muscle of the lower chamber, and the device is attached (C). (Illustration by Argosy.)
To place an implantable cardioverter defibrillator, a lead wire is inserted into the cephalic vein of the shoulder and fed into the heart chambers (B). An electrode is implanted in the heart muscle of the lower chamber, and the device is attached (C). (
Illustration by Argosy.
for persons implanted with the device, compared to approximately 15–25% for patients on drug therapy.


ICD implant is limited to patients that face the risk of sudden cardiac death from sustained ventricular arrhythmia, including ventricular tachycardia and ventricular fibrillation. Less than 1% of the more than 100,000 device implants done in the United States are performed on pediatric patients. Reduction in the risk of sudden cardiac death improves to less than 2% for both populations.


Patients experiencing syncope (fainting) will be monitored with a cardiac monitor for arrhythmias. Following unsuccessful medical treatment for sustained ventricular arrhythmias, ICD implant will be indicated.


Similar in structure to a pacemaker, an ICD has three main components: a generator, leads, and an electrode. The generator is encased in a small rectangular container, usually about 2 in (5 cm) wide and around 3 oz (85 g) in weight. Even smaller generators have been developed, measuring 1 in (2.5 cm) in diameter and weighing about 0.5 oz (14 g). The generator is powered by lithium batteries and is responsible for generating the electric shock. The generator is controlled by a computer chip that can be programmed to follow specific steps according to the input gathered from the heart. The programming is initially set and can be changed using a wand programmer, a device that communicates by radio waves through the chest of the patient after implantation. One or two leads, or wires, are attached to the generator. These wires are generally made of platinum with an insulating coating of either silicone or polyurethane. The leads carry the electric shock from the generator. At the tip of each lead is a tiny device called an electrode that delivers the necessary electrical shock to the heart. Thus, the electric shock is created by the generator, carried by the leads, and delivered by the electrodes to the heart. The decision of where to put the leads depends on the needs of the patient, but they can be located in the left ventricle, the left atrium, or both.

According to the American College of Cardiology, more than 100,000 persons worldwide currently have an ICD. The battery-powered device rescues the patient from a life-threatening arrhythmia by performing a number of functions in order to reestablish normal heart rhythm, which varies with the particular problem of the patient. Specifically, if encountered with ventricular tachycardia, many devices will begin treatment with a pacing regimen. If the tachycardia is not too fast, the ICD can deliver several pacing signals in a row. When those signals stop, the heart may go back to a normal rhythm. If the pacing treatment is not successful, many devices will move onto cardioversion . With cardioversion, a mild shock is sent to the heart to stop the fast heartbeat. If the problem detected is ventricular fibrillation, a stronger shock called a defibrillation is sent. This stronger shock can stop the fast rhythm and help the heartbeat return to normal. Finally, many ICDs can also detect heartbeats that are too slow; they can act like a pacemaker and bring the heart rate up to normal. ICDs that defibrillate both the ventricles and the atria have also been developed. Such devices not only provide dual-chamber pacing but also can distinguish ventricular from atrial fibrillation. Patients that experience both atrial and ventricle fibrillations, or atrial fibrillation alone, that would not be controlled with a single-chamber device are candidates for this kind of ICD.


ICD insertion is considered minor surgery, and can be performed in either an operating room or an electrophysiology laboratory. The insertion site in the chest will be cleaned, shaved, and numbed with local anesthetic. Generally, left-handed persons have ICDs implanted on the right side, and visa versa, to speed return to normal activities. Two small cuts (incisions) are made, one in the chest wall and one in a vein just under the collarbone. The wires of the ICD are passed through the vein and attached to the inner surface of the heart. The other ends of the wires are connected to the main box of the ICD, which is inserted into the tissue under the collarbone and above the breast. Once the ICD is implanted, the physician will test it several times before the anesthesia wears off by causing the heart to fibrillate and making sure the ICD responds properly. The doctor then closes the incision with sutures (stitches), staples, or surgical glue. The entire procedure takes about an hour.

