Cardiac artifacts in EEG recordings can be categorized into different types based on their sources and characteristics.
1. Electrical
Cardiac Artifacts:
o Description: Result from
electrical effects of cardiac activity.
o Characteristics:
§Time-Locked: Occur in
relation to cardiac contractions, synchronized with ECG complexes.
§Appearance: May resemble
ECG signals but with differences due to distance from the heart and suboptimal
axis for visualization.
o Types:
§Pacemaker
Artifact:
Characterized by high-frequency polyphasic potentials with a shorter duration
than ECG artifacts, often showing a broader field of distribution.
§ECG Artifact: Represents the
actual ECG signal recorded from head electrodes, but may not always resemble a
typical ECG due to recording distance and axis issues.
2. Mechanical
Cardiac Artifacts:
oDescription: Arise from
mechanical effects of cardiac activity.
o Characteristics:
§ Source: Associated with
circulatory pulse and movements of the head or body during cardiac
contractions.
§ Waveform: May exhibit
periodic slow waves, saw-tooth patterns, or sharply contoured waveforms.
o Types:
§ Pulse Artifact: Manifests as a
slow wave following the ECG peak, commonly observed over frontal and temporal
regions, and may be altered by pressure on the electrode.
§ Ballistocardiographic
Artifact:
Results from slight head or body movements during cardiac contractions, with a
waveform similar to pulse artifact but more widespread.
Understanding the
characteristics and distinctions between electrical and mechanical cardiac
artifacts in EEG recordings is essential for accurate interpretation and
differentiation from genuine brain activity. Proper identification of these
artifacts can help improve the quality and reliability of EEG data for clinical
analysis and diagnosis.
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