Estimation of the voltage induced at the input of a pacemaker
This tool allows to calculate the voltage induced at the input terminals of a pacemaker, according to its exposure conditions (in particular, the values of electric field intensity and/or magnetic field), through the implementation of the formulas reported in the appendix of the standard CEI EN 50527-2-1 ed. 2 (2016), with reference to the worst-case situation, where the area formed by the pacemaker and the electrocatheter in the human body is 225 cm2.
The induced voltage value thus obtained can be compared with the immunity levels that pacemakers must satisfy, at various frequencies, to verify their compatibility under actual exposure conditions.
The instrument can be used for frequencies between 16.6 Hz and 60 Hz, and between 150 kHz and 450 MHz. In the range between 60 Hz and 150 kHz there are no validated studies that allow the electric field to be correlated with the induced voltage on the pacemaker, therefore the instrument does not support this frequency range.
In the range from 16.6 Hz to 60 Hz, two formulas have been implemented to distinguish the case of sensing of the pacemaker programmed in unipolar or bipolar. These take into account the assumption made in the technical standard EN 45502-2-1:2003, according to which the maximum induced voltage in unipolar mode is always at least 10 times greater than in the bipolar case. For frequencies above 150 kHz, only the unipolar case is considered, regardless of the pacemaker programming mode.
The calculation is performed by entering the frequency of interest (Hz) and the maximum peak values of the electric field (V/m) and magnetic field (A/m) measured.
The induced voltage value obtained is compared with the immunity levels that pacemakers must satisfy, at the various frequencies, in the conducted immunity tests provided for in the technical standard EN 45502-2-1:2003 and reported in the table.
Immunity limits of pacemakers (red line in the graph) for conducted disturbances in the frequency range [16 Hz; 450 MHz] according to the tests indicated in Standard 45502-2-1: Active implantable medical devices. Particular requirements for active implantable medical devices intended to treat bradyarrhythmia (cardiac pacemakers).
| Frequency range | Test signal amplitude (peak-to-peak) | Paragraph Standard 45502-2-1 |
|---|---|---|
| [16.6 Hz; 1 kHz] | 27.5.1 | |
| [1 kHz; 3 kHz] | ||
| [3 kHz; 167 kHz] | ||
| [167 kHz; 1 MHz] | 27.5.2 | |
| [1 MHz; 10 MHz] | ||
| [10 MHz; 450 MHz] | 27.5.3 |
In the case of bipolar measurements, the test signal amplitudes are reduced by a factor of 10.
Estimation of the induced voltage (green symbol in the graph) across a pacemaker as a function of the electric and magnetic field – worst case conditions on a loop of area = 225 cm2.
: maximum induced voltage in open circuit, expressed as a peak-to-peak value (V)
: instantaneous value of the measured electric field (V/m)
: instantaneous value of the measured magnetic field (A/m)
| Frequency range |
|
Paragraph Standard 50527-2-1 | |
|---|---|---|---|
| [16.6 Hz; 60 Hz] | Unipolar | E.3.5.1 | |
| Bipolar | |||
|
[60 Hz; 150 kHz]
|
Unipolar | E.3.3 | |
| Bipolar | |||
| [150 kHz; 5 MHz] | E.3.6 | ||
| [5 MHz; 30 MHz] | E.3.7 | ||
| [30 MHz; 200 MHz] | E.3.8 | ||
| [200 MHz; 400 MHz] | |||
| [400 MHz; 450 MHz] | |||
Keywords: Induced voltage, Pacemaker