Interference voltage measurement and analysis of cardiac implants exposed to electric fields at extremely low frequency.

Objective.The possibility of interference by electromagnetic fields in the workplaces with cardiac implants is a concern for both individuals and employers. This article presents an analysis of the interference to which cardiac implants are subjected under high-intensity electric field at the power frequency.Approach.Evaluations of interference were conducted by studying the induced voltages at the device input in the real case study and the substitute study, and establishing an association between them with the equivalence factorF. A funnel-shaped phantom, designed forin vitrotesting and representing the electrical characteristics of the locations where cardiac implants are installed, was used in the substitute study. A measuring system was implemented to measure the induced voltage at the device input under high intensity electric fields.Main results.The induced voltages obtained in the experimental measurements align with the findings of the numerical study in the phantom. By applying the equivalence factors derived between the real case study and the substitute study (2.39 for unipolar sensing; 3.64 for bipolar sensing), the induced voltages on the cardiac implants can be determined for the real case using the substitute experimental set-up.Significance.The interference voltages on the cardiac implants under electric field exposures at low frequency were experimentally measured with detailed description. The findings provide evidence for an analysis method to systematically study the electromagnetic interference on the cardiac implants at low frequency.

Interference thresholds for active implantable cardiovascular devices in occupational low-frequency electric and magnetic fields: a numerical and in vitro study.

In light of concerns regarding the occupational safety and health of workers wearing active implantable medical devices (AIMDs), this study aims to investigate the potential risks of electromagnetic interference (EMI) between AIMDs and low-frequency 50/60 Hz electromagnetic fields (EMFs) in the workplace. A total of 58 AIMDs, consisting of pacemakers (PMs) and implantable cardiac defibrillators (ICDs) of different brands, models, and configurations were tested to determine the immunity thresholds for high-voltage electric fields (EFs) and magnetic fields (MFs) at 50/60 Hz. The EFs and MFs at the levels in workplaces are reproduced by setups using Helmholtz coils and aluminum plates, respectively, to ensure that the EM/MF exposures are controllable and reproducible. The EMI thresholds were recorded by observing the occurrences of PM or ICD dysfunctions. In addition, numerical studies on anatomical models were carried out using CST® software. The results indicate that the recorded thresholds all exceed the EF and MF public exposure limits given in the ICNIRP 2010 guidelines. No dysfunction was observed among four ICDs tested under MF exposure up to 2750 µT at 50 Hz and 2480 µT at 60 Hz. However, among the 43 PMs and 11 ICDs tested under EF exposures, potential hazards may occur below the occupational exposure level proposed in the ICNIRP guidelines.

Phantom Model Testing of Active Implantable Cardiac Devices at 50/60 Hz Electric Field.

Exposure to external extremely low-frequency (ELF) electric and magnetic fields induces the development of electric fields inside the human body, with their nature depending on multiple factors including the human body characteristics and frequency, amplitude, and wave shape of the field. The objective of this study was to determine whether active implanted cardiac devices may be perturbed by a 50 or 60 Hz electric field and at which level. A numerical method was used to design the experimental setup. Several configurations including disadvantageous scenarios, 11 implantable cardioverter-defibrillators, and 43 cardiac pacemakers were tested in vitro by an experimental bench test up to 100 kV/m at 50 Hz and 83 kV/m at 60 Hz. No failure was observed for ICNIRP public exposure levels for most configurations (in more than 99% of the clinical cases), except for six pacemakers tested in unipolar mode with maximum sensitivity and atrial sensing. The implants configured with a nominal sensitivity in the bipolar mode were found to be resistant to electric fields exceeding the low action levels, even for the highest action levels, as defined by the Directive 2013/35/EU. Bioelectromagnetics. 2020;41:136-147. © 2020 Bioelectromagnetics Society.