Immediately following the procedure, a chest x ray will be taken to confirm the proper placement of the wires in the heart. The ICD's programming may be adjusted by passing the programming wand over the chest. After the initial operation, the physician may induce ventricular fibrillation or ventricular tachycardia one more time prior to the patient's discharge, although recent studies suggest that this final test is not generally necessary.

A short stay in the hospital is usually required following ICD insertion, but this varies with the patient's age and condition. If there are no complications, complete recovery from the procedure will take about four weeks. During that time, the wires will firmly take hold where they were placed. In the meantime, the patient should avoid heavy lifting or vigorous movements of the arm on the side of the ICD, or else the wires may become dislodged.

After implantation, the cardioverter-defibrillator is programmed to respond to rhythms above the patient's exercise heart rate. Once the device is in place, many tests will be conducted to ensure that the device is sensing and defibrillating properly. About 50% of patients with ICDs require a combination of drug therapy and the ICD.

Morbidity and mortality rates

Perioperative mortality demonstrates a 0.4–1.8% risk of death for primary non-thoracotomy implants. The ICD showed improved survival compared to medical therapy, improving by 38% at one year. There is a 96% survival rate at four years for those implanted with ICD. Less then 2% of patients require termination of the device, with a return to only medical therapy.

Normal results

Ventricular tachycardia can be successfully relieved by pacing in 96% of instances with the addition of defibrillation converting 98% of patients to a productive rhythm that is able to sustain cardiac output. Ventricular fibrillation is successfully converted in 98.6–98.8% of all cases. Atrial fibrillation and rapid ventricular response leads to erroneous fibrillation in as many as 11% of patients.


Environmental conditions that can affect the functioning of the ICD after installation include:

Environmental conditions often erroneously thought to affect ICDs include:

Patients should also be instructed to memorize the manufacturer and make of their ICD. Although manufacturing defects and recalls are rare, they do occur and a patient should be prepared for that possibility.


In general, if the condition of the patient's heart, drug intake, and metabolic condition remain the same, the ICD requires only periodic checking every two months or so for battery strength and function. This is done by placing a special device over the ICD that allows signals to be sent over the telephone to the doctor, a process called trans-telephonic monitoring.

If changes in medications or physical condition occur, the doctor can adjust the ICD settings using a programmer, which involves placing the wand above the pacemaker and remotely changing the internal settings. One relatively common problem is the so-called "ICD storm," in which the machine inappropriately interprets an arrhythmia and gives a series of shocks. Reprogramming can sometimes help alleviate that problem.

When the periodic testing indicates that the battery is getting low, an elective ICD replacement operation is scheduled. The entire signal generator is replaced because the batteries are sealed within the case. The leads can often be left in place and reattached to the new generator. Batteries usually last from four to eight years.


Patients are treated with medical therapy to reduce the chance of arrhythmia. This alternative has been shown to have a higher rate of sudden death when compared to ICD over the initial three years of treatment, but has not been compared at five years. If the site of ventricular tachycardia generation can be mapped by electrophysiology studies, the aberrant cells can be removed or destroyed. Less then 5% of patients suffer peri-operative mortality with this cell removal.



Gersh, Bernard J., ed. Mayo Clinic Heart Book. New York: William Morrow and Company, Inc., 2000.


Gregoratos, Gabriel, et al. "ACC/AHA Guidelines for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices." Journal of the American College of Cardiologists 31, no. 5 (April 1998): 1175–1209.

Moss, A. "Implantable Cardioverter-Defibrillator Therapy: The Sickest Patients Benefit Most." Circulation 101 (April 2000): 1638–1640.

Sears, Samuel F. Jr., et al. "Fear of Exertion Following ICD Storm: Considering ICD Shock and Learning History." Journal of Cardiopulmonary Rehabilitation 21 (January/February 2001): 47.


American Heart Association. National Center. 7272 Greenville Avenue, Dallas, TX, 75231-4596. (214) 373-6300. .

North American Society of Pacing and Electrophysiology. 6 Strathmore Road, Natick, MA, 01760-2499. (508) 647-0100. .


"Implantable Cardioverter-Defibrillator." American Academy of Family Physicians. May 7, 2001. .

