Underrecognized Interaction Between PICO Dressings and Pacemakers: A Case From the ICU

Modern pacemakers incorporate a magnet-responsive switch that, on exposure to a sufficient static magnetic field, converts the device to fixed-rate asynchronous (magnet-mode) pacing. This is designed behaviour rather than malfunction. Interactions between this feature and magnet-containing medical equipment are underrecognised. The PICO 7 negative pressure wound therapy (NPWT) system contains a magnet in its pump unit, which the manufacturer states can interfere with nearby pacemakers.

An 81-year-old man was admitted to the High Dependency Unit after right hemicolectomy. He had atrial fibrillation with a slow ventricular response and a permanent pacemaker programmed VVI at 60 beats per minute. Overnight, telemetry showed a sustained paced rate of 100 beats per minute; he was asymptomatic. The PICO 7 pump unit was found resting on his chest, over the pacemaker generator. Repositioning the pump to the foot of the bed returned the paced rate to 60 beats per minute immediately, and device interrogation the following day confirmed normal pacemaker function.

The fixed rate of 100 beats per minute, its dependence on pump position and immediate resolution on removal are characteristic of magnet-mode activation rather than generic electromagnetic interference. Although the patient was asymptomatic, a sustained rate of 100 beats per minute carried a risk of myocardial ischaemia and heart failure decompensation given his cardiac history. Recognition and a simple bedside intervention resolved the episode.

Magnet-containing medical equipment placed near a cardiac implantable electronic device can trigger magnet-mode pacing. The risk depends on the position of the magnet-bearing component, not on the wound site. An unexplained change in a paced rate should prompt early consideration of a nearby magnetic source, because the remedy may be immediate and at the bedside.