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
- aVL – points to L-arm
- aVR – points to R-arm
- aVF – points to feet
- Each lead is 30° apart
Note: I + III = II (eg, if QRS in I is 4 mm & in III is 8 mm, then QRS in II is 12 mm)
a = augmented, V = voltage
aVR = AVL + aVF = 0
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