Sinus tachycardia

Definition

• 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

Causes

Non-pharmacological

• Exercise
• Pain, anxiety
• Hypoxia, hypercarbia
• Acidaemia
• Sepsis, pyrexia
• Pulmonary embolism
• Hyperthyroidism

Pharmacological

• 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.

 

Example ECG

Sinus tachycardia:

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

 

Related Topics

• Sinus rhythm
• Sinus arrhythmia
• Sinus bradycardia

Further Reading

• ECG BASICS – Waves, Intervals, Segments and Clinical Interpretation
• ECG CLINICAL CASES – Your favourite ECG’s placed in clinical context with a challenging Q&A approach
• ECG and Cardiology Eponymous Syndromes – Cheats guide to eponymous emancipation
• ECG Reference Sites on the WEB – the best of the rest

Author Credits

References

• 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.