ECG Lead Positioning

Importance of ECG

• ECG (Electrocardiogram) is a crucial diagnostic tool in medicine.
• Electrodes attached to the chest and/or limbs record voltage changes, transposed into visual tracings.

Basic Landmarks

• External chest landmarks are crucial for accurate ECG lead placement.

3-Electrode System

• Uses 3 electrodes: Right Arm (RA), Left Arm (LA), Left Leg (LL).
• Displays bipolar leads: I, II, III.
• Optimal placement on chest wall, equidistant from the heart.

5-Electrode System

• Uses 5 electrodes: RA, RL, LA, LL, and Chest.
• Displays bipolar leads: I, II, III and a single unipolar lead.
• The unipolar lead varies with the chest lead position (V1-6).

12-Lead ECG

• 10 electrodes needed to produce a 12-lead ECG.
• 4 electrodes on limbs (RA, RL, LA, LL) and 6 on precordium (V1-6).
• Monitors 12 leads: V1-6, I, II, III, aVR, aVL, aVF.
• Interprets specific heart areas:
  • Inferior: II, III, aVF
  • Lateral: I, aVL, V5, V6
  • Anterior: V1-4

Precordial Lead Placement

• V1: 4th intercostal space (ICS), right of sternum.
• V2: 4th ICS, left of sternum.
• V4: 5th ICS, mid-clavicular line.
• V3: Between V2 and V4.
• V5: 5th ICS, anterior axillary line.
• V6: 5th ICS, mid-axillary line.

Additional Lead Placements

Right-Sided ECG

• Place leads V1-6 in a mirror-image on the right chest.
• Optionally, move V3-6 to the right chest, keeping V1, V2.

V4R Lead

• Placed in the 5th right ICS, mid-clavicular line.
• Important for diagnosing right ventricular (RV) myocardial infarction (MI).

Posterior Leads

• V7: Left posterior axillary line.
• V8: Tip of left scapula.
• V9: Left paraspinal region.

Lewis Leads (S5-Lead)

• Detects atrial activity, useful in atrial flutter and wide complex tachyarrhythmia.
• Placement: RA on manubrium, LA on 5th ICS right sternal border, LL on right lower costal margin.

Fontaine Leads

• Used for epsilon wave detection, named after Guy Hugues Fontaine.
• Placement: RA over manubrium, LA over xiphoid process, LL in V4 position (5th ICS MCL).
• Three bipolar chest leads: FI, FII, FIII for right ventricle potentials.

ECG Electrode Guide

• Visual representations and educational videos available for ECG lead placements.

Related and Advanced Reading

• Additional resources and courses on ECG mastery and interpretation are available for further learning.
• Textbooks and online materials offer comprehensive ECG education.

Notable Contributors

• Contributions by Mike Cadogan, emergency physician and educator.

Further Resources

• ECG Library Basics, Clinical Cases, and Quiz available for practice and deeper understanding.