Artifact 101: Understanding and Fixing Powerline Interference in ECG Recordings

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ECG artifacts—unwanted disturbances in the recording—can obscure important waveforms and lead to misinterpretation. One of the most common and frustrating artifacts is Powerline interference (50/60 Hz electrical noise. 50 Hz in Europe, Africa, most of Asia, Australia, and parts of South America. 60 Hz in North America, parts of South America, and some Asian countries e.g., Japan, South Korea, Philippines), which often appears as a thick, fuzzy baseline or regular fine spikes (see Figure 1).

 

Figure 1 – Example of (a) Powerline interference  vs. (b) clean ECG

(a)

(b)

 

Recognizing and resolving this issue quickly is key to obtaining clean, diagnostic-quality tracings.

What Causes Powerline Interference?

1. Poor skin-to-electrode contact

Powerline noise stems from alternating current (AC) in the surrounding environment, but the most common cause in veterinary practice is poor skin-to-electrode contact. Even when clips are securely attached and the patient is still, severe noise may persist due to:

  • Clips touching fur instead of skin – Hair acts as an insulator, preventing proper electrical conduction. So the strongest signal in the environment – powerline interference, is recorded, instead of the ECG signals from the body. 
  • Dry or dirty skin – Oils, debris, or excessive fur can increase impedance.
  • Insufficient conduction medium – Alcohol or water helps, but conductive gel is far more effectivef especially in thick-coated or dehydrated patients. 

 

Figure 2 – Proper clip placement on  (a) skin vs (b) fur

 

(a)

(b)

  • How to Identify and Fix Skin Contact Issues
    • Clip Placement: Part the fur and ensure direct metal-to-skin contact.
    • Improve Conductivity:
      • Alcohol or water reduces impedance temporarily.
      • Conductive gel (e.g., ECG gel or ultrasound gel) provides a stable connection.
      • Lightly abrade the skin (if necessary) in long-haired or scaly patients.

If noise persists, move to environmental troubleshooting.

 

2. Is the Environment Causing the Noise?

Figure 3 – Testing environmental noise by moving away from interference sources.

 

 

Strong AC interference can come from:

  • Faulty or ungrounded equipment (e.g., fluorescent lights, radiography machines).
  • Nearby power cables† or large electrical devices.
  • Poor clinic wiring or grounding issues.

† CardioBird is a battery-powered portable ECG – never record ECGs while the device is charging.

  • How to Test for Environmental Noise 🔍
    • Insulate the Patient: Place a thick, dry towel or rubber mat under the animal to reduce ground loops.
  • Perform a Quick Environmental Check:
    1. Place your fingers on CardioBird’s electrodes to record your own ECG.
    2. Walk away from the current location (e.g., exam table, treatment area).
    3. If the noise significantly decreases, the original spot has strong AC interference.
  • Permanent Fixes for Problematic Environments
    • Relocate ECG testing away from large machines or power sources.
    • Check clinic wiring – Faulty outlets or unshielded cables can introduce noise.

 

Key Takeaways for Clean Recordings

✅  Always ensure direct skin contact – Clip placement matters more than restraint.
✅  Use conductive gel for high-impedance patients (better than alcohol/water).
✅  Test the environment if noise persists—sometimes, moving a few feet away helps!

By following these steps, you’ll minimize artifacts and get clear, interpretable ECGs faster—keeping diagnostics efficient and accurate.

 

Next Issue: We’ll tackle muscle tremor artifact and movement artifact—how to spot them and keep wiggly patients still for a perfect reading!

Run flawless ECGs with CardioBird! 🚀