A defibrillator, or the exact medical term, an implantable cardioverter defibrillator or ICD—this is the acronym I’ll be using—an ICD is a battery-powered device.
Here’s an example in the size of the device, that is implanted under the skin, in the chest, close to the heart, and is connected to the heart with a thin wire.
The technical term is a lead.
So the device and the lead continuously monitor the heartbeat of the patient.
If the device detects an abnormal, serious and dangerous heartbeat, it will identify it and correct it.
It will correct it either by what we call overdrive pacing, to pace faster than the abnormal rhythm, which is painless.
And if that doesn’t work, or that is not appropriate, the patient will receive a shock, that will immediately correct that abnormal and dangerous heart rhythm.
The majority of defibrillators also have a pacemaker function that will correct a slow heart rhythm.
Why do some patients need a defibrillator?
ICDs are implanted to prevent sudden cardiac death.
Initially, or often, in patients who have survived a serious rapid heartbeat of the lower chambers of the heart, which we call the ventricles, and the arrhythmia, is ventrical tachycardia or ventricle fibrillation.
When we implant the device in somebody that has survived this abnormal arrhythmia, it’s called secondary prevention.
But very often we implant defibrillators in primary prevention, in patients who have not had a ventricle tachycardia or fibrillation, but who are at high risk of having one.
Most often this is in patients who have a ventricle that has been damaged by a heart attack, and we will then implant the device to prevent a serious arrhythmia or sudden death.
What is the surgical implant procedure?
The procedure is usually done under local anesthesia, with a sedative, so that the patient will be conscious during the procedure.
Sometimes, general anesthesia will be required.
The procedure consists of a small incision, of two to three inches in the skin, usually just below the left collarbone, and then we are able to create under the skin a pouch that will receive the ICD device.
The device is connected with wires, or leads, to the heart, and we place the leads by puncturing a vein in the chest, and then we lead that with X-ray images to the heart.
ICDs either have one lead, in the right ventricle, or a second lead in the right atrium, and sometimes a third lead, which is in the outer surface of the left ventricle.
This third lead is used to resynchronize the ventricle and improve heart failure in some patients.
Now the most recent ICD is called a subcutaneous ICD, which means that there are no leads inside the heart.
The device is usually implanted under the skin, and under the armpit, and the lead is also under the skin and will cross the sternum.
The subcutaneous ICD is implanted usually in patients who have a defect or an abnormality of the vein inside the chest.
Overall, an implantation of an ICD will take between one to two hours.
Patients will stay in hospital for one to two days.
We also explain to the patient that there are some risks.
Complications are not common, overall the risk is about 3 to 5 percent, which includes the risk of an infection, any time we open the skin.
The risk of edema, or collection of blood inside the pouch, these are the most frequent risks associated with the ICD procedure.
If you have any more questions, please call your doctor or your cardiologist, and in some cases you will need to speak with a medical personnel of the defibrillator clinic.