PACE

What is a Pacemaker?

Posted 21 January 2010 in Posts / Articles

What is a Pacemaker?

What is a pacemaker?
A pacemaker is a small, sealed metal and plastic device (pacemaker box), which contains a battery and electronic circuits. The device is connected to your heart by one or more wires (called leads). These leads are passed along a blood vessel to your heart and the pacemaker box is usually implanted under the skin in your upper chest, near your collarbone. The pacemaker monitors your heart and produce electrical impulses to treat abnormal heart rhythms.

Pacemakers are largely used to treat slow heart rhythms (bradycardia), but are also used to treat some fast heart rhythms that come from the top chambers of the heart (the atria). A new type of pacemaker, the biventricular pacemaker or cardiac resynchronization therapy, is increasingly being used to treat patients with heart failure; this is not suitable for all but can be discussed with your doctor. Pacemakers may be single (one lead), dual (two leads) or triple (three leads) chamber and you will have the one appropriate for your underlying problem.

Why do I need a pacemaker?
If your doctor has suggested that you have a pacemaker fitted it is because you have an abnormality in the electrical conduction system of your heart. To help you understand this, it may be useful for you to know how the electrical conduction system in your heart works normally.
                         
The heart and normal electrical conduction
The heart is a muscle; its function is to pump blood and oxygen around your body to all of your vital organs. A normal healthy heart usually beats in a regular fashion at around 50 to 100 times a minute. It has four chambers, two at the top (the right and left atria) and two at the bottom (the right and left ventricles). The heart also has an electrical system (rather like the wiring system in your house or car), which sends impulses (beats), through the heart causing it to contract and pump blood around the body.

Each normal heartbeat begins in the natural pacemaker of the heart (the sino-atrial or SA node), which lies at the top of the right atrium. It then travels across the two top chambers and down through a small junction box (the atria-ventricular or AV node), which lies between the upper and lower chambers. It then spreads rapidly through a special conducting system through the ventricles and then across the bottom chambers causing the heart to contract and pump. Sometimes the electrical system in your heart does not work as well as it should. This can cause the heart to beat too slowly, too quickly or irregularly. A pacemaker can treat some of these abnormal heart rhythms.

There are several different common conditions, which cause the heart to beat abnormally:

Complete or Intermittent Heart Block
This accounts for about 60% of patients who have pacemakers. This is a condition where the AV node breaks down and does not transmit the electrical pulse from the top to the bottom of the heart. This is called heart-block and may be complete or partial. When this happens the heart usually goes very slowly and you may have symptoms of dizziness or blackouts. A pacemaker is required to restore a normal heart rate and bypass the “block.” This is most commonly due to the conduction system “wearing out with age”, but can also occur as a congenital (in-born) problem.

Sick Sinus Syndrome
This is a condition where the natural pacemaker does not function properly and results in your heart going either too slowly or too fast or a combination of both. An implanted pacemaker is used to support the slow heart rate and medicine is usually given to control the fast heart rhythms.  Pacemakers are also used following a procedure called ‘catheter ablation’ that involves applying ‘radiofrequency’ (similar to a microwave) energy to the AV node which destroys the cells in this area. This means that the heartbeats can no longer travel from the top to the bottom of the heart and a pacemaker is then used to deliver electrical impulses to the heart.

Heart Failure
Some people who experience ‘heart failure’ (when the heart does not pump as well as it should) can benefit from having a particular type of pacemaker, which is known as a ‘biventricular pacemaker’ or ‘cardiac resynchronisation therapy’. If you have heart failure, this therapy may improve some of your symptoms. However, not all people who experience heart failure will benefit from this treatment and careful assessment is needed before this type of pacemaker is implanted. There are many different types of pacemaker available to suit specific heart rhythm problems. In order to help decide which one is right for you, you may need to have some tests or investigations before the decision to have a pacemaker fitted is made.

