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ECG Basics

Recording the ECG

February 15th, 2021


Correct technique in recording ECGs is imperative for the diagnosis of electrical disorders of the heart. Incorrect technique may result in artefact, an unusable result or even misinterpretation of the ECG.
  • How to Perform

  • 1
    Prepare the skin - ensure that it is dry; shave excessive chest hair; gently abrade the skin if required
  • 2
    Place the electrodes as below
  • 3
    Ask the patient to remain still, not speak and breath slowly (if possible)
  • 4
    Record the ECG - at speed 25mm/sec and gain 10mm/mV
  • 5
    Look for electrical interference and baseline wander, and assess need to rerecord ECG
  • 6
    Consider a rhythm trace if arrhythmia is evident

Limb Electrode Placement

  • Positions

  • LA - Left wrist / forarm
  • RA - Right wrist / forearm
  • LL - left ankle / leg
  • RL - right ankle / leg
Placement of arm leads on the shoulders and leg leads on the pelvis can lead to significant changes in amplitude and waveform that can affect interpretation, and therefore the ECG should be marked if this alternative placement is used. An ECG measured using torso lead placement should not be compared to an ECG measured using standard limb placement.

Chest Electrode Placement

  • Chest Electrode Placement
  • Positions

  • V1 - 4th intercostal space at the right sternal edge
  • V2 - 4th intercostal space at the left sternal edge
  • V3 - between V2 and V4
  • V4 - fifth intercostal space in the mid-clavicular line
  • V5 - fifth intercostal space between V4 and V6
  • V6 - fifth intercostal space in the mid-axillary line
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