inappropriate sinus tachycardia
A condition characterized by an abnormally elevated resting heart rate or excessive heart rate response to minimal exertion from the sinus node.
Full Definition
Inappropriate sinus tachycardia (IST) is a disorder of sinus node function characterized by an elevated resting heart rate (typically >100 bpm) or an exaggerated chronotropic response to physical or emotional stress that is out of proportion to physiologic demand. The rhythm originates normally from the sinus node but occurs at inappropriate rates for the level of activity or stress. Patients often experience symptoms including palpitations, exercise intolerance, fatigue, and chest discomfort. The condition predominantly affects young women and may be related to enhanced automaticity of the sinus node, increased sympathetic tone, or decreased parasympathetic tone. Diagnosis requires documentation of sinus tachycardia in the absence of identifiable secondary causes.
Usage
Usage note: Emphasize exclusion of secondary causes; distinguish from physiologic sinus tachycardia.
In Context
- "The patient was diagnosed with inappropriate sinus tachycardia after extensive evaluation ruled out secondary causes." — Cardiology consultation
- "Beta-blocker therapy was initiated for symptomatic inappropriate sinus tachycardia." — Treatment plan