Forschungsgemeinschaft Funk e.V.

Edition Wissenschaft

Back to overview

Edition No. 5 March 1996
Electromagnetic Immunity of Cardiac Pacemakers in the Frequency Range 30 kHz to 2.5 GHz

Dr.-Ing. Hans-Jürgen Meckelburg, Dipl.-Ing. Klaus Jahre, Dr.-Ing. Klaus Matkey, CETECOM GmbH, Im Teelbruch 122, 45219 Essen

This study deals with the electromagnetic immunity of cardiac pacemakers in the frequency range 30 kHz to 2.5 GHz. Basically, a pacemaker is made up of electronic circuits for stimulation and analysis and a battery with a service life of several years. Stimulating electrical pulses are applied to the heart via a lead to replace the missing stimulation of the heart. The heart’s own stimulation is analyzed via the pacemaker lead.

The pacemaker electrode implanted in the body acts as an antenna in presence of electromagnetic fields. Interference voltage and high current density at the electrode tip can endanger the patient.

From the functional point of view, pacemakers are particularly sensitive to pulse signals, especially in the frequency range of the heart beat. The interference caused can disturb the pacemakers in two completely different ways:

  1. the socalled ”defined spurious operation”: The pacemaker cannot distinguish the natural heart signals from the coupled interfering signals. However, it can recognize interfering signals as such. Therefore, it proceeds to stimulate the heart at a fixed frequency.
  2. the socalled ”undefined spurious operation”: The pacemaker stimulation can fail or take place in an uncontrolled and unforeseeable way, i.e. risks for the pacemaker patient in this type of operation cannot be excluded.

Spurious operation is distinguished from normal operation where the pacemaker performs its intended functions without any problems.

There is at present no legally binding standard in which the requirements for the electromagnetic immunity of pacemakers are defined. Of course, requirements are laid down in the European standard EN 50 061 A1 but they are very controversial among the experts and they have not been used until now by the European Union to fulfil the essential requirements. Moreover, the requirements above 30 MHz have not been defined.

Test Setup and Method

The objective of this study was to make conclusions on possible risks for patients based on the results obtained on the electromagnetic susceptibility of pacemakers. For frequencies above 30 MHz, new test methods and requirements had to be developed. In this connection, the types of modulation and transmitting powers which are typical within the relevant frequency ranges have been taken into account. This applies to radio and television transmitters as well as to the new digital radiocommunication systems (GSM 900 / DCS 1800).

The following steps were necessary to carry out the study:

  • Development of a test and evaluation system:

A model had to be developed to capture the coupling procedure of the high-frequency field into the pacemaker system. A suitable test and evaluation method could thus be drawn up. Representative interfering signals were selected and further test limitations were defined.

  • Determination of the number of types of pacemakers implanted:

560 different types of pacemakers registered in the year statistics of the HSM central register were first examined. Since different type descriptions were often indicated for the same type in the register index, 95 different types were finally retained for the investigation. They cover more than 80% of the patients.

  • Acquisition of pacemakers:

Models were purchased from manufacturers or acquired.

  • Measurement of the electromagnetic susceptibility:

Measurements were performed with three test methods at different frequency ranges (30 kHz to 100 MHz, 100 to 850 MHz and 850 MHz to 2.5 GHz).

  • Evaluation of the electromagnetic susceptibility:

Graphical representation of the percentage of the implanted pacemakers disturbed at a particular interference level.

  • Weighting with frequency of implantations:

The immunity to interference of the different types of pacemakers was compared with the frequency of their implantation. This enabled the percentage of patients to be determined who were affected by the high-frequency electromagnetic fields.

Results and Evaluation

A comparison of the results shows that pacemakers resistant to interference were not implanted more often than those which are less resistant to interference. This means that immunity to interference has not been up to now a selection criterion for the implantation of pacemakers.

The reason for this may be that there has been no binding requirement for the immunity to interference of pacemakers. Since there are no requirements for pacemakers, it is obvious that EMS is still left to chance. However, immunity to interference has been improved up to 50 MHz if one compares this study with the RWTÜV study of 1989.

A high percentage of pacemaker types operates without any problems in the relevant interference fields examined. However, there are some types that are affected in each frequency range.

In the 100-MHz range, TV transmitters have proven to be unproblematic. Of course, this is only true if the transmitters comply with the limit values for personal protection.

In the mobile radio range (C and D network), a small number of types can be affected. In the C network (450 MHz), this can only arise on dialling. In the D network (900 MHz), impairment is observed in the socalled DTX mode. For this, a voice link has to be established in the listening mode. The two problems can be solved in the short term by rules of behaviour (warning signs).

In the E network, no influence is to be expected, since the maximum transmitting power is only 1 W and the coupled interference decreases with increasing frequency.


All the problems revealed during this investigation can be technically solved. There are presently 200,000 pacemakers implanted. Just replacing them is not that easy. For this reason, rules of behaviour (warning signs) is the only protective measure which is effective in the short term. These warning signs should be distributed by the pacemaker manufacturers and also by the manufacturers of radio equipment which can be a possible source of interference.

A general recommendation: The pacemaker patient should not carry the switched-on handy in the breast pocket. To operate the unit, it should be held at a distance of more than 20 cm from the breast (pacemaker). There is no risk during phoning (handy on the ear).

The results of this study (test method and limit values) are suitable for the standardization of pacemakers.

In this study, no bipolar pacemaker was examined, since the electromagnetic susceptibility of such units is lower due to inherent design, i.e. immunity is higher. Therefore, measurements would not reveal any new findings.

Back to overview