Electromagnetic Compatibility of Cardiac Pacemakers

Recent tests conducted by personnel of the USAF School of Aerospace Medicine demonstrate a wide range of electromagnetic radiation susceptibility among different types and models of cardiac pacemakers. Pacemakers made by seven different manufacturers and representing the vast majority of implantable devices currently being marketed were tested. Many of the tests were performed on pacemakers implanted in large canines having surgically induced atrioventricular heart blocks. Eleven discrete frequencies between 10 MHz and 3050 MHz, pulse repetition rates from 0.5 to 360 Hz, pulse durations from 0.5 to 5 msec, and E-field.strengths up to 800 volts/meter were used in this series of tests. Field intensities as low as a few volts per meter caused complete inhibition (cutoff of pacemaker activity) of some pacemakers, whereas others in the same tests were essentially unaffected in fields 100 times higher. These test results, plus data from other similar studies, indicate a need for further improving of such medical prosthetic devices in order to be compatible with the ever-increasing electromagnetic radiation background found in many major metropolitan areas today.