Implantable Cardioverter Defibrillator: Indications and Complications
Your heart beats at a regular rhythm and rate to provide blood rich in oxygen to different parts of your body. Abnormalities in the rate or rhythm of the heart are called arrhythmia. There are many types of arrhythmia like atrial fibrillation (rapid chaotic contraction of atria), ventricular tachycardia (rapid ineffective contraction of ventricles), ventricular fibrillation etc.
An Implantable Cardioverter Defibrillator (ICD) is a small battery powered device that is implanted under the skin to reduce the risk of death due to ventricular tachycardia and ventricular fibrillation.
How does ICD work?
Thin wires connect the ICD to your heart via the blood vessels. The ICD keeps track of your heart rate and can send an electrical impulse to the heart when an abnormal rhythm is detected, to shock it back to normal rhythm. New generation ICD also have pacemaker functions, hence they can provide ‘overdrive’ pacing, to provide an electrical shock to a chaotically beating heart, or a ‘backup’ pacing where an electrical signal can be sent to a heart that is beating very slowly. The newer devices also have the ability to store information about the irregular rhythms, arrhythmia, and perform electrophysiological studies.
Depending on the disorder of heartbeats your ICD will be programmed to provide an electric shock to restore the heart to a normal rhythm:
- Low energy pacing therapy: you will barely feel anything as your ICD sends an electrical signal in response to a mild disruption in heart beats
- Cardioversion therapy: you may feel like someone has thumped your chest as a mild electric shock is delivered to the heart for a more serious abnormality in the rhythm
- Defibrillation therapy: you will feel like someone has kicked your chest as a strong electric shock is delivered to your heart.
Procedure of ICD
To implant an ICD your surgeon will give you a sedative to help you relax during the procedure. As the sedative takes effect the surgeon will administer a local anaesthetic near your collar bone. Alternatively general anaesthesia can also be used. The surgeon inserts a set of insulated wires, via the veins near your shoulder, to your heart. These insulated wires are leads that can carry information about the heart rhythm to the ICD and also deliver the electric shock to the heart. The ends of the lead are connected to a generator which is implanted just under your skin below the collar bone. The doctor will then check if the ICD is working by speeding the heart artificially and shocking it back to normal rhythm.
Indications for ICD
Implantation of an ICD is indicated when you are the risk of a life threatening ventricular tachycardia because of having:
- A congenital heart disease
- History of ventricular tachycardia
- History of heart attack
- Long QT syndrome
- Brugada syndrome
- Survived a sudden cardiac arrest.
Preparation for ICD
To prepare for the implantation of the ICD your doctor would like to order several different types of test to evaluate the health of your heart like and echocardiography, electrocardiogram and holter monitoring. Your doctor might also order an electrophysiological study. Before the surgery your surgeon will discuss different types of ICDs available for you; and will help you make an informed choice on which ICD will be the best for you. Your doctor would like to know about the medications that you’ve been taking and might make a few changes in them before the surgery. You are advised to inform your doctor about any allergies to medication that you have experienced in the past. You will be asked to stop eating and drinking eight hours before the procedure.
Complications of ICD
Complications associated with ICDs are rare, they may be:
- Infection of the site where the ICD is implanted
- Bruising and redness at the site of implantation
- Damage to the blood vessel through which the lead was passed
- Leakage of blood through the valve near which the lead are placed
- Leakage of blood from the heart into the surrounding
- Allergic reaction to the sedative or anaesthetic used
- Pneumothorax.
Recovery after ICD
You will be allowed to go home as the effect of the medications start to wane. It is advisable to arrange for someone to drive you home. You will be advised to avoid driving fro atleast a week after the surgery. After the surgery you might feel slight pain and tenderness at the site of the surgery, your doctor will prescribe pain medications for it. Do not take over the counter pain relief medications that contain aspirin as it may increase the risk of bleeding; consult your doctor before taking and resuming any medications. Your doctor might advise you to refrain from vigorous activity and contact sports for atleast four weeks after the surgery.
On a long term you will have to ensure that you are not in prolonged contact with devices that produce an electric field or a strong magnetic field as they disrupt the working of the ICD. Keep a distance of about 15 cm form cell phones, headphones and metal detectors. At the airport you may show your ID card and ask for an alternative form of inspection. Inform your doctor or dentist that you have an ICD before undergoing a procedure.
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