Artifact 101 Part II: Understanding and Fixing Muscle Tremor and Movement Artifacts in ECG Recordings

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Following our discussion on powerline interference, let’s explore two other common ECG disruptors: muscle tremor artifacts and movement artifacts. Learn to identify, differentiate, and resolve these issues for cleaner recordings.

Know Your Artifacts: A Quick Comparison

Feature Powerline Interference Muscle Tremor Movement Artifact
Pattern Regular fine spikes (50/60Hz) Irregular fine “shivering” Large, irregular waves
Cause Electrical interference Muscle contractions Patient movement
Best Fix Improve skin contact Relax muscles Stabilize patient

 

Muscle Tremor Artifact: The Subtle Saboteur

Figure 1 – Muscle tremor artifact example

  • Identification:
    • Irregular, fine baseline oscillations (See Figure 1)
    • Common causes: shivering, purring (cats), standing position
  • Practical Solutions:
    • Optimal Positioning:
      • Move clips away from large muscle groups (use paws/wrists/elbows instead of thighs) (See Figure 2)
      • Right lateral recumbency / Sitting position often better than standing
      • Gentle limb support reduces tremors

Figure 2 – Move clips away from large muscle groups (use elbows/wrists/paws instead of thighs)

    • General Techniques:
      • Ensure limbs are relaxed and supported
      • Warm cold/stressed patients
      • Wait 5 minutes after restraint for tremors to subside

 

Movement Artifact: The Obvious Offender

Figure 3 – Movement artifact example

  • Identification:
    • Large, irregular baseline swings (See Figure 3)
    • Often synchronizes with breathing or struggling
  • Proven Correction Methods:
    • Patient Stabilization:
      • Use towel wraps for cats (“burrito method”)
      • Have assistant gently support limbs
    • Equipment Management:
      • Secure loose cables to prevent tugging
      • Ensure clips are firmly attached
    • Recording Timing:
      • Capture between breaths for panting dogs
      • Take multiple recordings if needed

 

 

Troubleshooting Flow

  1. Identify artifact type using the comparison table
  2. Apply species-specific methods
  3. Verify with re-recording

 

 

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