• Main Ventricular Vector and Ventricular Hypertrophy
• ECG and Left Ventricular Hypertrophy
• ECG and Right Ventricular Hypertrophy
• ECG and Biventricular Hypertrophy

Main Ventricular Vector and Ventricular Hypertrophy

• The main ventricular vector is best observed
• Chest leads (V1 and V6)
• Ventricular hypertrophy is visible on the ECG
• Best seen in leads (V1 and V6)
  
  
• Left Ventricular Hypertrophy (LVH)
• The cardiac vector rotates in the direction of LV hypertrophy
• Because the LV is enlarged
• The vector points almost directly
• towards lead V6
• away from lead V1
• thus resulting in larger QRS complex amplitudes
  
  
• Right Ventricular Hypertrophy (RVH)
• The cardiac vector rotates in the direction of RV hypertrophy
• The vector is smaller because the RV is smaller than the LV
• The vector points almost directly
• towards lead V1
• away from lead V6
• QRS amplitudes will be smaller

ECG and Right Ventricular Hypertrophy

• ECG does not differentiate
• concentric hypertrophy from eccentric hypertrophy
  
  
• The primary ECG marker for Right Ventricular Hypertrophy (RVH) is:
• Dominant R wave (V1) ≥ 7mm (R/S ratio (V1) ≥ 1)

Biventricular Hypertrophy

• Left Ventricular Hypertrophy
• Positive voltage criteria: (V2(S) + V5(R) = 35 mm, aVL(R) > 11 mm)
• Overloaded left ventricle (negative T waves in V4-V6)
• Katz Wachtel phenomenon
• Large bifasic QRS complexes (V2-V5)
• Deep S waves (V5-V6)
• Indicates concurrent right ventricular hypertrophy

Biventricular Hypertrophy

• This is an ECG from a child with a ventricular-septal defect
• Sinus Tachycardia
• Katz Wachtel phenomenon
• Large bifasic QRS complexes (V2-V5)
• Gigantic QRS > 50mm (V2)
• Right Axis Deviation