Postural Orthostatic Tachycardia Syndrome

**Definition:** A syndrome of ORTHOSTATIC INTOLERANCE combined with excessive upright TACHYCARDIA, and usually without associated ORTHOSTATIC HYPOTENSION. All variants have in common an excessively reduced venous return to the heart (central HYPOVOLEMIA) while upright.

**Tree numbers:** - C10.177.575.600.625

**Synonyms:** - Postural Tachycardia Syndrome