An In Vitro Study of Magnetic Field Interference with an Electronic Shunt Programmer

Programmable shunts play a valuable role in the treatment of hydrocephalus. However, the use of magnets in programming these valves has caused obstacles in today's magnetized world. Previous studies have reported problems with magnetic toys and electronics unintentionally reprogramming shunt valves. This study investigated how an Apple Watch can interfere with the Codman CERTAS Plus electronic programmer.

In this in vitro study, we tested the magnetic field emitted by Apple Watch Series 3, 4, 5, and 6 using an electromagnetic field tester at distances of 0-50 mm. We conducted 20 trials of shunt programming and shunt setting reading with and without each watch.

All 4 watches generated significant magnetic fields. Maximum magnetic fields were Series 3, 165.73 millitesla (mT); Series 4, 144.91 mT; Series 5, 131.09 mT; and Series 6, 130.68 mT. All 4 watches interfered with the programmer's ability to correctly read and program the valve setting.

The Codman CERTAS Plus electronic programmer detects the magnetic field emitted from an Apple Watch and mistakes it for the valve, rendering programming difficult. These smartwatches and similar electronic devices should be kept away from the programmer and not worn by health care providers to avoid inappropriate readings and setting changes.