Experimental and numeric investigation about electromagnetic interference between implantable cardiac pacemaker and...

The present contribute describes the investigation about the implantable pacemaker (PM) immunity against high level magnetic interfering fields at 50 Hz that a pacemaker wearer could find in his working environment. To this purpose, a test bench has been set up based on a Helmholtz coil for producing extremely low frequency (ELF) magnetic fields and a heart simulator rightly fed by electric signals that simulate atrium and ventricle signals. A widely diffused PM has been tested, under different operation modes and configurations, for both continuous interfering waves (CW) and variously pulsed interfering waves (PW). Pertaining the obtained results, high levels of CW field, only in unipolar mode, produce a behaviour called 'asynchronous mode' (not dangerous). For PW fields, under particular and rare conditions, the complete inhibition occurred (the most dangerous effect for PM wearer). In order to validate experimental results, a numerical 3-D model has been developed to simulate the whole bench system formed by Helmholtz coil, human trunk, pacemaker case and its electric leads. In this model the electromagnetic problem is solved by reconstructing the inhomogeneous bench system associating the relative values of conductivity to each cubic cell in which the whole system is discretized. Application of Maxwell's equations in their integral form has allowed to obtain a 3-D electrical network, whose solution gives the current density distribution inside the heart simulator.