Sinus tachycardia

Definition

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

Sinus tachycardia is usually a secondary condition. Inappropriate sinus tachycardia is a primary condition diagnosed in patients with symptomatic persisting sinus tachycardia in which the below causes have been excluded.

Non-pharmacological

• Exercise
• Pain
• Anxiety
• Hypovolaemia
• Hypoxia, hypercarbia
• Acidaemia
• Sepsis, pyrexia
• Anaemia
• Pulmonary embolism
• Cardiac tamponade
• Hyperthyroidism
• Alcohol withdrawal

Pharmacological

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

Example ECG

Sinus tachycardia:

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

Handy Tip

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

Related Topics

• Inappropriate sinus tachycardia
• Sinus rhythm
• Sinus arrhythmia
• Sinus bradycardia

Advanced Reading

Online

• Wiesbauer F, Kühn P. ECG Mastery: Yellow Belt online course. Understand ECG basics. Medmastery
• Wiesbauer F, Kühn P. ECG Mastery: Blue Belt online course: Become an ECG expert. Medmastery
• Kühn P, Houghton A. ECG Mastery: Black Belt Workshop. Advanced ECG interpretation. Medmastery
• Rawshani A. Clinical ECG Interpretation ECG Waves
• Smith SW. Dr Smith’s ECG blog.

Textbooks

• Zimmerman FH. ECG Core Curriculum. 2023
• Mattu A, Berberian J, Brady WJ. Emergency ECGs: Case-Based Review and Interpretations, 2022
• Straus DG, Schocken DD. Marriott’s Practical Electrocardiography 13e, 2021
• Brady WJ, Lipinski MJ et al. Electrocardiogram in Clinical Medicine. 1e, 2020
• Mattu A, Tabas JA, Brady WJ. Electrocardiography in Emergency, Acute, and Critical Care. 2e, 2019
• Hampton J, Adlam D. The ECG Made Practical 7e, 2019
• Kühn P, Lang C, Wiesbauer F. ECG Mastery: The Simplest Way to Learn the ECG. 2015
• Grauer K. ECG Pocket Brain (Expanded) 6e, 2014
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric 6e, 2008
• Chan TC. ECG in Emergency Medicine and Acute Care 1e, 2004

LITFL Further Reading

• ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
• ECG A to Z by diagnosis – ECG interpretation in clinical context
• ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
• 100 ECG Quiz – Self-assessment tool for examination practice
• ECG Reference SITES and BOOKS – the best of the rest