The first pacemakers to be developed were used to treat patients with heart rhythms that caused their hearts to go too slowly. In the last ten – fifteen years more advanced devices have been developed and used but as yet they are only required by a minority of patients requiring treatment with a pacemaker.
Pacemakers for slow heart rhythms
Patients can develop problems with the "electrical wiring" of the heart that causes their heart rate to fall. The normal resting heart rate is usually about 60 – 80 beats per minute at rest. During the night when you are asleep the heart rate can naturally fall to about 40 bests per minute without problems.
During the day if your heart beat falls to below about 35 beats per minute then you may feel as though you are about to faint or indeed faint. These slow heart rhythms may only happen from time to time so it can take the doctor a while to reach the diagnosis.
If the problem turns out to be a slow heart rhythm then you may be recommended to have a pacemaker implanted. A pacemaker is a small electronic device. It is put into a small pouch below the collar bone. The operation is quite minor and is done under local anaesthetic and some sedation. The pacemaker box is connected to the heart by one or two wires depending on the type of pacemaker used. The wires are put into a vein and positioned in the heart using an x-ray camera. Once the wires are in the right place they are connected to the pacemaker box which is then put into the pouch and the skin is sown up burying the pacemaker.
The pacemaker monitors the heart rate all the time. If the rate falls below a preset amount then the pacemaker will give a small electrical shock to drive the heart. This shock is too small to be felt by the patient. Once the heart rate has risen above the preset amount the pacemaker goes back to monitoring the heart until the rate falls again. Some patients use the pacemaker for only a few minutes per day others use it most of the time.
The settings of the pacemaker can be adjusted using a small device about the size of a computer mouse on the skin over the pacemaker. Pacemakers are battery driven devices so they will eventually require changing. In Great Britain patients have their pace maker checked once or twice a year so there is plenty of warning of when the pacemaker needs changing. In many cases the pacemaker will last 7 – 10 years before needing to be changed.
Other sorts of pacemakers
In addition to pacemakers used to treat slow heart rates there are a range of more complicated devices used to treat patients with some forms of heart disease. Some forms of fast heart rhythm may be treated with a defibrillator and there are other devices used to improve the efficiency of some patients with heart failure – cardiac resynchronisation therapy. Some devices can even combine both the defibrillator and resynchronisation functions.