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Postural orthostatic tachycardia syndrome (POTS) is a condition characterized by symptoms that occur when the patient stands up from a reclining position. Upon standing, the person experiences dizziness or fainting and an excessive heart rate. Scientists don't fully understand what causes POTS, and treatments vary in effectiveness.
When a person rises from a horizontal to vertical position, gravity causes blood to move rapidly downward toward the lower body, and the heart has to compensate for this sudden shift to maintain blood pressure and supply the brain with oxygen. One of the main symptoms of postural orthostatic tachycardia syndrome is orthostatic intolerance, in which the body is unable to adequately adapt to this change and blood returns to the upper body at a significantly lower rate than it should. As a result, the flow of blood to the brain is reduced, and a person with POTS may feel lightheaded, experience blurred vision or vision spots, or faint upon standing.
In addition, a person with postural orthostatic tachycardia syndrome experiences an increase in heart rate of 30 or more additional beats per minute than normal or a persistent heart rate of more than 120 beats per minute for 10 minutes or longer after standing up. This tachycardia results from the heart trying to compensate for the low supply of blood to the brain. The sensation of a racing heart may be accompanied by sweating and feelings of anxiety.
Postural orthostatic tachycardia syndrome occurs most frequently in women, although men can also suffer from POTS. In some cases, postural orthostatic tachycardia syndrome is triggered by an event, such as a surgery, pregnancy, physical trauma, illness, or menstrual period. It may also occur independently of other conditions.
Some factors that many increase the frequency of POTS episodes include dehydration, the consumption of alcohol, sitting or standing for long periods of time, extreme heat, and medications. Increasing salt intake and maintaining adequate hydration can raise blood pressure and reduce the symptoms associated with orthostatic intolerance. Compression garments such as support hose may reduce the amount of blood that flows into the lower extremities and lessen the demands on the heart that result from standing.
Postural orthostatic tachycardia syndrome can negatively impact a person's ability to function. It can affect everything in a person's life, from work to play to family life. However, most people who suffer from POTS see a gradual improvement of their symptoms over time if they make dietary and behavioral changes.