"Implantable Cardioverter-Defibrillators (ICDs)" North American Society of Pacing and Electrophysiology. 2000. .

Michelle L. Johnson, MS,JD
Allison J. Spiwak, MSBME


Electrophysiologists are specially trained cardiologists or thoracic surgeons who study and treat problems with the heart conduction system. In a hospital operating room, they often implant the ICD system and oversee the programming or reprogramming of the device. Electrophysiologists receive special continuing medical education to provide successful implantation. Implantation, follow-up, and replacement can be limited at any one institution, therefore an experienced well-trained electrophysiologist should perform these procedures.


User Contributions:

I found it very satisfactory in answering my questions. My husband is due to have this done on aug.6th. thanks
I would welcome comment on the issue of the need to have routine annual arrhythmia induction to test ICD function in the absence of any problems by routine monitoring, no clinical cardiac issues, no shocks etc. Some medical centers/EPs are advocating this with scaring letters to patients, others do not. Is there any concensus being developed? It is not sufficient to tell patients that the Electrophysiologist thinks it is advisable. There can be advers effects and dangers with the procedure, and patients are very apprehensive about undergoing elective stopping the heart.
I am a coding technologist and have a few questions regarding how these ICD implants would be coded. It is more in regards to replacement of a ICD. When these are being replaced my understand is that the whole device is being replaced with a brand new device. First is this correct? Second - Would it still be considered a new device if the leads are not being replaced? We have another procedure code that is strictly for the removal and replacement of cardiac leads. I am having trouble with this topic because I am receiving two different answers from two different sources. One is stating because the body of the ICD is being replaced that it is considered a new device, and the other is saying that because the leads are not being replaced as well that this is not considered a new device. That is it considered management of the current device. That you would only code this procedure to removal of the leads. Can you please help. Thank you!
I, Ira l. Jackson have a question for the at the national institute for heart,lung and blood,for removals of icd defibrilator and leads, my question is, not complicated but rather reasonalble question, my entire surgery, has to be repeated, due to recall irresponsibility of medical watch for up dates and post market approval however my entire surgery procedure is was done with a unapproved icd medical device, main leads, and recal sprint quattro leads, can this removal be done? and if so can your facility review medical records to see if this medical procedure was needed at all, if records were avalible,? condition that was used was congestive heart failure, i disagree, due to enviromental technological pioson disorders that caused a pancratic attack is not comon for a congestive heart failure,
I'm on my second ICD. I received the first one in 2003. What is the longest a patient has survived after receiving ICD implant? What is the average lifespan of ICD recipients? Thanks
I have read all of the above. But where are the answers for the questions ? I am going to have this done soon and as most people I have many questions. Thanks
My Husband is about to have his 3rd ICD implanted and they want to add a second wire to the auricle. This is more complicated than the one wire to the ventricle. What are the benefits of the second wire?
Mary LaClair
Can solar flares or lightening affect implanted cardioverter defibrillators?
I am due a replacement icd I know it is all done in one day can I drive straight after surgery
Connie B
Can strong electromagnetic pulses (EMPs) from solar flares impact the ICD? Also, how do you find the answers to these questions?
Carol Davis
My husbands defib migrated causing the need for surgery to remove defib and create an opening in his chest to drain pus and blood - after which a wound vac was inserted. He was in critical care for weeks and then in rehab. However, he is very weak and very tired. A decision will be made this week to see if a new defib must be installed after wound is completely healed. Are the aftereffects my husband is suffering - including fecal incontinence normal? The rehab has said there is nothing more that can be done - but his ability to transfer (he has an amputation) from bed to wheelchair and from wheelchair to toilet (there has been no help in the rehab for toileting) are severely impaired.
My son's ICB was inserted 3 months ago. His present cardiologist told him he thought they jumped the gun by giving him this defibrillator as he did not think my son's heart damage warranted it. However, today he has been shocked 3 times. Every time he was shocked, he was touching something metal. The last time he got shocked, he actually saw what looked like a lightning bolt coming from our outside lights and hit him in the back. Is the ICD a conductor of electric? Is there something wrong with the ICD? It never kicked in before today and the last shock did not seem to be from the defibrillator. Can you tell me if there is some kind of connection?
