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Sinustachycardia is [[Sinus_node_rhythms_and_arrhythmias|sinus rhythm]] with a rate of > 100bpm. Sinustachycardia is an examples of a [[Supraventricular Rhythms|supraventricular rhythm]].In sinustachycardia the sinus node fires between 100 and 180 beats per minute and thus faster than normally. The maximal heartrate decreases with age from around 200 bpm to 140 bpm. The maximal heartrage can be estimated by subtracting the age in years from 210. Sinustachycardia normally has a gradual start and ending. Most often sinustachycardia 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 cardiomyopaty. Appropiate sinustachycardia can result from: <cite>Surawicz</cite>* exercise* anxiety* alcohol / caffeine use* drugs (e.g. beta-agonists like dobutamine) The following disease states can result in sinustachycardia:* fever* hypotension* hypoxia* congestive heart failure* bleeding* anemia* hyperthyroidism* cardiomyopathy (with reduced left ventricular function and compensatory tachycardia)* myocarditis
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The maximal heart rate is considered to be 220/min minus the age (or more precisely 207-0.7xAge <cite>Tanaka</cite><cite>Robergs</cite>). However this is often exceeded during vigorous exercise and has a large inter-individual variation.
Inappropiate sinustachycardia 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.