Electromagnetic fields and their potential impact on implantable cardiovascular devices

Technology is advancing quickly. The use of electrical devices has been an integral part of our lives for a long time , yet the changing face of technology means we're being exposed to an ever increasing amount of electromagnetic interference (EMI) – the disturbance in performance levels created when an external source affects an electrical circuit.

For the majority of people, EMI doesn't affect their lives. However, some patients have an implantable cardiovascular device, which prevents arrhythmia disturbances, heart blocks or ventricular tachycardia. with these patients, EMI could cause severe problems and could prevent a patient's implantable cardioverter defibrillator (ICD) or pacemaker from functioning properly. 

With the continued increase in interactions between electromagnetic emitters and implants, there is a clear need to consistently evaluate and analyse such interactions in order to maintain the safety of such devices.

The responsibility of ensuring that patients are able to manage their risk of exposure to EMI sits on the shoulders of device manufacturers and medical staff.

What causes the increased EMI exposure? 

Technology, increased digital social interactions, telecoms and broadcasting are just some of the culprits of the exponential increase in EMI. Within the work environment, businesses can also risk exposing their employees to electromagnetic field levels through their equipment.

Emitter equipment can interfere with implantable cardiovascular devices in a number of ways, depending on the following factors:

• frequency content of the emitter;
• modulation format;
• power of the signal;
• proximity to the patient;
• coupling factors; and
• duration of exposure.

With the Control of Electromagnetic Fields at Work Regulations that came into effect in 2016[1], employers must ensure that exposure of EMI to employees is not above a certain limit value. They are also instructed to make sure that they have valid risk assessments in place, along with action plans that can consider all forms of exposure.

Although employers can take precautions, changes in technology are a disadvantage that may leave workplaces a step behind. It is expected that patients with cardiovascular devices will come up against more exposure across a broad range of frequencies.

How can EMI risks be managed?

Manufacturers will need to manage and evaluate their products to keep up with the complex electromagnetic environment and its frequencies and modulation. Patients should expect nothing less than devices that are EMI-safe by design, not by chance. Pacemaker/ICD manufacturers are incorporating state-of-the-art technology to make implantable devices less susceptible to EMI.

Doctors are being tasked with managing their patients with cardiovascular devices to make sure that exposure doesn't affect the device and cause serious injury or potentially death. The pacemaker industry is working with regulatory bodies and emitter manufacturers to educate patients and medical professionals and develop appropriate warnings when required.

Both patients and manufacturers should be aware that limitations exist and that there is not complete immunity to EMI.

Where can the medical devices manufacturing community get support?

Revised standard BS 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 to help guide the industry on this matter.

The standard specifies test methodologies that allow manufacturers to accurately evaluate the performance of their devices, and evaluate the electromagnetic compatibility of implantable cardiovascular devices.

It looks at devices that are affected by EMI transmitters operating between the following frequencies (ƒ):

• 0 Hz ≤ ƒ < 385 MHz;
• 385 MHz ≤ ƒ ≤ 3,000 MHz; and
• ƒ ≥ 3,000 MHz.

The standard sets out which emitters are most associated with each frequency and details out how to accurately test devices.

BS ISO 14117:2019also addresses the specific requirements of how to protect a device from electromagnetic fields and having the right documentation to provide to manufacturers of electromagnetic emitters to clarify their level of indemnity.

For more information, you can read about and purchase BS ISO 14117:2019from the online BSI shop.