ECG artifact is defined as interference not related to the heart and can be caused by which of the following?

• A. Outside electrical interference, poor electrode contact, tremors, or equipment malfunctions
• B. Active myocardial ischemia
• C. Normal sinus rhythm variation
• D. Calibration of the monitor

Answer: (A)

ECG artifact is interference that doesn’t come from the heart’s electrical activity. It shows up on the tracing as noise or distortions that obscure the true cardiac signal. This kind of artifact can stem from outside electrical interference (like mains noise from nearby devices), poor electrode contact (loose or dried skin causing high impedance), tremors or movement by the patient, or problems with the monitoring equipment (faulty leads or cables). These sources create noncardiac signals that ride on top of the heart’s rhythm, making it hard to interpret. By contrast, active myocardial ischemia would produce real, physiologic changes in the ECG such as ST segment deviations or T-wave changes, which are true cardiac events, not artifacts. Normal sinus rhythm variation is just normal cardiac rhythm changes, not noise, and calibration of the monitor is a device procedure, not a source of interference from the heart.