Sinus tachycardia


  • Sinus rhythm with a resting heart rate of > 100 bpm in adults, or above the normal range for age in children.

Normal heart rates in children

  • Newborn: 110 – 150 bpm
  • 2 years: 85 – 125 bpm
  • 4 years: 75 – 115 bpm
  • 6 years+: 60 – 100 bpm




  • Beta-agonists: adrenaline, isoprenaline, salbutamol, dobutamine
  • Sympathomimetics:  amphetamines, cocaine, methylphenidate
  • Antimuscarinics:  antihistamines, TCAs, carbamazepine, atropine
  • Others: caffeine, theophylline, marijuana

 Handy Tip

With very fast heart rates the P waves may be hidden in the preceding T wave, producing a ‘camel hump’ appearance.

Hidden P waves in sinus tachycardia ("camel hump" appearance)


Example ECG

Sinus tachycardia:

  • Heart rate 150 bpm.
  • P waves are hidden within each preceding T wave.


Related Topics

Further Reading

Author Credits


  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.
  • Surawicz B, Knilans TK. Chou’s Electrocardiography in Clinical Practice. 6th Edition. Saunders Elsevier 2008.
Print Friendly