Sinus rhythm with resting heart rate (HR) > 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
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.
- Hypoxia, hypercarbia
- Sepsis, pyrexia
- Pulmonary embolism
- Cardiac tamponade
- Alcohol withdrawal
- Beta-agonists: adrenaline, isoprenaline, salbutamol, dobutamine
- Sympathomimetics: amphetamines, cocaine, methylphenidate
- Antimuscarinics: antihistamines, TCAs, carbamazepine, atropine
- Others: caffeine, theophylline, marijuana
- Heart rate 150 bpm.
- P waves are hidden within each preceding T wave.
With very fast heart rates the P waves may be hidden in the preceding T wave, producing a ‘camel hump’ appearance.
- Wiesbauer F, Kühn P. ECG Yellow Belt online course: Become an ECG expert. Medmastery
- Wiesbauer F, Kühn P. ECG Blue Belt online course: Learn to diagnose any rhythm problem. Medmastery
- Rawshani A. Clinical ECG Interpretation ECG Waves
- Smith SW. Dr Smith’s ECG blog.
- Mattu A, Tabas JA, Brady WJ. Electrocardiography in Emergency, Acute, and Critical Care. 2e, 2019
- Brady WJ, Lipinski MJ et al. Electrocardiogram in Clinical Medicine. 1e, 2020
- Straus DG, Schocken DD. Marriott’s Practical Electrocardiography 13e, 2021
- Hampton J. The ECG Made Practical 7e, 2019
- Grauer K. ECG Pocket Brain (Expanded) 6e, 2014
- Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography 1e, 2009
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric 6e, 2008
- Mattu A, Brady W. ECG’s for the Emergency Physician Part I 1e, 2003 and Part II
- 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