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Dysautonomia refers to a disorder of the autonomic nervous system (ANS)--the main bodily system that controls organ function and involuntary actions of the body. The ANS controls heart rate, blood pressure, temperature, digestion, salivation, perspiration, pupil dilation/constriction, and other functions. Because of the wide range of functions controlled by the ANS, dysautonomia often leads to multiple symptoms throughout the body, some of which can be quite debilitating.

Postural Orthostatic Tachycardia Syndrome (POTS)

This condition is a type of dysautonomia. Normally, when a person stands, gravity pulls blood to the lower extremities. The nervous system senses this and sends a message to the blood vessels in the legs to constrict, sending more blood back to the heart and the head. In patients with POTS, this message to constrict the blood vessels does not get sent. Therefore, instead of the heart rate increasing by a normal 10 to 15 beats per minute upon standing, it increases by more than 30 beats and can even double.

By affecting circulation, it also affects cerebral blood flow. Patients with POTS may not be able to sustain sitting or standing for a long period of time, as this will affect their circulation. They will not be able to maintain that posture without feeling dizzy, lightheaded, and may even faint.  On any given day they may experience the following symptoms:

  • Orthostatic Intolerance (lightheadedness, dizziness)
  • Chest pain
  • Headaches
  • Gastrointestinal cramps
  • Inability to focus and concentrate for long periods
  • Inability to read due to blurred vision
  • Difficulty with recall
  • Extreme fatigue
  • Nausea
  • Exercise Intolerance
  • Tremulousness
  • Appetite Disturbance
  • Insomnia

Neurally Mediated Hypotension (NMH)

Neurally Mediated Hypotension (NMH) occurs when peripheral blood vessels become dilated, causing low blood pressure (hypotension) and slowed heart rate (bradycardia). If severe enough NMH can lead to a loss of consciousness, or syncope. It is one of the most common causes of fainting.


  • Lightheadedness
  • Fainting
  • Prolonged fatigue after modest physical activity
  • Muscle aches
  • Headaches
  • Brain fog or mental confusion




Additional information can be found at the Dysautonomia Information Network (DINET).

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Children's Heart Institute

P. O. Box 10066 McLean, VA 22102

Central Registration (patient appointments):

phone - 703-481-5801

Billing Inquiries:

phone - 571-612-2600 /  fax - 571-266-4096