Pacemaker warning on bioimpedance sensing in wearables

Pacemaker warning on bioimpedance sensing in wearables

Technology News |
By Nick Flaherty

Researchers are warning that wearables using bioimpedance could interfere with the operation of pacemakers.

This is over and above the issues of EMI interference from smartwatches that is well publicised.

The Samsung Galaxy Watch 4, Fitbit Aria 2 smart scales and a smart ring use a small current to determine the person’s body composition such as skeletal muscle mass or fat mass, level of stress, or vital signs, such as breathing rate.

However none of these are approved by regulators in the US for use with pacemakers and this is already made clear by manufacturers.

Researchers at the University of Utah simulated the interference at pacing electrodes on both male and a female computable models. A benchtop evaluation of representative implantable devices from three different manufacturers as specified in the ISO 14117 standard also was performed.

The study showed that the electrical currents from the bioimpedance sensor  could trick the heart into thinking it is beating fast enough, preventing the pacemaker from doing its job when it is supposed to. This might also trigger false pulses from an implanted defibrillator.

“This study raises a red flag,” said lead investigator Dr Benjamin Sanchez Terrones at the Department of Electrical and Computer Engineering, University of Utah. “We have done this work in simulations and benchtop testing following Food and Drug Administration accepted guidelines, and these gadgets interfere with the correct functioning of the CIEDs we tested. These results call for future clinical studies evaluating the translation of our findings to patients wearing implantable devices and using these wearable devices.”

“Our research is the first to study devices that employ bioimpedance-sensing technology as well as discover potential interference problems with implantable devices such as pacemakers. We need to test across a broader cohort of devices and in patients with these devices. Collaborative investigation between researchers and industry would be helpful for keeping patients safe,” he said.

“The scientific community doesn’t know about this,” he said. “No one has looked at whether this is a real concern or not.”

The simulations showed evidence of interference with voltage values exceeding threshold values defined in the ISO 14117 standard and the level of interference varied with the frequency and amplitude of the bioimpedance signal, and between male and female models.

 The level of interference generated with smart scale and smart rings simulations was lower than with smart watches. The voltage generators were also susceptible to oversensing and inhibiting pacemaker operation different signal amplitudes and frequencies.

The study was published in Heart Rhythm, the official journal of the Heart Rhythm Society, the Cardiac Electrophysiology Society, and the Pediatric & Congenital Electrophysiology Society:

 “If the pacemaker gets confused by interference, it could stop working during the duration that it is confused. If that interference is for a prolonged time, the patient could pass out or worse,” said co-author Benjamin Steinberg, associate professor of medicine at the university.

For other types of medical devices such as implantable cardioverter-defibrillators, which not only act as a pacemaker but can also shock the heart to restore a regular heart rhythm, a wearable device with bioimpedance could trick the defibrillator into delivering the patient an unneeded electric shock, which can be painful.


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