Background

A cardiac abnormality characterized by the presence of a sinus rhythm at a rate that is above the upper limit of normal.
- In adults, usually defined as a heart rate >100. In pediatric patients it varies by age. See pediatric vital signs.
Usually a secondary response to another medical condition.

Evaluation

History and physical exam, focusing on any evidence of intoxication, infection, dehydration, or a psychiatric/emotional state that may contribute to an elevated heart rate. Orthostatic vital signs should be measured.
EKG should be ordered to rule out other arrhythmias that may present with an elevated heart rate.
If history and physical are unable to explain the tachycardia, limited labs and imaging studies may be indicated.
- CBC, BMP, UTox, UA, TSH, troponin, and CXR are often indicated.
- If suspected, a CT of the pulmonary arteries, may be able to diagnose a PE.

Emotional or psychiatric causes such as pain, anger, or anxiety
Appropriate response to fever (about 10 bpm per degree C > 37.0)
SIRS (from infection or other causes)
Dehydration
Anemia
Drug/alcohol intoxication (particularly sympathomimetic or anticholinergic drugs, but may also be seen in aspirin, theophylline, or other ingestions)
Drug/alcohol withdrawal
Anion gap acidosis
Hyperthyroidism
PE
CHF
Cardiac tamponade
Myocardial contusion
Cardiac valvular disease
Hyper or hypoglycemia
Myocardial infarction
Pheochromocytoma

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