ECG Artifact in a Tremulous Patient
A 72-year-old woman with a history of Parkinson's disease is scheduled for a routine ECG. She has noticeable hand tremor and is unable to remain completely still. The ECG tracing shows a wandering baseline and irregular, high-frequency spikes that obscure the QRS complexes in leads I, II, and III. The technician needs to obtain a diagnostic-quality ECG to evaluate for possible atrial fibrillation.
1. What technical steps can the technician take to minimize artifact and improve ECG quality?
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The technician should first ensure proper skin preparation: clean the electrode sites with alcohol and abrade the skin to reduce impedance. Use fresh, high-quality electrodes and secure them firmly. Have the patient sit comfortably with arms supported on armrests to reduce muscle tension. Ask the patient to relax and breathe normally; if possible, perform the ECG with the patient lying down. For tremor, try to stabilize the patient's arms with pillows or ask them to clasp their hands. Set the filter settings appropriately (e.g., 40 Hz muscle artifact filter) but avoid over-filtering that could distort the QRS. Repeat the ECG if necessary, and document the presence of tremor.
2. How can the technician differentiate artifact from true atrial fibrillation in this tracing?
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Artifact from tremor typically appears as high-frequency, irregular spikes that may mimic fibrillatory waves but are often superimposed on all leads and do not disrupt the underlying QRS regularity. In atrial fibrillation, the QRS complexes are irregularly irregular, and there are no consistent P waves; instead, fine or coarse fibrillatory waves are seen. The technician should look for a lead with the least artifact (e.g., lead V1 or a limb lead with better contact) and examine the R-R intervals. If the R-R intervals are regular, artifact is more likely. Also, artifact often disappears when the patient relaxes or stops trembling. If uncertainty remains, a repeat ECG with better technique or a rhythm strip may be needed.