josephine murphy
Since I have an ICD implant, I would like to see the answers to the above questions. Can you please tell me where I can find them. I would like to know how safe my ICD is in a lightening storm?? or if there is any precautions I should take if caught out in thunder and lightening.
j wescott
my husband has an icd implant he is 54 years old his heart is only pumping at 10 per cent its been in for allmost 3 months.he had a lot of fluterring we went to dr. and pacemaker clinic they tweeked it to the lowest it could go he has a third wire dr wanted it tweeked back to where it had been when she hooked him up the third wire is not working we think it moved what happens now more surgery to replace wire
Sheila Cranmer-Gordon
am I safe in a thunder and lightening storm? I have a. Pacemaker and defibrillator fitted.
I am scheduled for May 1 to have my third ICD put in. Wish I had never got the first one and just trusted God to live as long as I was to. It helps 2% live longer, so I read today. Terrible pain when it shocks you, esp. more than once. Putting your heart in a dangerous rhythm to see if it works is bad, and is like waking patients up at night to give them a sleeping pill.I don't say not to get one. You might be the lucky 2%. Never jar yourself. That really makes it go off-like dancing. They asked me to put that third wire in and said it doesn't help some, and can make others worse, but helps a few. I passed it up.They say I should think about a heart pump, but no thanks. That really has the side effects. Living a long life would be nice, but sometimes the pain we go through might out-weigh the joy of life. As Hank Williams sang, "No matter how we struggle and strife, we will never get out of this world a life."Hope he gets better, though.
My Dad needs an ICD but is allergic to silicone. What are is options and who would we contact. That have postpone inserting it for this reason.
Doctor said to stay clean from drugs before this surgery so my heart can be question is is eight days clean Will my heart be strong enough for this percedure?
March 11,2014 my husband had his replaced this was his 3 red one low battery day before told us wouldn't need another one his heart improved but it was still 12 % off so we had it done. A 2 hours after we had it done the unit shocked him 4 times the last one took his life . Trying to fine someone to run a test on the unit to see what happen. I believe it was a short with one of the leads. He was talking to me and said the dam thing just shocked me so I called hospital said come back will see what kind of shock we didn't make it out of our house. Been to two lawyers and my time is running out if anyone out there can help please email me. I just want to know what happen and if the unit or lead was the trouble I want what's right! thank so much for reading this. Need to find some one to run a test on unit to see if it says what happen!
March 11,2014 my husband had his replaced this was his 3 red one low battery day before told us wouldn't need another one his heart improved but it was still 12 % off so we had it done. A 2 hours after we had it done the unit shocked him 4 times the last one took his life . Trying to fine someone to run a test on the unit to see what happen. I believe it was a short with one of the leads. He was talking to me and said the dam thing just shocked me so I called hospital said come back will see what kind of shock we didn't make it out of our house. Been to two lawyers and my time is running out if anyone out there can help please email me. I just want to know what happen and if the unit or lead was the trouble I want what's right! thank so much for reading this. Need to find some one to run a test on unit to see if it says what happen!
Hello .
My father has just been told he's dying , he has c.o.p.d . He had his defibrillator turned off today and we are all in pieces . He still has is pace maker but I know this will not interfere with a peaceful death whereas the defibrillator could cause an agonising one so not not much choice in reaching the sad decision to deactivate. The docter s have informed us he could go at any time or could be here till Christmas , just about two months . We have our lovely Dad at home and will continue to nurse him , he is also on oral morphine as and when required. Bit of a question ,but are there any studies on how long you can last once deactivation takes place ? Ive searched online to try to see how much longer my lovely Dad will be with me but cannot find anything apart from advice on when to deactivate and how .
Many thanks if you feel you may be able to answer my question . Lorraine.
I am 19 years old and was held in the hospital and forced by the doctor to have a defibrillator placed on my healthy heart. EKG, Cardiac Enzymes and electrophysiology test all revealed a healthy heart. How do I get this device removed and where? Attorneys won't take the civil suit case, no money for them.

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