 

How is the pacemaker implanted?
On the day of your procedure, you will be taken to the cardiac pacing theatre or catheter lab. Once you are in the pacing theatre, a nurse will check your details again and you will be asked to lie on a trolley or narrow operating table. The procedure is not usually performed under a general anaesthetic, but you may be given sedation, which will make you relaxed and sleepy. Before the procedure starts, the doctor will clean the skin with some antiseptic solution and inject some local anaesthetic under the skin just below your collarbone (usually on the left side as most people are right handed, however if you are left handed your doctor may be able to implant the device on the right side). This will numb the area and allow the doctor to pass a small lead or electrode through a vein into your heart. You may have one, two or three leads inserted depending on what type of pacemaker you need. The lead(s) are then connected to the pacemaker box. This will usually be placed under the skin on your chest wall. The area will then be stitched with dissolvable or non-dissolvable stitches. The whole procedure should take approximately 60 to 90 minutes.

Are there any risks associated with the procedure?
There are some small risks associated with having a pacemaker fitted. Generally the most common risks are; • A small risk of infection, bleeding and bruising to the pacemaker site • A small risk of lead displacement – the pacemaker lead can move and would then need to be repositioned • A small risk of perforation of the lung during the procedure – this is often detected on the chest X ray that is performed following the pacemaker implant and can sometimes rectify itself without treatment. Very occasionally a small drain may need to be inserted through your side into your lung (in the space between your ribs) this is a simple procedure and the drain will be removed prior to your discharge home.

What happens after the pacemaker is fitted?
After the procedure, you will be taken back to the ward. You will be asked to lie in bed for a couple of hours then you can get up and eat and drink. Your heart rhythm may be monitored for a while to make sure that the pacemaker is doing its job, so you may be attached to an ECG monitoring device with some stickers and leads. As the wound can feel quite bruised and sore, especially for the first day or two, it is recommended that you have regular painkillers. It is very important that you tell your nurse immediately if you have any pain or discomfort at all. You may also be given some antibiotics to take before and after the procedure to minimize the risk of infection.

The wound should be kept clean and dry until it has fully healed, although it is fine to have a bath or shower after the first three or four days. Ask your nurse for a protective dressing so that you can bathe without wetting the wound. Report any wound problems to your nurse. You will probably be allowed to go home the same or the next day provided your pacemaker is checked, there are no complications and your doctor assesses it is safe.

Your pacemaker will be checked before you go home. This check may involve the use of a special programmer that can look at the device settings and make sure the pacemaker is working properly, or a simple magnet check and an ECG will be sufficient. This check takes about 15 minutes. You will also have a chest x-ray to check lead positions and make sure all is well following the implant procedure. You will be given a pacemaker identity card, which has details of the make and model of your pacemaker. You should always carry this card with you. If you require any further treatment in the future it is important that you show this card to the health care professionals treating you.

Arm movements
Extra tissue will grow around the lead(s) in your hear t after a few weeks, which will prevent the wire(s) moving out of place. Try to avoid lifting the arm on the same side as the pacemaker above shoulder level or stretching it out behind your back until you have had your first outpatient check. Once you have had your first pacemaker clinic check you will be able to return to normal activity.


Wound site
Your wound site should take about six weeks to fully heal. Try to avoid wearing tight clothing over the wound until it has healed completely to avoid excess rubbing over the area. If you notice any redness, soreness or swelling of the area, or any signs of bleeding or oozing from the wound, report this immediately to your GP as these may be a sign of wound infection. You will probably be able to feel the pacemaker box under your skin as well as other lumps close by. These are the leads that are attached to the box, curled up beside the box under the skin. It is extremely important that you don’t try to move the box or leads, but please let someone know if they continue to bother you.

Will I feel the treatment from the pacemaker?
The device will be programmed to the best settings for you. This will be done before you leave hospital, but the settings can be modified during your follow up appointments in the clinic as and when necessary. You should not be aware of the pacemaker working but occasionally people are conscious of their heart beating faster, particularly if you had a very slow heart rhythm before the pacemaker was implanted. The pacemaker will not usually stop the heart from speeding up so if you had fast palpitations before then they may continue. If this occurs the palpitations are usually treated by medicine. The pacemaker will be set to enable your own heart to work as much as possible on its own and will only come in if your heart rhythm slows down to a certain level. It works on “demand”.

