Digital cellular telephone interaction with implantable cardioverter-defibrillators

Area of Science:

• Biomedical Engineering
• Cardiology
• Electromagnetics

Background:

• Implantable cardioverter-defibrillators (ICDs) are crucial for managing life-threatening arrhythmias.
• Mobile cellular telephones generate electromagnetic interference (EMI) that could potentially affect electronic medical devices.
• Understanding potential interactions between cellular phones and ICDs is vital for patient safety.

Purpose of the Study:

• To assess in vivo and in vitro whether EMI from North American Digital Communications (NADC)/Time Division Multiple Access-50-Hz (TDMA-50) mobile cellular telephones interferes with ICD operation.
• To verify these findings using a selection of telephones representing worldwide systems.

Main Methods:

• In vivo testing involved 41 patients with Medtronic ICDs exposed to an AT&T 6650 digital telephone (NADC/TDMA-50).
• In vitro testing included antenna-generated far-field exposure and near-field exposure using analog and digital cellular telephones.
• Testing evaluated ICD response to EMI under various simulated conditions.

Main Results:

• No oversensing or interference with ICD operation was observed in any of the 41 patients during the in vivo study.
• In vitro far-field testing showed no ICD sensing interference from TDMA-50 and Global System Mobile (GSM) telephone modulation frequencies.
• Near-field tests indicated no interaction with normal ICD operation, except for static magnetic fields activating the reed switch at close proximity (< or = 0.5 cm).

Conclusions:

• TDMA-50 cellular telephones did not demonstrate interference with the tested ICD models.
• A recommendation is made to maintain a distance of at least 15 cm (6 inches) between digital cellular telephones and ICDs.
• While EMI is not an issue, the static magnetic field's effect on the reed switch warrants caution regarding device placement.