‘Smart’ Devices With Bioimpedance Tech May Interfere With Cardiac Implants

It’s possible that consumer “smart” devices that come with bioimpedance technology to provide measurements of body composition can interfere with certain cardiac implantable electronic devices (CIEDs), according to an experimental study.

The technology, which works by applying an imperceptible electrical current and then evaluating the body’s response, has been integrated into health-monitoring products like scales, watches, and rings to reflect various fat, muscle, and body water parameters.

These products often have disclaimers advising patients with implanted electronic medical devices to not use them, and the current study suggests that, indeed, there is at least the potential for interference that could cause CIEDs to function improperly.

Using both simulations and benchtop testing, Gia-Bao Ha, BSc (University of Utah, Salt Lake City), and colleagues showed that the level of interference was influenced by the frequency and amplitude of the bioimpedance signal, as well as other factors. Experiments with cardiac resynchronization therapy-defibrillator (CRT-D) devices from three different manufacturers demonstrated the potential for oversensing and pacing inhibition, which could have serious consequences.

“The present findings do not recommend the use of these devices in this population due to potential interference,” the researchers write in a study published online last week in Heart Rhythm.

Senior author Benjamin Sanchez, PhD (University of Utah), clarified that it remains unknown whether the results obtained here have clinical implications for patients with CIEDs. “To answer that question, we need more studies. This is just the tip of the iceberg. It’s just pointing the research community to look at something that may have gone unnoticed, and part of the reason may be because consumer technology is moving at a much faster pace” than what the scientific community can keep up with, Sanchez told TCTMD. “We don’t think there is a reason to be concerned at all at this point. It’s just that we need more data and more studies to get a better sense.”

For now, Sanchez said, “as a precautionary measure, we feel that until more data is available and more clinical studies have been performed, to be on the safe side, it would be better not to use it.”

We don’t think there is a reason to be concerned at all at this point. It’s just that we need more data and more studies to get a better sense. Benjamin Sanchez

Among other uses, bioimpedance technology has been shown to have clinical value in the cardiology realm, by detecting edema in the lungs and limbs as an indicator of worsening heart failure, the researchers note. Nonetheless, the US Food and Drug Administration has not cleared any consumer bioimpedance devices for use in patients with CIEDs because of the potential for electrical interference.

To explore that question, the investigators used simulations with computable human models and benchtop testing to compare results of various electrical signals with maximum values defined in the ISO 14117 electromagnetic interference standard. These represent the voltage threshold cutoffs that CIED manufacturers are required to use to establish safety in the types of electromagnetic environments patients will run into.

First, simulations showed interference at pacing electrodes attached to an implantable cardioverter-defibrillator (ICD) and permanent pacemaker with voltage values exceeding the standard threshold values. The level of interference was lower with smart scales and rings than with smartwatches and varied according to a multiple factors, including the frequency and amplitude of the signal, where on the body the signal was applied, pacing mode, and the distance between the anode and cathode.

Next, benchtop testing of three CRT-D devices from major manufacturers, which were in basic pacing modes with standard programming, “demonstrated susceptibility to oversensing and pacing inhibition at different signal amplitudes and frequencies,” the researchers report.

Moving forward, Sanchez said, these types of simulation and benchtop studies will have to be considered in the context of clinical studies in order to get a more-holistic view of the potential interference problem. He noted that because of differences between smart devices, CIEDs, and patient populations, the results of any given study can be applied only to the specific devices and types of participants included.

“Given our findings,” he and his colleagues write, “it is imperative to extend this study to test [a] broader variety of hardware and settings and then test patients with CIEDs to determine the translation of our findings to patients using such consumer electronics.”