Will I be able to stop my tablets after I have my pacemaker implanted?
This will depend on why you had the pacemaker implanted and your cardiologist will advise you what to do.
 

Safety Issues
Can I still drive after I have my pacemaker implanted?
It is very important that you discuss this with your nurse, physiologist or doctor at your pacemaker centre who will explain this in more detail.

Can I exercise after I have my pacemaker fitted?
A certain level of exercise is needed to keep your heart healthy. You can take part in most sports but it is advisable to avoid contact sports to minimize the risk of damaging your pacemaker. Following your initial recovery, normally about 4 weeks, it is recommended that you try to increase your level of activity if possible. Please talk to the doctors, nurses or physiologists.

Is there any equipment that can affect my pacemaker?
Electromagnetic interference will not damage your pacemaker but may temporarily interfere with its settings whilst you are in contact with it. Most mechanical and electrical devices that you use in your normal daily activities will not affect your pacemaker. Household equipment such as ordinary radios, fridges, cookers, remote controls, televisions, electric razors, computers and microwaves etc. will not affect your pacemaker as long as they are in good working order.

It is best to check with your Pacemaker Clinic for advice. If you feel dizzy or experience palpitations whilst using an electrical appliance, you should move away from the appliance and phone the physiologist, specialist nurse or doctor at the pacemaker clinic for advice.
 
Magnets
Do not carry magnets or place a magnet over your chest. Avoid carrying stereo or hi-fi speakers as they contain strong magnets that can interfere with your pacemaker.

Shop doorway security systems
It is advised that you walk through shop doorway security systems at a normal pace and not to wait around in this area.

Medical equipment / other hospital treatments
Most equipment used by your hospital or GP surgery will not cause any problems to your pacemaker. But it is advised that you let medical and dental staff know that you have a pacemaker. Take your ID card with you when you go to hospital. You may also contact your implanting centre for advice before any investigations or operations that are not associated with your pacemaker.

It is safe for you to have X-rays, CT scans and mammograms.
You should however avoid magnetic resonance imaging (MRI) machines. Some electrical nerve and muscle stimulators (TENS units) may cause interference with pacemakers but this depends on where they are being applied, and, if any of these treatments are suggested to you then your pacemaker clinic should be contacted for advice.
 

Travel
You can safely travel abroad with your pacemaker, but are advised to show the security staff your identification card. Walk through the metal detector archway if asked to do so, but the metal casing of the device may set off the airport security alarm. The detector will not cause any harm to your pacemaker provided you walk briskly through the arch.

Arc welding
Generally, this should be avoided but can be performed under special circumstances.

Mobile phones
Mobile phones can affect the pacemaker if held within 6 inches of the device. It is recommended that you do not keep a mobile phone in a coat or shirt pocket over the pacemaker. Keep the handset more than 6 inches away from the pacemaker; ideally hold the phone over the ear on the opposite side to the device. Avoid direct contact with the antenna whilst busy with a call.

Pacemaker Clinic Visits
Your pacemaker should be checked regularly. You will be seen at least once a year or more often if necessary. During each clinic visit, the physiologist or nurse will examine your pacemaker using a special programmer. This machine allows us to examine the settings and the battery life of your device. Special measurements are also done to assess the state of the leads that connect the pacemaker to your heart. If your condition has altered, changes may be made to the pacemaker settings using the special programmer. All information is stored in your records. Your wound will be checked and you may have other tests done. Please ask any questions and you may also see the consultant cardiologist or their registrar.

Changing the pacemaker
Normally a pacemaker battery lasts between six and ten years. Your battery will be checked at every visit to the pacemaker clinic and staff at the clinic will be able to predict when you need a new pacemaker box and arrange for you to be admitted at a convenient time for you. Don’t worry! It will not be allowed to completely run down. In order to have the box changed, you will need to be admitted to hospital. The procedure is similar to having your first pacemaker fitted, but it will not usually involve having new leads put in.