1. Normal Sinus Rhythm

2. Normal Sinus Rhythm
• Description
– The sinus node is the pacemaker, firing at a
regular rate of 60 to 100 times per minute
• Conduction
– Each impulse follows the normal pathway of
conduction resulting in atrial and ventricular
depolarization

3. Normal Sinus Rhythm
• Normal sinus rhythm is the standard against
which all other rhythms are compared

4. Normal Sinus Rhythm
RATE RHYTHM P WAVE PR INTERVAL QRS
60-100 Regular Upright 0.12-0.20 0.11 or less

5. Normal Sinus Rhythm
• Atrial and ventricular rhythms are regular
• Atrial and ventricular rates fall between 60
and 100 beats/minute
– The SA node’s normal firing rate and all impulses
are conducted to the ventricles

6. Normal Sinus Rhythm
• P waves are rounded, smooth, and upright in
lead II, signaling that a sinus impulse has
reached the atria

7. Normal Sinus Rhythm
• PR interval is normal indicating that the
impulse is following normal conduction
pathways
– 0.12-0.20 seconds

8. Normal Sinus Rhythm
• The QRS complex is of normal duration
representing normal ventricular impulse
conduction and recovery
– Less than 0.12 seconds

9. Normal Sinus Rhythm
• The T wave is upright in lead II, confirming
that normal repolarization has taken place

10. Normal Sinus Rhythm
• The QT interval is within normal limits
– 0.36 to 0.44 seconds

11. Normal Sinus Rhythm
• No ectopic or aberrant beats occur

12. Normal Sinus Rhythm
• Characteristics of normal sinus rhythm
– Regular rhythm
– Normal rate
– A P wave for every QRS complex and all P waves
similar in size and shape
– All QRS complexes similar in size and shape
– Normal PR and QT intervals
– Normal (upright and round) T waves

13. Review
• Normal Sinus Rhythm
– P wave
– PR interval
– QRS complex
– ST segment
– T wave
– QT interval
– Normal U wave

14. NS Rhythm Review
• Normal P wave
– Before the QRS
– 0.06 to 0.12 second
– Usually rounded and upright

15. NS Rhythm Review
• Normal PR interval
– From the beginning of the P wave to the beginning
of the QRS complex
– 0.12 to 0.20 second

16. NS Rhythm Review
• Normal QRS complex
– Follows the PR interval
– 0.06 to 0.10 second
– Consists of the Q wave, the R wave, and the S
wave

17. NS Rhythm Review
• Normal ST segment
– From the S wave to the beginning of the T wave

18. NS Rhythm Review
• Normal T wave
– After the S wave
– Typically round and smooth

19. NS Rhythm Review
• Normal QT interval
– From the beginning of the QRS complex to the
end of the T wave
– Usually lasts from 0.36 to 0.44 second

20. NS Rhythm Review
• Normal U wave
– After T wave
– Typically upright and rounded

21. NS Rhythm Review
• Determine the rhythm
• Determine the rate
• Evaluate the P wave
• Measure the PR interval
• Determine the QRS complex duration
• Examine the T waves
• Measure the QT interval duration
• Check for ectopic beats and other abnormalities