Pacemakers

A pacemaker is an electrical device that is used to correct and regulate an abnormal heart rhythm. When necessary, a pacemaker will send out electrical signals to stimulate the hearts chambers to contract and relax in a regular way. In effect, pacemakers artificially take over the role of the heart's natural pacemaker. They can be set to work only if needed (on demand) or all the time (fixed rate).

Nowadays pacemakers are comfortable and reliable. Most people live a normal life after they have had a pacemaker fitted.

Why do I need a pacemaker?

If the electrical activity of your heart is upset your heart may be unable to pump sufficient blood around your body. This can cause symptoms to occur. You may be tired and lethargic and have an increased risk of falls and blackouts. Depending on your symptoms your heart specialist may suggest fitting a pacemaker device.

Pacemakers are mainly used:

• To deal with your heart going too slowly.
• When your heart's electrical activity does not join up, so it can not deliver an adequate rhythm (called heart block).
• When your heart is periodically running too fast, it may be necessary to take drugs that will slow your heart down. However, during the times when it is not going too fast, the drugs will still have this effect resulting in too slow a heart rate. A pacemaker would ensure that this low rate was corrected.
• If your old heart rhythm is wiped out altogether for whatever reason, e.g. ablation therapy (used for some arrhythmias). A pacemaker would replace the rhythm and ensure a regular heart rate is restored.

How does a pacemaker work?

A pacemaker consists of a 'box' and pacing wires:

• The pacemaker box: a lithium battery, the pulse generator and a tiny computer, are safely encased in a small titanium box to protect them within the body. It is about the size of a small matchbox and weighs about 20-50g (1-2 oz).
• The battery will be tested periodically and is replaced long before it runs out. The box has to be removed to replace the battery.
• The tiny computer can be programmed according to your individual needs. If your condition changes then alterations to the programme can be made. This can be done, without another operation, by electromagnetic signals from an external computer.
• The pacing wire: electrodes are attached to the end of one, two or more pacing wires (leads) which are placed inside the chamber(s) of your heart depending on what type of arrhythmia you have. From there information about your heart rate and rhythm is sent to the computer which recognises if impulses to the chambers are needed 'on demand' or if 'fixed rate' checks that the rate is correct. Impulses are delivered by the electrodes, according to the discharge rate the doctor has set for you.

There is a special type of pacemaker called an implantable cardioverter defibrillator (or 'ICD') which can deliver much stronger electrical impulses to reverse a dangerous heart rhythm.

• Information on living with a pacemaker is available here.

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