Sinus Tachycardia

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This is part of: Supraventricular Rhythms
Sinustachycardia
Rhythm tachycardia.png
Atrial rate 100-180 bpm
Ventricular rate same
Regularity {{{regularity}}}
Origin sinus node
P-wave positive in II, AVF
Effect of adenosine no (can lead to temporary AV block)
Example ECG:
Example ECG2: {{{example2}}}
An example of sinustachycardia

Sinus tachycardia is sinus rhythm with a rate of > 100bpm. Sinus tachycardia is an example of a supraventricular rhythm. In sinus tachycardia the sinus node fires between 100 and 180 beats per minute, faster than normal. The maximal heart rate decreases with age from around 200 bpm to 140 bpm. The maximal heart rate can be estimated by subtracting the age in years from 210. Sinus tachycardia normally has a gradual start and ending. Most often sinus tachycardia is caused by an increase in the body's demand for oxygen, such as during exercise, stress, infection, blood loss and hyperthyroidism. It can also express an effort of the heart to compensate for a reduced stroke volume, as occurs during cardiomyopathy.

The maximal heart rate is considered to be 220/min minus the age (or more precisely 207-0.7xAge [1][2]). However, this is often exceeded during vigorous exercise and has a large inter-individual variation.

Appropriate sinus tachycardia can result from: [3]

  • Exercise
  • Anxiety
  • Alcohol / caffeine use
  • Drugs (e.g. beta-agonists like dobutamine)

Inappropriate sinus tachycardia can result from:

  • Fever
  • Hypotension
  • Hypoxia
  • Congestive heart failure
  • Bleeding
  • Anemia
  • Hyperthyroidism
  • Cardiomyopathy (with reduced left ventricular function and compensatory tachycardia)
  • Myocarditis

Inappropiate sinus tachycardia is rare and characterized by tachycardia at rest and exaggerated acceleration of the heart during physiologic stress. The mechanism leading to an exaggerated response of the sinus node to minimal physiologic stress is incompletely understood.

References

  1. Tanaka H, Monahan KD, and Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol 2001 Jan; 37(1) 153-6. pmid:11153730. PubMed
  2. Robergs and Landwehr. The Surprising History of the “HRmax=220-age” Equation. Journal of Exercise Physiology online. 2 May 2002

  3. Borys Surawicz, Timothy Knilans. Chou's electrocardiography in clinical practice. Philadelphia: Saunders, 2001. isbn:9780721686974.