Postural Orthostatic tachycardia syndrome is an abnormality of the functioning of the autonomic (involuntary) nervous system, often referred to as dysautonomia. Essentially the autonomic nervous system is everything your body should do without thinking.
To be diagnosed with PoTS, a person must experience a group of symptoms in the upright position (usually standing) that are relieved by lying down. A persistent increase in heart rate of 30 beats per minute or greater (40 bpm if under 19 years of age) should be recorded within ten minutes of standing. Blood pressure does not always drop in POTS.
The autonomic nervous system (ANS) is in charge of all bodily functions that we don’t have to think about, such as:
- Heart rate and blood pressure regulation
- Bladder control
- Stress response
The sympathetic nervous system is part of the autonomic nervous system. It produces the ‘fight or flight’ or ‘stress’ response. When activated, a chemical called norepinephrine is released. Amongst other things, this causes an increase in heart rate and blood pressure.
What should happen to my blood when I stand up?
Orthostatic intolerance: is a term that is sometimes used to describe symptoms of POTS. It means symptoms that occur on standing and are relieved by lying down. In addition to heart rate and blood pressure, other bodily functions that are regulated by the autonomic nervous system can be affected.
Symptoms can be debilitating, ranging from mild to severe and varying from day to day.
- Dizziness or light-headedness or presyncope (almost fainting). These symptoms usually occur when standing up, but can occur with prolonged sitting.
- Syncope (fainting or blackouts). It is estimated that 30 % of people with PoTS experience fainting.
- Palpitations. Palpitations are a sensation of your heart pounding in your chest.
- Headaches. A large proportion of people with POTS have orthostatic headaches which means they occur as a result of being upright and may be caused by reduced blood supply to the brain. Most people with POTS also have migraine type headaches.
- Fatigue or weakness. These are common symptoms of POTS and can last for a considerable time after a bout of symptoms of POTS.
- Brain fog. People with POTS often complain of ‘brain fog’ which is difficulty in thinking or concentrating.
- Shakiness or Tremulousness. This is often worse with upright posture
- Shortness of breath. Patients can feel breathless when standing up or with slight exertion.
- Chest pain. Chest pain is fairly common in patients and can be worse when upright.
- Excessive or patchy reduced sweating
- Gut problems. Nausea is common. Other symptoms include diarrhoea, constipation, bloating, abdominal pain and vomiting.
- Poor sleep. Many patients with POTS have insomnia. This can be trouble getting to sleep, waking in the middle of the night and trouble getting back to sleep.
- Visual problems. This can be described as excessive glare, blurred or tunnel vision.
- Bladder problems
Triggers which may worsen symptoms
- Excess heat
- After eating – especially refined carbohydrate eg sugar, white flour
- Speed of positional change – don’t stand up quickly
- Time of day (may be worse in the morning, especially rising after wakening)
- Menstrual period
- Deconditioning or prolonged bed rest
- Alcohol which dilates blood vessels
How is POTS diagnosed?
Patients are usually diagnosed by a cardiologist or neurologist.
To be given a diagnosis of POTS, a person needs to have:
- A sustained increase in heart rate of greater than 30 beats per minute within 10 minutes of standing
- Those aged 12-19 years require an increase of at least 40 beats per minute
- These criteria may not apply to those with a low heart rate when resting
- There is usually no drop in blood pressure on standing
An ECG is performed to rule out any heart problems that may cause symptoms similar to those found in POTS.
The Active Stand Test
The active stand test can be used to diagnose PoTS. Under careful supervision, heart rate and blood pressure are measured after resting lying down, then immediately upon standing and after 2, 5 and 10 minutes. This test may bring on symptoms of POTS and some people may faint.
Head-Up Tilt Table Test
This involves lying on a table that can be tilted to an angle of 60 to 70 degrees in a quiet, dimly lit, temperature controlled room. Blood pressure and heart rate are recorded in a continuous manner. After a period of 5 to 20 minutes of lying flat, the table is tilted. Although a diagnosis of POTS should be made by an increase in heart rate of 30 bpm within the first 10 minutes, this upright position can last between 10 and 45 minutes. The patient will be asked how they are feeling during the test, so symptoms can be matched with heart rate and blood pressure. The test will end if your blood pressure becomes too low, satisfactory results have been obtained, or the maximum time has elapsed.
For further information on POTS head over to POTS UK, an informative and supportive site whereby you can also read patient stories.
*Throughout my blog I will be writing much more about POTS from my experiences of living with the condition, testing and what I find helps and hinders. Articles on POTS will be easily accessible from the category section in the sidebar*