Modelling of High-frequency Electromagnetic Interference in Human Body with Pacemaker Implanted During Transient Process in Power Network

In recent years, implantable cardiac pacemakers are being increasingly used as lifesavers for the patients with cardiovascular diseases. Even though a pacemaker is generally designed to have excellent electromagnetic shielding capability, clinic reports have indicated that cardiac pacemaker may suffer electromagnetic interference (EMI) from various external fields. However, at present the research is mainly on the EMI of implanted pacemaker by medical radiations or electromagnetic sources at power line frequencies (50 or 60 Hz). For the cases where the high-frequency electromagnetic field takes place, the exact effect of such strong electromagnetic fields on implanted pacemaker should be clarified. In this paper, the electromagnetic interference in a simulated model of human body by high frequency pulsed current source was studied. The human body model is made by a dual-chamber pacemaker connected to a pork heart which is immersed in 0.9% saline solution. Microsecond pulsed currents with amplitude ranging from 1 kA to 5 kA were produced in a transmission line with diameter of 8 mm to simulate transient electromagnetic processes occurred in nearby power network of the human body model. A self-designed probe with sampling rate up to 500 kHz and voltage measuring amplitude of ± 3 V is used for electromagnetic field monitoring in the human body model. Experimental results indicate that during transient processes, EMI with similar magnitude of output pulses of pacemaker exists. The severity of EMI increases with the increase of magnitude of current. The electrocardiogram recorded by the probe indicated that this type of EMI may block the output of the pacemaker, and cause dizziness, nausea or even faint in the human body due to insufficient cardiac rate.