Company physicians are more and more confronted with the decision whether people with active electronic implants (like cardiac pacemakers) are allowed to work at workplaces with low-frequency magnetic and electric field exposure. In recent years cardiac pacemakers with bipolar leads become more popular because they are less sensitive to low-frequency magnetic fields than pacemakers with unipolar leads. In order to quantify the benefit of bipolar pacemakers the present project was initiated.The purpose of the project is to significantly improve the health care and the flexibility of implant carriers. This report was created by IMST GmbH, FH Dortmund and HTWK Leipzig.

The IMST GmbH and the University of Applied Sciences Dortmund have developed a numerical coupling model for bipolar leads taking into account a realistic position of the implant in the human body and a realistic model of the exposure scenario. The influence of different parameters like position of the cardiac pacemaker leads in the numerical body model, the use of simplified body models, tissue variations and grounding effects of the body on the bipolar voltage are investigated. The numerical results are verified by measurements and compared to the existing literature.

In the frame of a master thesis the University of Leipzig has concerned with analytical models and measurements to determine bipolar voltages. Two different methods were developed to measure the induced bipolar voltage for magnetic field exposure. Conducted measurements were carried out to investigate the impact of the electric tissue conductivity on the bipolar voltage. Based on the measurement results equivalent circuits of bipolar electrodes configurations were developed. These circuits include the solid-liquid interface at the tip of bipolar electrodes configurations and the common to differential mode conversion.

Please download the complete report "Modeling of bipolar electrodes configurations of a cardiac pacemaker (10 Hz to 1 MHz)" (in German only).