Which of the following is identified as a common cause of EKG artifact in EEG/EOG channels due to electrode placement?

Which of the following is identified as a common cause of EKG artifact in EEG/EOG channels due to electrode placement?

• A. M1 and M2 placed directly on the auricular branch of the posterior auricular artery
• B. Improper EKG patch placement
• C. Incorrect filtering
• D. Ambient noise

Answer: (A)

The main idea is that electrode placement can pick up physiological signals from nearby structures, not just brain activity. When M1 and M2 are placed directly on the auricular branch of the posterior auricular artery, the pulsatile arterial flow is very close to the electrode tips. That pulsation couples into the electrode and appears in the EEG and EOG channels as a distinct EKG-like waveform, creating an artifact that looks like cardiac activity. This is a well-known source of EKG artifact tied specifically to where those mastoid/behind-the-ear electrodes sit. To minimize it, place the electrodes behind the ears or on the mastoid bone away from major arterial branches. The other options describe issues that either affect different leads (improper EKG patch placement), general signal processing (incorrect filtering), or environmental noise, none of which explain an EKG-type artifact arising from electrode position near the artery.

The main idea is that electrode placement can pick up physiological signals from nearby structures, not just brain activity. When M1 and M2 are placed directly on the auricular branch of the posterior auricular artery, the pulsatile arterial flow is very close to the electrode tips. That pulsation couples into the electrode and appears in the EEG and EOG channels as a distinct EKG-like waveform, creating an artifact that looks like cardiac activity. This is a well-known source of EKG artifact tied specifically to where those mastoid/behind-the-ear electrodes sit. To minimize it, place the electrodes behind the ears or on the mastoid bone away from major arterial branches. The other options describe issues that either affect different leads (improper EKG patch placement), general signal processing (incorrect filtering), or environmental noise, none of which explain an EKG-type artifact arising from electrode position near the artery.