What is Postural Orthostatic Tachycardia Syndrome?

POTS tea making marathonPostural – a position of the body

Orthostatic – caused by standing upright

Tachycardia – a rapid heartbeat

Syndrome – a group of symptoms that indicate a disease

Standing up can be a struggle for a person with POTS as your heart beats much too fast. This happens because your autonomic (involuntary) nervous system can’t adjust to the effects of gravity. Your heart-rate when standing can be 120 beats per minute or more, which reduces the blood supply to your brain.
POTS symptoms may be mild or severe but can be very disabling, similar to conditions like heart failure or pulmonary disease. People with POTS often experience tachycardia, fainting, fatigue, headaches, poor concentration and chest pains. So many people with POTS are unable to work with limited quality of life.
POTS is often a secondary condition, which means it is a consequence of another condition, such as diabetes, amyloidosis, sarcoidosis, multiple sclerosis or Ehlers Danlos Syndrome Hypermobility type.  It can be caused by deconditioning, for example after prolonged bed rest due to an illness. It could follow an infection, pregnancy, or an accident such as a whiplash injury. When POTS is the primary condition the cause is unknown. Sometimes POTS runs in families, so it may be an inherited condition.
How the condition progresses depends what has caused it. POTS can occur in teenagers during a growth spurt, but then disappear after a few years. Symptoms can last just a few weeks after a viral infection, or for many years. When POTS is caused by Ehlers Danlos Syndrome Hypermobility type symptoms come on earlier in life and are lifelong. Changes in your lifestyle and a number of medications have been proven to help POTS symptoms and most people respond to treatment. (ref).

The Autonomic Nervous System

The autonomic (involuntary) nervous system controls bodily functions that we do not have to think about, such as breathing, digestive function, sweating, blood pressure and heart rate. POTS is caused by abnormal functioning of the autonomic nervous system, often called ‘dysautonomia’.
When a person unaffected by POTS stands up, up to 800 mls of their blood will drop into their chest, hands and feet due to gravity. To maintain blood supply to the brain and prevent blood pressure from dropping, blood vessels narrow and heart rate increases slightly (10-15 bpm). But in someone with POTS, the autonomic nervous system doesn’t function correctly and not enough blood is supplied to the heart and brain. Their heart rate rises sharply (30 beats per minute or more within 10 minutes) and excess adrenaline may be produced to compensate.
A Tilt Table

A Tilt Table

Around 30% of people with POTS have been found to also have Ehlers Danlos Syndrome Hypermobility type (ref). It seems likely Ehlers Danlos Syndrome is the cause of the POTS symptoms as weak and stretchy connective tissue in their blood vessels allows them to expand under pressure from gravity rather than narrow (ref). Blood sinks into the legs and heart rate rises sharply to try to maintain blood supply to the brain. These people appear to develop POTS earlier in life and pass out more frequently. (ref).
A tilt table can be used to test for POTS. As the tilt table is raised, blood pressure and heart rate monitors record how the heart and circulation react to moving from a horizontal to vertical position.
( UPDATE: This page was written in the autumn of 2014. – At a hospital appointment in March 2015 I was told that current figures suggest 80-90% of cases of POTS are caused by Ehlers Danlos Syndrome Hypermobility type. Previously the figure was thought to be about 30%. This is very recent research. The source is obviously credible however there is currently no documentation online I can link to to support the statistic. )

Symptoms of Postural Orthostatic Tachycardia Syndrome can include:

  • Tachycardia (rapid heart beat). (ref).
  • Palpitations (your heart feels like it is pounding, fluttering or beating irregularly).
  • A Tilt Test Reading. - Click to Enlarge.

    A Tilt Test Reading. – Click to Enlarge.

    Dizziness (ref) and syncope (fainting).
  • Poor concentration, a symptom known as ‘brain fog’. (ref).
  • Headaches.
  • Chronic fatigue. (ref) (ref) (ref).
  • Anxiety (ref).
  • Exercise intolerance. (ref).
  • Digestive discomfort (ref) (ref).
  • Sweating.
  • Tremor / shakiness.

Lifestyle Changes that Help POTS

If you think you may have POTS you must consult a doctor before trying any treatments. You could consider:
  • A high fluid intake, 2 litres a day.
  • Regular Exercise. (ref) (ref).
  • Small Frequent Meals.

Things to Avoid

  • Dehydration (too little intake of fluid) reduces blood volume.
  • Heat and alcohol, which both dilate blood vessels.
  • Heavy meals, which divert blood away from the brain to the gut.
  • Excess standing and sitting.

Medications that help POTS

There are three main methods of treating POTS: by increasing blood volume, constricting blood vessels, and lowering heart rate. Sometimes these methods are used in combination. People with POTS can be sensitive to medications and are usually started on low doses. Side effects need to be monitored carefully.
Increasing Blood Volume
  • Fludrocortisone, which is a corticosteroid that increases salt levels in the body to retain fluid. Potassium levels need to be monitored.
  • Desmopressin, which is a hormone that reduces urine production increasing fluid retention. (ref).
  • Erythropoietin, which increases the production of red blood cells and so increases blood volume. It also constricts blood vessels.
Constricting Blood Vessels
  • Midadrine, which aims to increase the return of blood to the heart. (ref). Ephedrine was formerly used for this role.
  • Octreotide, which prevents vasodilation in the gut reducing the drop in blood pressure after eating. (ref).
Lowering Heart Rate
  • Beta blockers, such as Propanolol (ref) (ref) or Bisoprolol.
  • Ivabradine (ref) (ref).
Other Medications:
  • Pyridostigmine, which acts on the junctions between nerves. (ref).
  • Modafinil, which is a stimulant used for sleep disorders, but may improve mental clouding (brain fog). However it could increase tachycardia.
  • SSRIs & SNRIs (Selective Serotonin Reuptake Inhibitor & Serotonin Noradrenaline Reuptake Inhibitor). – These drugs are intended to treat anxiety and depression. However some research has shown serotonin plays a part in the autonomic regulation of both blood pressure and heart rate, so these drugs may be useful in treating POTS. Some people have reported improvement when used alongside more traditional POTS treatments. But how they work remains unclear, and their benefit remains unproven. (ref).

 

Stickman image used under license from Stickman Communications.