Pacemaker sensitivity to 50 Hz noise voltages.

Area of Science:

• Biomedical Engineering
• Electrophysiology
• Medical Device Technology

Background:

• European standards mandate pacemakers (PM) to resist electromagnetic interference (EMI).
• Pacemaker sensitivity settings (SS) influence susceptibility to 50 Hz noise, a common EMI parameter.
• Understanding SS and noise thresholds is vital for protecting PM patients from EMI.

Purpose of the Study:

• To determine the borderline sensitivity setting (SS) for 50 Hz noise in pacemakers.
• To evaluate the signal-to-noise ratios (S/N) of various pacemaker models against 50 Hz noise.
• To provide recommendations for programming SS to ensure patient safety from EMI.

Main Methods:

• Explantation and measurement of 189 pacemakers implanted in 1998 or later.
• Measurement of ventricular SS and 50 Hz noise thresholds according to European standards.
• Derivation of signal-to-noise ratios (S/N) from heart test and noise test signals.

Main Results:

• All tested pacemakers exhibited S/N ratios below 1 for 50 Hz noise, indicating less amplification of heart signals than noise.
• Medtronic pacemakers showed extreme sensitivity to continuous 50 Hz noise at low heart test amplitudes.
• Noise immunity increased with higher heart test signal amplitudes.

Conclusions:

• Pacemakers reacted to 50 Hz noise as if it were heart signals, leading to inhibition or asynchronous pacing.
• A sensitivity setting (SS) of 2 mV does not guarantee noise tolerance up to 2 mV as required by European standards.
• Programming SS to approximately 3 mV in Medtronic pacemakers is recommended for optimal protection against pulsed and continuous 50 Hz noise.