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Reducing ECG artifact

Artifact when taking a 12 lead ECG is a very common occurrence, especially in a busy GP practice. Poor signal quality can cause noise, or artifact, on the ECG machine, which in turn can lead to inaccurate analysis of the final test.

Thousands of 12 lead ECGs are performed every day in primary care and ensuring the highest quality ECG tests are performed will reduce patients having to be recalled for the test to be performed again or being referred to hospital for further testing. 

The following are a range of tips and best practices on reducing ECG artifact when taking an ECG in your practice:

  1. Perform good skin preparation - The build-up of oils and residue on the skin increases the resistance to the conduction of the electrical signal when taking an ECG. Therefore, it is vital to prepare the patient’s skin properly. Good skin preparation should include: 
        • Shaving or clipping the patient’s chest hair if present.
        • Rubbing the skin vigorously with a gauze pad.
        • Rubbing the skin with either isopropyl alcohol or soap and water to remove skin oils.
  1. Ensure the patient is comfortable and relaxed during the test – Making sure the patient is comfortable and relaxed will reduce muscle tremors and movement as much as possible. Both of these can impair the quality of ECG recordings.
  1. Use high-quality ECG electrodes - Ensure you are using a high-quality ECG electrode, such as the AMBU SUPAtab which features a highly conductive wet gel that has been specially formulated to provide the best adhesion possible. Also, check that the electrodes you are using are in date and that the electrode gel is fresh and moist. The electrode gel greatly affects the transmission of signals from the skin to the electrode.
  1. Ensure correct lead wire positioning - Check that the chest and limb leads are placed in the correct position and that the electrodes have good contact with the skin. Download our free ECG Lead Placement guide as a reference for correct lead wire position. Also, ensure that lead wires are not placed over bones, irritated skin or areas where there are lots of muscle movement.
  1. Clean your crocodile clips - Crocodile clip connections should be cleaned prior to every test. This helps to prevent the build up of gel on the clips which occurs over time and can affect conductivity.
  1. Check the patient cable and lead wires – Ensure that the patient cable is correctly connected to the ECG system and that no gaps exist between the connectors. You should periodically check patient cables and lead wires for breaks and cracks and replace as required.
  1. Check for AC interference - 50/60 Hz. interference looks like small regular peaks and produces a wide, fuzzy baseline on the ECG trace. There are several possible causes of AC interference that you should check, including:
        • Electrical wires in the walls, ceiling or floor.
        • The presence of other electrical equipment in the room
        • Improper grounding of the ECG device.

References

1. Knight BP, Pelosi F, Michaud GF, Strickberger SA, Morady F. Clinical consequences of electrocardiographic artifact mimicking ventricular tachycardia. N Engl J Med 1999;341:1270–1274.

2. Hurst JW. Images in cardiovascular medicine: “switched” precordial leads. Circulation 2000;101:2870–2871.

3. Michael Smith M.S., B.S.E.E. Rx FOR ECG MONITORING ARTIFACT. Critical Care Nurse 1984

4. The Society for Cardiological Science and Technology, Clinical Guidelines by Consensus, Number 1, Recording a standard 12-lead electrocardiogram, April 2005, Review Date: April 2006