Sinus Rhythm

Normal Sinus Rhythm

Heart Rate: 60-100 bpm
Rhythm: Essentially regular
Pacemaker Site: Sino-Atrial Node (SA Node)
P Waves: Upright in Lead II, identical and precedes each QRS complex.
PR Interval: Normal (0.12-0.20 seconds which equates to 3-5 small squares on standard ECG paper).