Does a weighted-peak index below unity ensure safety for bearers of cardiac implantable electronic medical devices? A weighted-peak analysis of the ISO 14117 immunity test signals

International standards governing the electromagnetic compatibility (EMC) of cardiac implantable electronic devices (CIEDs) link the immunity levels of cardiac pacemakers (PMs) and implantable cardioverter-defibrillators (ICDs) to the exposure limits recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). If the general-public reference levels (without time averaging) are not exceeded, the CIEDs are expected to work uninfluenced, and thus, the exposure can be considered to pose a low risk. However, the ICNIRP reference levels are root-mean-square (RMS) quantities defined for single-frequency sinusoidal fields. In case of non-sinusoidal and multifrequency exposures, the weighted-peak (WP) index is the reference procedure used in practical compliance assessment. Whether a WP value below unity implies exposure conditions less severe than those represented by CIED immunity test is still an open question. In this work, we reconstruct the equivalent magnetic field that would induce the ISO 14117:2019 immunity-test signals and we compute the weighted-peak index of these waveforms over the range 16.6 Hz–10 MHz, against the ICNIRP 1998 general-public reference levels. The analysis is performed both in the time domain (digital IIR weighting filter reproducing the gain of a Narda ELT-400 probe) and in the frequency domain (FFT). The weighted-peak index is found to fall below 1 in two frequency ranges: around 1 kHz and above 800 kHz. This shows that satisfying the WP threshold of 1 does not, by itself, guarantee the absence of interference risk for PM/ICD users in those frequency ranges. Given the WP obtained by our analysis, a practical and conservative approach would be to lower the threshold of WP to 0.6 when the risk analysis includes CIEDs.