A pacemaker is a small electrical device that can be implanted if your heart has started to beat too slowly causing you to feel dizzy or have falls or blackouts. It can also sometimes be necessary if you have had a special procedure called a Catheter Ablation to prevent rapid palpitations in Atrial fibrillation (or very occassionally for Supraventricular tachycardia). Treatments for Atrial Fibrillation

In some people, despite the heart muscle and the coronary arteries being entirely normal, the electrical conduction system of the heart can fail. The chances of this happening increase as we get older. Worldwide more than 3 million people have pacemakers and currently the implant rate in the UK is about 300 per million of the population and is rather higher in most of the rest of Europe at 450 per million population.

The type of pacemaker that is required will depend on the underlying problem with the person's own conduction system, the underlying heart rhythm that they are in and how physically active they are.

In simple terms one or all of the following parts of the conduction system can fail:

To see a fuller description of the anatomy and normal function of the heart's conduction system visit The Normal Heart Rhythm

Sinus node

This is your own inbuilt 'pacemaker'. It is an area within the muscle of the right atrium which rhythmically discharges electricity which is then conducted through the muscle of the two atria (right and left) causing them to contract and push blood out of these chambers through their two respective valves (tricuspid and mitral) into the two main pumping chambers of the heart (the ventricles).

A-V node

This is a small collection of specialised tissue sitting between the atria and ventricles at the top of the intra-ventricular septum (the wall that separates the two ventricles). The electricity arriving here from the atria takes up to 0.2 seconds to travel through the node which allows time for the blood to get into the ventricles. The electricity travels out of the A-V node into the His-Purkinje fibres.

The His-Purkinje fibres

These fibres are similar to nerve tissue running through the muscles of the heart. The electricity travels down the fibres that then split into right and a left bundles (fascicles), running to the right and left ventricles respectively. The left bundle further splits into anterior and a posterior branches (bundles) which supply the front and back of this chamber respectively.

In this way electricity travels quickly down the fascicles to these three areas, then from there more slowly through the heart muscle causing the ventricles to contract simultaneously pushing blood out of the heart to flow through the lungs (from the right ventricle) and the around the body (from the left ventricle).

After a period of electrical recovery the cycle is repeated causing the next heart beat and so on.

This cycle of events is shown in the diagram below.

Development of artificial Pacemakers

Dual chamber pacemaker

The development of artificial pacemakers for patients is a relatively new technology. The first attempts to pace a patient was in 1957 using a large electrical device outside of the patient's body. In 1958 in Sweden the first implantable device was tried. This was still a very large piece of equipment and the wires had to be surgically attached to the outside of the heart.

It wasn't until 1962-3 that devices were developed that allowed the pacing wires (that delivered the electricity to the heart muscle) to be passed down the veins onto inside surface of the heart. Even at this stage the length that the devices lasted was poor due to poor battery technology but the switch from mercury batteries to lithium powered cells gave much greater device longevity and today pacemakers can often last up to twelve years.

Another progressive advance has been the reduction in size of implantable pacemakers over the years despite their very increased electrical sophistication. Shown is a photograph of a dual chamber pacemaker alongside a 50p coin to illustrate its dimensions.

More information on the differences between single and dual chamber pacemakers can be found by following the link to Frequently asked questions and information on pacemakers for cardiac resynchronisation in the section on heart failure Heart Failure.

Automated internal cardio-defibrillators (AICD's) also have pacing functions Heart attack/Myocardial infarction - see section on late (ventricular) arrhythmias.

Devices and Driving

In the UK there are regulations laid down by the DVLA for driving following the insertion of pacemakers and AICD's as well as after a catheter ablation. These can be found in full at the DVLA web site. Here I give a short summary of the main points. The rules are different for those holding a professional licence (Group 2) than those with a car or motorcycle licence (Group 1).

Catheter Ablation

Following a catheter ablation Group 1 holders should not drive for two days. For Group 2 holders, if they had disabling symptoms before the procedure, they cannot drive for six weeks. However, if they did not have disabling symptoms then they can resume after two weeks.


Following the insertion of a pacemaker Group 1 holders cannot drive for one week and Group 2 holders for six weeks. (Doctors would recommend that Group 1 holders did not return to driving for several weeks to minimise the chances of pacemaker wire displacement and healing of the wound over the pacemaker).


For Group 2 licence holders who require an AICD, then unfortunately they are permanently disqualified from regaining a Group 2 licence. For group 1 licences the regulations are rather complicated. If the AICD has been implanted because of disabling symptoms, then they cannot drive for six months or for six months after any shock delivery. They also cannot drive for a month after any box (generator) change. In patients in whom the AICD has been implanted for asymptomatic ventricular tachycardia then they cannot drive for one month. These patients must also have an ejection fraction of 35% or above (see heart failure section Heart Failure) and not have any fast VT on electrophysiological testing.

For patients who have had the AICD inserted because they are thought to be at high risk but have not been shown to have any ventricular arrhythmias then they can resume driving after one month. DVLA

Implanting a Pacemaker

Frequently asked questions

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