Pacemaker testing
Cardiac arrhythmia, where the heartbeat is too slow (bradykardia), can be congenital or occur after inflammation of the heart muscle or heart surgery. Surgically implanted pacemakers consist of a battery and the electrodes, which are attached in or on the heart. After implantation, the devices must be checked regularly - usually every 6 months. This pacemaker test is completely painless and is carried out using radio waves simply by placing a special magnet on the pacemaker battery.
Modern pacemakers also have a memory function so that the remaining battery life can be determined. It is also possible to see how often the pacemaker has been active. Rhythm disturbances or electrode problems are recognised by the pacemaker device so that a kind of long-term ECG is available at the same time. The setting can be adjusted to the patient's needs at each pacemaker test.
Patients who have an abnormally fast heartbeat (ventricular tachycardia, ventricular fibrillation) are given a special type of pacemaker called an ICD (internal cardioverter defibrillator). In principle, the check is carried out in the same way as with a regular pacemaker. In addition, the ICD is programmed to treat a life-threatening cardiac arrhythmia with an electric shock. As an ICD is only very rarely necessary in children, we will discuss this briefly later on this page.
Perception
The pacemaker is programmed in such a way that the patient's own heart action always takes priority and the pacemaker only stimulates the heart if the patient's own heartbeat is insufficient. How well the patient's own heart action is perceived is tested by determining the perception threshold (sensing), whereby the pacemaker frequency is reduced to a low heart rate during the test. The sensing threshold is then programmed in such a way that there should be no simultaneous self-action and pacemaker stimulation, as this could otherwise trigger arrhythmia.
Stimulation threshold
After testing perception, the minimum energy requirement required to stimulate the heart (stimulation threshold) is tested. For this purpose, the basic frequency of the pacemaker is now set above the natural frequency of the heart so that permanent stimulation of the heart by the pacemaker is guaranteed. The energy with which the pacemaker stimulates the respective ventricle via the electrode is then slowly reduced to the point at which no further cardiac action can be triggered. The value that is still just sufficient is known as the stimulation threshold. The set energy output from the pacemaker should always be at least twice the value of the stimulation threshold. The current level (amplitude in V) can be increased or the duration of the current output (pulse duration in ms) can be extended. Many devices also have an algorithm with which the pacemaker repeatedly measures these values itself and readjusts the respective values. On the one hand, this means increased safety, as the device recognises changes to its own stimulation or perception threshold, but on the other hand it can also save energy and battery power.
Optimisation of the pacemaker
The programming of the pacemaker is customised to the patient's needs. In particular, the times between atrial and ventricular stimulation (AV conduction) are optimised under cardiac ultrasound control so that the pacemaker mimics the natural sequence of contraction of the atrium and ventricle (sequential stimulation) as closely as possible.
Depending on the underlying disease and the underlying rhythm problem, as well as the patient's body size and growth, very different types of pacemaker therapy are possible and necessary in some cases. This means that, in addition to the general "battery change", electrode revisions, replacements or "upgrades" to more complex devices become possible or necessary with age.
X-ray image
As the electrodes become too short over time as the child patient grows, X-rays must be taken from time to time to check whether the electrode length is still sufficient. If this is necessary, an attempt can first be made to reposition the electrode in a minor surgical procedure. If this is not successful, the electrode is removed and replaced with a new one.
Pacemaker card
At the end of each pacemaker test, the current status of the pacemaker data, the heart function and the upcoming further examinations are explained in detail. Patients receive a computer printout with the newly programmed data. These printouts supplement the pacemaker card that every patient receives after implantation. This should be carried with you, especially when travelling, as it also contains the telephone number of the centre providing care so that you can be contacted immediately in the event of any problems.
Pacemaker - rules of behaviour
Pacemakers are high-tech electronic devices that can be interfered with by other electronic devices. For this reason, our patients receive a booklet when they are first implanted, in which the most important interference possibilities are described. The most frequently asked questions are listed here:
Pacemakers and mobile phones
Most modern mobile phones do not interfere with the pacemaker, but it is advisable to bring your own mobile phone to the pacemaker outpatient clinic so that we can check whether there is any interaction. As a general rule, the mobile phone should be held at the opposite ear to the implantation site when making calls.
Pacemakers and electronic children's toys
Most electronic children's toys do not interfere with the pacemaker. In individual cases, however, you should ask your paediatric cardiologist.
Pacemakers and airport security checks
At the airport security checkpoint, you must declare that your child is wearing a pacemaker. You will not be allowed to pass through the security barrier, but will be checked by the security staff by scanning.
Pacemaker and occupation
There are some professions that are not suitable for young people and adults with pacemakers. For example, welding work is unfavourable as the pacemaker could be affected.
Pacemakers and anti-theft devices
Anti-theft devices in large department stores contain strong magnets and can very rarely lead to the pacemaker being reprogrammed. It is therefore recommended to pass quickly through the anti-theft devices, which are usually installed in the exit area of large department stores.
