An implantable loop recorder may be the best way of determining if the cause of a person's collapses is due to a heart rhythm disturbance if the collapses occur only very rarely. In these circumstances external loop recorders cannot be worn long enough to have a realistic chance of recording the event and the patient is unlikely to be be concious at the time of the event and therefore cannot use a cardiomemo device.
A device is shown in the photograph above alongside a 50p piece for scale.
This is inserted under the skin in a similar fashion to the insertion of a pacemaker. The operation is carried out under local anaesthetic and a small cut in the skin about 1.5cm is made a then a space under the skin and subcutaneous fat is made for the device. Since there are no wires it is a much simpler operation than for a whole pacemaker system and usually takes less than ten minutes.
Once in, the device records the heart rhythm continuously in a similar fashion to a black box recorder on an aeroplane flight deck. That is, after a couple of minutes recording it starts to save information over the beginning of the stored recording. If the heart rate goes above or below preset levels these recording are automatically stored in the device and can be later downloaded and analysed. Also the patient has a small remote control so that if they have any symptoms they can activate the device to store the heart tracing at that time as well.
The battery life of the device is about two years so any cardiac rhythm problems occuring in the next 24 months will be recorded.
Once the diagnosis has been made, or the battery life of the device exceded, then it is removed by a simple operation again carried out under local anaesthetic.