Sinus tachycardia

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.

Differential Diagnosis

• 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