Implantable Cardioverter-Defibrillator (ICD) Implantation
Ventricular tachycardia and ventricular fibrillation are life-threatening arrhythmias that cause the heart to beat very fast. In ventricular fibrillation the contraction is also uncoordinated and the muscle quivers instead of contracting properly. These conditions can be fatal if not treated immediately.
An implantable cardioverter-defibrillator (ICD) is a small electronic device that is used to monitor a person’s heart rhythm, and if an abnormally fast rhythm is detected it can deliver an electric pulse to restore it to normal.
ICDs are used in people who have had:
- A prior episode of ventricular fibrillation or ventricular tachycardia
- A prior episode of sudden cardiac arrest
- People who are at risk including:
- A prior heart attack
- Hypertrophic cardiomyopathy
- Inherited conditions such as long QT syndrome and Brugada syndrome
ICDs have two main components:
- A pulse generator, which generates electric pulses. It is made of a small computer and long-lasting battery.
- The leads, which transmit the electric pulses to the heart muscle.
ICDs can be set to perform the following functions:
- Anti-tachycardia pacing (ATP) – When the heart beats too fast a series of low-energy electrical impulses are delivered to the heart muscle to restore a normal rhythm. The patient usually does not feel anything.
- Cardioversion – An accurately timed shock is delivered to the heart muscle to restore a normal rhythm. The patient may feel like being thumped in the chest.
- Defibrillation – A high-energy shock is delivered to heart muscle in ventricular fibrillation to restore a normal rhythm. The patient may feel like being kicked in the chest and knocked off their feet. There should be no discomfort after the shock is over.
Modern ICDs are also pacemakers, and can deliver low-energy electrical impulses when the heart is beating too slow too. Find out more about pacemakers here.
About the surgery
In most cases ICDs are inserted under general anaesthesia. An ICD is about the size of a stopwatch. The most common site for implanting the ICD is just under the skin between the collarbone and top of the breast, on either the left or right side.
Once the site has been prepared for the ICD device, the leads are then moved into position in the heart through the veins. This is done using image intensification (a special type of x-ray) to help the surgeon guide the leads into the correct position. Only the tips of the leads stay in contact with the heart. The ICD is then tested and the small incision where the ICD was inserted is sutured closed with dissolving stitches.
Patients usually stay overnight in hospital to ensure the ICD is functioning well and the patient’s heart rhythm is normal. There may be some mild pain, swelling, or tenderness in the area where the pacemaker was placed, that can be relieved with over-the-counter medication. Patients normally return to their normal activates a few days after the surgery. However patients are advised to avoid vigorous activities or heavy lifting for about a month, and avoid driving for up to 6 months.
Risks of the surgery
ICD implantation is generally very safe. There is a small risk of bleeding, infection, damage to nerves, veins or lung, or the leads causing damage to the heart.
If the patient feel a shock from their ICD they should contact their doctor within 24 hours or go to an emergency department right away.
ICDs require checking on a regular basis, usually every 6 – 12 months to ensure problems are detected early and there is enough battery left. Checking is done from outside the body using a radiowave programmer, so no invasive procedures are required.
An ICD battery usually lasts between 4 and 8 years, depending on how many shocks it delivers. When the battery runs down a new ICD needs to be implanted, though the original lead usually do not need to be replaced.
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All patients should consult their cardiothoracic surgeon for specific information about their medical condition and surgery.