Effects of electromagnetic fields on pacemakers and defibrillators

Signals with low frequencies can directly intersperse magnetic fields into the pacemaker housing. Additionally the pacemaker electrode can act as an antenna that captures disturbing electromagnetic signals with higher frequencies and carry them into the pacemaker.

The exposure of a pacemaker to electromagnetic radiation can

• produce currents from the electrode into the cardium and therefore ventricular fibrillation or tissue damage by local heating
• induce electric voltage into the electrode that influences the pacemaker's control of heart signals (ECG)
• induce electric voltage into the electrode that damages the pacemaker
• accidentally activate or damage magnetic controllers of the pacemaker
• cause the pacemaker to switch into the safety mode

The draft standard DIN VDE 0848-3-1 is the basis

Hazards depend on the electrode's orientation but also on the properties of the electromagnetic field. The frequency and signal form (modulation type) of the field have a special impact. E.g. pacemakers respond exceptionally critical to modulation frequencies that are similar to the heart's own rhythm.

The draft standard DIN VDE 0848-3-1 ("Safety in electric, magnetic, and electromagnetic fields" dated May 2002) specifies typical thresholds at different frequencies for variably modulated fields. Since the thresholds depend on the circuitry of the device and vary for different devices the thresholds have been defined in that way, that more than 95% of all pacemakers being implanted in the time period between 1995 and 1999 are not affected at field strengths below the given values.

The draft standard recommends to mark all public areas where a hazard for pacemaker patients might occur with warning signs. However, the implementation of this measure has proved to be not practicable. It is for example almost impossible to provide all power transmission lines over kilometres with warning signs.

That is why the Cardioman follows another approach: It gives every patient the possibility to identify and avoid dangerous areas by himself or herself. It additionally enables to value the hazards of everyday electric appliances.

Guideline of the International Commission on Non-Ionizing Radiation Protection

The ICNIRP (International Commission on Non-Ionizing Radiation Protection) works out and regularly publishs guidelines for different radiation modes which are based on the accepted state of the scienctific and technical knowledge. A respective guideline also exists for electric, magnetic, and electromagnetic fields (see ICNIRP guideline). It includes very interesting information about the interaction of such fields with the human body.