AICD

How Can People Find Out If They are At Risk for Sudden Cardiac Death (SCD)?

There are a number of tests that will help determine if heart attack survivors and people with other conditions that may put them at risk for SCD will benefit from ICD therapy. These include:

• Echocardiogram. The first test performed is usually an echocardiogram, which will determine whether the heart's pumping function is impaired.
• A Holter monitor is an external device worn by an individual who may be at risk for heart rhythm disorders.
• An event recorder is a small, pager-sized device that also records the electrical activity of the heart.
• An electrophysiology study (EPS) is a test that can predict if an individual is at high risk for SCD. In this study, electrical signals (pacing) are administered to the heart muscle through a thin tube called a pacing catheter to see if they will stimulate ventricular tachycardia, the too-rapid heart rate that often leads to VF and SCD. The test is performed in a safe and controlled electrophysiology laboratory at a hospital or clinic and the patient is in no danger.

Why am I having ICD

The Heart Rhythm Society have developed guidelines to help physicians and patients decide whether an ICD is the best treatment for an individual at risk for SCD. For example, it is agreed that ICD therapy is of benefit for:

• Secondary Prevention. This includes individuals who have suffered a prior cardiac arrest or who experience spontaneous, sustained episodes of ventricular tachycardia (VT) that is not self-correcting), especially if they also have episodes of unexplained fainting. VT is a too-rapid heartbeat that can lead to VF.
• Primary Prevention. This is treatment for patients who have never experienced the deadly heart rhythm disorders that lead to SCD, but have significant risk factors for the conditions. This includes certain patients with an ejection fraction of less than 35 percent and documented episodes of VT that are self-correcting and cause no adverse symptoms, but in whom sustained VT can be induced during the electrophysiology study. Ejection fraction is a measure of the amount of blood pumped out of the heart with each beat. An ejection fraction below 55 is considered abnormal.

How Does an AICD Differ from a Pacemaker?

Both an AICD and a pacemaker are devices that are implanted under the skin and connected to wires, or leads, that are placed in the heart. Both continuously monitor the heart to detect changes in its natural rhythm. A pacemaker, however, is used to detect a too-slow heart rate (bradycardia). When it senses that the rhythm is too slow, it sends an electrical signal to stimulate (pace) the heart so it continues its normal electrical beat. The electrical signal that is sent from the pacemaker is strong enough to stimulate the heart to beat, but not strong enough for the patient to feel. An AICD, on the other hand, detects a too-rapid or chaotic heartbeat and delivers a stronger electrical shock to restore the heart to its natural beat. AICDs also act as pacemakers.

Risk or complications

ICD implantation is a routine procedure and complications are rare. However, like any surgical procedure, there is a small degree of risk. The doctor discuss these risks and complications with you before you consent to the procedure.

Some of risks associated with ICD implantation are: puncturing the lung or heart tissue, infection and bleeding around the wound site or ICD leads. However, the benefits of having an ICD far outweigh the minimal risks. The primary benefit for having ICD implanted is prevention of sudden cardiac death as a result of ventricular arrhythmia.

Alternative treatments

There is no recognised alternative current medical treatment for prevention of sudden cardiac death from ventricular arrhythmias. A large number of clinical trials have shown ICDs to be the optimum treatment. Drug therapy (anti-arrhyhmics) have shown some benefit but are inferior to ICD therapy, and have a number of significant side effects.

On the day of the implant procedure

You will be asked to report to the Cardiac Catheter Laboratory by 8am. You are advised not eat or drink 12 hours before your procedure. You will be asked to complete some forms to confirm your personal details and previous medical history, andyou will be required to formally give your consent to the procedure. There will be an opportunity to ask the doctors about any concerns.

You will be taken to the ICD lab where your procedure will take place. Normally ICD implant patients receive local anaesthetic and are sedated for their procedure. General anaesthetics are not usually required for this type of procedure. During the procedure staff will make every effort to keep you as comfortable as possible. If you experience any discomfort or pain, please alert a member of the team who will be able offer assistance.

During the implant

Before the procedure commences a cardiac physiologist will explain the procedure to you and connect you to various pieces of monitoring equipment. This will involve attaching sticky ‘patches’ (electrodes) to your arms, legs and chest. The nurses will clean the area where the device is to be implanted with a special disinfecting solution, and cover you with sterile drapes. Once the drapes are on, it is important to keep movement to a minimum as it could de-sterilise the area.

Where ICD leads and device are implanted.

The doctor will administer a local anaesthetic to numb the area just underneath the collarbone. They will then make a small cut (incision) a few inches long just below your collarbone. The device will be slipped in under your skin or muscle. One, two or three wires called ICD leads will be advanced into your heart chambers through the veins in this area, using X-ray guidance, and connected to the ICD. A cardiac physiologist will test the pacing leads using a special ICD lead analyser to ensure best lead placement. The ICD generator will also have to be tested. To do this you will be sedated . Whilst under sedation a ventricular arrhythmia will be induced and terminated by the device. The test is essential to ensure correct device function and programming of the vital settings. Following this the wound is closed, using stiches, cleaned and dressed.

After the implant procedure

You will be taken to a day ward to recover from your procedure and allow time for the sedation to wear off. Once the sedation and anaesthetic has worn off your ICD incision may feel bruised or uncomfortable. If you feel pain, please alert the nursing staff who will be able to offer assistance.

After your recovery, you will be transferred to the cardiac ward where you will stay overnight. The next day you be will sent for an X-ray to confirm the position of the ICD leads. You will also have a pre-discharge ICD follow-up and will be prescribed a week’s course of antibiotics, which you must complete.

Returning to work after ICD implant

Most patients are able to return to work after a few weeks of rest however this is dependent on individuals. There are a few jobs that may be affected by having ICD implant. If these are applicable to you, please discuss this with your doctor.

• Arc Welding
• Working in areas where industrial magnets are used e.g. scrap metal yards
• Work with television, radio or radar transmission equipment
• Work in military installations
• Jobs involving carrying Hi-Fi or PA speakers
• Heavy load, cabs, mini-cabs drivers and other public carriers (The DVLA regulations may restrict your licence which may impact on your ability to work in these areas)

Leaving hospital

Before you are discharged from Hospital ask a member of staff to give you a copy of A patient’s guide: Living an ICD. It is a follow-on from this guide, which gives you information about: who to contact should you get a shock, ICD follow-ups, driving regulations, exercise and work, travelling and other related information.

What do I do when I receive a shock?

If one shock occurs and recovery is immediate, a call to the device clinic may be reassuring for the patient as well as the family. However, if one or more than one shock occur without rapid recovery, 911 emergency services should be called. If CPR and other lifesaving activities are needed, they should be started immediately.

How does it feel?

Fast pacing therapy may feel like a flutter or palpitation in the chest, or nothing at all. The shocks may feel like a sudden painful kick in the chest. It occurs in an instant and then is gone. If a blackout occurs, the shock may not be felt. Someone touching the patient may feel a small muscle jerk. It will not harm them.

How and when is the battery replaced?

The battery check at each visit will determine when the ICD should be replaced. The electronic circuitry as well as the battery are sealed inside the ICD. When replacement time arrives the lead(s) will be tested and then a new ICD is attached to the lead(s). Usually the original lead(s) are reused.