QRS Terminology

• < 5 mm = lower case
• r = the positive wave
• q = the negative wave before r
• s = the negative wave after r

Duration (the widest one)

< 3 mm (120 ms) - narrow

Amplitude

5 - ? (perhaps 11) mm in limb leads, 10 - 25 mm in precordial leads

Low QRS amplitude (< 10 mm)

High QRS amplitude (>25 mm)

QRS transition:

• (V5, V6): R > S (more positive)
• (V1, V2): S > R (more negative)
• (V3, V4): isoelectric

Rule:

• shift toward hypertrophy (LV, RV) → at risk of HOCM - Hypertrophic Cardiomyopathy
• shift away from scar tissue

Q wave

• Duration: 1 mm (40 ms)
• Amplitude: 25-30% of the R wave, or < 2 mm