Sinus · Stable
Normal Sinus Rhythm
● Live · lead II25 mm/s · 10 mm/mV
II
10-second rhythm strip · count the boxes
Rate60–100 bpm
RegularityRegular
P wavesUpright in II, one before every QRS, uniform
PR interval0.12–0.20 s, constant
QRS< 0.12 s (narrow)
Key features
- Every P is followed by a QRS, every QRS preceded by a P
- P waves upright in I, II, aVF; inverted in aVR
- R-R intervals vary < 10%