Electrocardiographic "pacemaker pseudo-spikes" and radio frequency interference

To present a case of apparent interference of an ECG monitor by radiofrequency interference (RFI) and to provide a brief review of RFI issues to critical care medicine.

A 74-yr-old woman, with an implanted pacemaker, underwent major spinal surgery. In the post-anaesthesia care unit, the cardiac monitor demonstrated graphic evidence of pacemaker malfunction but there was no apparent effect on the patient. Investigation by the hospital's biomedical personnel led to the conclusion that RFI was being interpreted by the monitor as abnormal pacemaker activity.

With the emergence of portable, battery-operated communication devices, there is an increased risk of RFI within hospitals. Antennas and repeaters are required to receive and boost the signal levels of these devices to improve signal quality. They are located throughout hospitals and may be situated near patient care areas. Patient monitors may receive these signals, misinterpret them as being patient-generated and output erroneous information. In the case described, the monitor was presented with RFI signals and interpreted as pacemaker spikes, generating a tracing suggestive of pacemaker malfunction. Troubleshooting strategies and minimizing the potential impacts of RFI on patient monitors are discussed.