An international standard, ISO 14117:2019, outlines electromagnetic compatibility (EMC) test protocols for various active implantable medical devices.
The heart typically pumps at 60-100 beats per minute, but sometimes it doesn’t. Sometimes, people have irregularities when it comes to the vital organ pounding in their chest—bradycardia, tachycardia, etc. Thankfully, we live in a time when the marvelous blend of modern science and advanced engineering permits comfortable, healthy lives.
This is due to active implantable medical devices, including implantable cardiac pacemakers, implantable cardioverter defibrillators (ICDs), and cardiac resynchronization devices.
However, the same world that has advanced these medical devices has also seen the proliferation of electronic devices. Even in the hospital, patients are exposed to numerous electromagnetic (EM) emitters during the day-to-day activities. This can seem perilous, especially considering the potential life-sustaining nature of these devices.
The potential for emitter equipment to interfere with active pacemakers and other implantable cardiovascular devices is dependent on several factors. According to the Introduction of ISO 14117:2019, the EM compatibility of pacemakers and ICDs depends on the frequency content of the emitter, modulation format, power of the signal, proximity to the patient, coupling factors, and duration of exposure.
In lower frequency bands (0 Hz ≤ ƒ < 385 MHz), there are numerous EM emitters, including both new technologies and more-conventional ones, such as broadcast radio and television. At higher frequencies (385 MHz ≤ ƒ < 3,000 MHz), you have personal hand-held communication devices, such as wireless telephones and two-way radios. These frequencies have become increasingly common in the Twenty-First Century, and therefore, so has their interaction with patients with implantable cardiovascular devices.
ISO 14117:2019 – Active Implantable Medical Devices – Electromagnetic Compatibility – EMC Test Protocols For Implantable Cardiac Pacemakers, Implantable Cardioverter Defibrillators And Cardiac Resynchronization Devices offers specifications for these two frequency ranges. The document specifies test methodologies to evaluate the EMC of and offers performance limits for active implantable cardiovascular devices. The standard does not cover testing above 3,000 MHz.
ISO 14117:2019 also provides manufacturers of EM emitters with information about the expected level of immunity of these devices.
Changes to ISO 14117:2019
The first edition of this standard in 2012 was designed for pulse generators used with endocardial leads or epicardial leads. However, as mentioned in a “NOTE” found in the scope of ISO 14117:2019:
“At the time of this edition, the authors recognized the emergence of technologies that do not use endocardial leads or epicardial leads for which adaptations of this part will be required. Such adaptations are left to the discretion of manufacturers incorporating these technologies.”
In addition to language clarifications, ISO 14117:2019 contains the following changes:
- New definitions added for “interference mode” and “transient exposure.”
- The breakpoint between injected voltage testing and radiated testing reduced from 450 MHz to 385 MHz. This change is meant to account for new wireless services.
- Section 4.4, “Protection from malfunction caused by temporary exposure to CW sources,” modified.
- New section 4.10, “Transient exposure to stationary low-frequency electromagnetic field sources in the frequency range 16.6 Hz to 167 kHz.”
- Multiple electrode leads, such as those with IS-4 and DF-4 connectors, are now recognized by the ISO 14117:2019 standard.
- New section 7.4, “Minimum separation distance from hand-held transmitters.”
- The table of emitters and frequencies was eliminated from Annex B, “Rationale for test frequency ranges.”
- New informative Annex N, “Connections to DUTs having ports with more than two electrode connections.”
- New informative Annex O, “Example method for evaluation of transient and permanent malfunction of a CIED due to temporary exposure to low frequency (<167 kHz) electromagnetic fields.”
This standard was prepared by Technical Committee ISO/TC 150, Implants for surgery, Subcommittee SC 6, Active Implants.
ISO 14117:2019 – Active Implantable Medical Devices – Electromagnetic Compatibility – EMC Test Protocols For Implantable Cardiac Pacemakers, Implantable Cardioverter Defibrillators And Cardiac Resynchronization Devices is available on the ANSI Webstore.