LECTURES:
1. Vectors & Electrodes
2. EKG Paper
3. Standard Leads
4. Right-Sided Leads
5. Posterior Leads
6. Localizing ECG Leads
7. Full ECG Course
8. The EKG Guy Lectures

Overview:

• Positive end gets lead name
• 2 lead systems: (1) hexaxial & (2) precordial

Hexaxial System (Limb/Extremity Leads)

• Coronal view
• 6 limb leads: I, II, III, aVR, aVL, aVF
• I – from R-arm to L-arm
• II – from R-arm to L-leg
• III – from L-arm to L-leg

Note: I + III = II (eg, if QRS in I is 4 mm & in III is 8 mm, then QRS in II is 12 mm)

• aVL – points to L-arm
• aVR – points to R-arm
• aVF – points to feet

a = augmented, V = voltage
aVR = AVL + aVF = 0

• Each lead is 30° apart

Precordial System (Precordial/Chest Leads)

• Sagittal view (frontal plane)
• Perpendicular to limb leads
• 6 precordial leads: V1, V2, V3, V4 ,V5, V6 (from R => L)
• R-precordials = V1-V2 (closest to RA & RV)
• L-precordials = V5-V6 (closest to lateral wall of LV)
• Each lead is 20° apart

Lead Systems Combined

• Represents standard 12-lead ECG
• Allow for localizing pathology

Special Leads

• Right-sided leads (V3R-V6R): R-lateral view (eg, dx RV MI)
• Posterior leads (V7-V9): posterior wall view (eg, dx posterior MI)

Abbreviations: L, left; R, right; RA, right atrium; RV, right ventricle; LV, left ventricle; dx, diagnose