Implantable cardioverter defibrillator (ICD)

What is it?
A procedure for inserting an implantable cardioverter defibrillator (ICD), a device that regulates irregular heart rhythms by sending an electrical impulse to your heart.

Why is it performed?
An An ICD is implanted tCD is inserted to treat dangerously fast heart rates that occur in the lower chambers of the heart and to prevent sudden cardiac arrest. An ICD looks much like a pacemaker but is designed to detect and treat slow heart rates (bradycardiascardias and fast heart rates (tachycardiascardias. By delivering electrical shocks, the device treats these rhythm disorders and restores a normal heart rate and rhythm. ICDs also have pacing capabilities, keeping the heart beating at a constant rate.

ICDs are usually prescribed for people who have experienced:

• at least one episode of ventricular tachycardia or ventricular fibrillation
• previous cardiac arrest
• drug therapy (medication) has been unable to control the heart rhythm problem, or caused severe or unacceptable side effects

What is done?
Like an artifical pacemaker, the ICD consists of two parts. The leads are wires with electrodes at the tip that transmit electrical signals to and from the heart muscle. The ICD is a small unit with a computer that monitors the heart rhythm and, when necessary, generates an electrical shock. The ICD can be programmed to meet your specific needs. The ICD also stores important information about how the heart is performing that your doctor can periodically retrieve.

There are several ways of implanting the leads of an ICD:

• Transvenous Approach – Transvenous means through a vein. In this method, a small incision is made near your collarbone and the leads are maneuvered through a vein into the heart. The tip of each lead is positioned next to the inside wall of the heart (the endocardium).
• Thoracotomy – In this approach, the chest is opened and thin oval patches made of rubber and wire mesh are sewn onto the outside of the heart (epicardium). These patches are connected to the leads.
• Sternotomy – This approach is similar to a thoracotomy in that the chest is opened. The difference is that the incision is made over the breastbone (the sternum) and the leads are advanced into the heart. A sternotomy may be combined with coronary artery bypass surgery or heart valve surgery.
• Subxiphoid Approach – This approach is also similar to a thoracotomy, but the incision is made slightly to the left of the breastbone (sternum).

Once the leads are in place and tested, they will be connected to the ICD unit. The ICD is then placed under the skin, either near the collarbone or somewhere above or at the waistline.

What can you expect?
Usually, the procedure is scheduled ahead of time. A week or so before your operation, you will probably be asked to visit your hospital. Various tests, such as blood tests, urine tests, an electrocardiogram, and other tests may be performed.

Your doctor will explain the risks and benefits of the procedure and you will be asked to sign a consent form. Before the procedure starts, inform your doctor if you:

• have ever had a reaction to any contrast dye, iodine, or any serious allergic reaction (e.g., from a bee sting or from eating shellfish)
• have asthma
• are allergic to any medication
• have any bleeding problems or are taking blood-thinning medication
• have a history of kidney problems or diabetes
• have body piercings on your chest and/or abdomen
• have had any recent change in your health
• are, or may be, pregnant

Usually, implantation is performed with the patient awake but sedated and the chest area numbed with local anesthetics (similar to the anesthetics dentists use). Testing will be conducted to find the best location for the leads, and to ensure that the leads are connected correctly to the ICD. Once the ICD is implanted, additional testing may be performed to ensure the system will effectively correct your arrhythmia problem.

After the procedure, you will be taken to a recovery room. You will probably feel drowsy and there may be some soreness around the site where the pulse generator was implanted. Discomfort can be managed with pain medication. Depending upon your condition and which procedure you had, you may stay in the hospital for a few days. Before you leave, the ICD system may be tested again.

When you return home, keep an eye on your incisions. Some bruising is normal but contact your doctor if you experience increased pain, redness, swelling, bleeding or other draining from an incision, fever, and/or chills. For the first few weeks, avoid sudden, jerky movements with your arms or stretching or reaching over your head.

ICD sensations in the body
When an ICD delivers its electrical impulse, some patients report feeling a fluttering in their chest with no discomfort or pain. Others say that they feel a “thump” in their chest, but usually only lasts a few seconds.

ICD cautions
In the first few weeks after surgery, your doctor will let you know what activities you may engage in. Driving a car may depend on the extent of your condition and provincial laws. Machines may interfere with the proper functioning of your ICD, especially those with strong magnetic or electric fields such as home shop tools, microwave ovens and airport screening devices. Speak to your doctor.

Last reviewed March 2007.