Implantable Cardioverter Defibrillator

What is it?

An implantable cardioverter defibrillator (ICD) is an electronic device that like a standard pacemaker has the ability to stimulate the heart in individuals with pathologically low heart rates. In addition to this function, the ICD detects and treats abnormallyfast heart rhythms that are generated from the lower chambers (ventricles) of the heart.

When the ICD detects an abnormally fast heart rhythm (ventricular tachycardia / ventricular fibrillation) using a pre-set sequence of commands, it will deliver a rapid burst of impulses to your heart or a controlled electrical shock to restore the heart’s normal rhythm.


An ICD may be implanted using general anaesthesia, or conscious sedation and local anaesthesia. Antibiotics are given before and occasionally after the procedure to prevent infection.
A small incision is made inthe area of the left chest wall beneath the collar bone to create a pocket for the generator and to access a suitable vein to pass one or more wires (leads) into the heart using x-ray control. The ICD consists of two parts: a ‘’pulse generator ‘’ containing the battery, capacitors and electronic circuits, and one or more leads. Once a suitable location is identified, the leads are screwed or inserted into the heart muscle and then connected to the ‘’ box’’ (pulse generator)

The cardiologist will then close the wound with dissolvable stiches and apply a sterile dressing directly over the area.

What are the risks of ICD implantation?

In general, there is a 1-2% chance of complications which may include:

  1. Collapsed lung (pneumothorax)
  2. Excessive bleeding/bruising
  3. Infection
  4. Damage to the heart muscle and/or blood vessel walls
  5. Blood clots in veins that are used in passing the leads to the heart
  6. A remote possibility of heart attack, stroke or death following the procedure
  7. A small risk of reacting to the antibiotics or dye (contrast) which is occasionally injected to facilitate passage of the wires into the blood vessels
  8. Complications related to the anaesthetic or sedation given during the procedure
  9. ICDs may deliver shocks that are triggered by rhythms other than ventricular tachycardia (VT) or ventricular fibrillation (VF). In one study 13% of patients had inappropriate shocks during 2 years of follow-up. Changes in your medications may be required to prevent this. In addition, recent innovations in ICD technology and how they are programmed has been shown to reduce the incidence of inappropriate shocks.

The actual risk of harm resulting from ICD implantation may be lower or higher, depending on your medical circumstances. The cardiologist will discuss this with you before the procedure.

Before you are discharged from hospital, you will have a chest x-ray, ICD check, ICD identification card and you will be given advice about activities you should or shouldn’t be doing, safety around appliances with magnetic fields and precautions to take at airports.

It is important to remember that if you notice any problems with the healing of the wound you must contact your cardiologist immediately particularly if there is any redness, swelling or pain around the incision site, fever or bleeding from the site. A small amount of bruising following the procedure is completely normal.