What is Postural Orthostatic Tachycardia Syndrome?

• Postural: connected to how your body is positioned
• Orthostatic: related to standing up straight
• Tachycardia: faster than normal heartbeat
• Syndrome: a set of related health signs and symptoms

Postural Orthostatic Tachycardia Syndrome (PoTS) is a disorder that affects the nervous system. PoTS is an interesting condition, as the exact number of people affected is unknown, and the reason for how it comes about is still unclear. The main symptom of PoTS is a much faster-than-normal increase in heart rate when standing up.

Other symptoms may happen when standing up and get better when sitting or lying down, such as:¹

• Feeling dizzy or lightheaded
• Noticeable and heavy heartbeats (heart palpitations)
• Chest pain
• Shortness of breath
• shaking and sweating
• Fainting or feeling faint

PoTS is estimated to affect 0.2% of the population,² however, it is so misunderstood and under-recognised that it is incredibly likely that this number is much higher, and more common than people think.³

How PoTS affects the body

When lying down, about a quarter of our blood is located in the chest area. When we stand up quickly, a large amount of blood (500 to 1000 millilitres) of blood moves down to the veins in our legs and the abdominal area.⁴

This can make it harder for the blood to return to the heart, so if the heart does not fill up with as much blood to pump through the body, it leads to a drop in blood pressure.

Our body is very sensitive to any drastic changes, so when the blood pressure drops, sensors in our arteries detect the pressure drop and sends signals through the nerves that make the heart beat, to beat faster and tighten the blood vessels, which helps to increase blood flow back into the heart and raise the blood pressure.⁵

Usually, this temporary blood pressure change is unnoticeable; however, if the body has any issues with hormonal or nerve responses that do not respond properly, it can cause a significant drop in blood pressure after standing, as seen in people with conditions like PoTS.⁶

How PoTS is diagnosed

PoTS has very specific criteria that need to be fulfilled in order to get a diagnosis.⁷

• An increase in heart rate of at least 30 beats per minute (bpm) within 10 minutes of standing in adults; at least 40 bpm in teenagers aged 12–19
• No significant blood pressure drop (≥20 mm Hg systolic or ≥10 mm Hg diastolic) for at least 3 minutes after standing up
• Finding difficulty in standing or fainting for 6 months or more
• No obvious reasons for increased heart rate, like recent activity, diet, health conditions or medications

Even more symptoms

There have been associations that people with PoTS have a lot of sleeping issues, as they often say they feel very tired, don’t wake up refreshed after sleeping, and feel sleepy during the day and experience overexhaustion.⁸

A research study showed that PoTS patients showed more problems with sleep and feeling excessively sleepy during the day compared to healthy people. Studies have shown that people with PoTS tend to have a lower quality of life, meaning their physical and mental well-being is worse than normal. People with PoTs also share similar physical health issues with people with serious heart problems.⁹ It has been shown that people with chronic conditions such as long COVID, myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS), or joint hypermobility syndrome are more likely to get PoTS as a comorbidity.¹⁰

Potential Causes

Whilst there is no direct cause, there have been reports that PoTS can be triggered through certain events, which have been known to disrupt the nervous system, such as:¹¹

• An infection caused by bacteria or viruses (like COVID-19) 
• Stressful life experiences, such as pregnancy or surgery
• A traumatic or upsetting event

However, it's not yet fully understood how they might be connected.

Whilst we do not yet know the specific cause, what we do know is that there are many things that can make your symptoms worse, such as:¹

• Being in a warm place  
• Standing or sitting upright for a long time  
• Eating lots of processed carbohydrates like white bread  
• Not drinking enough fluids  
• Drinking alcohol  
• Resting too much  
• Doing physical activity or exercise  
• Having your menstrual period  
• Feeling stressed or worried

Many health conditions have a primary symptom of a fast heartbeat when standing up, and as a result, PoTS has many different variations that can be categorised into subtypes. 

PoTS Sub-Types

Neuropathic PoTS

Neuropathic PoTS happens when nerve signals are not as active as they should be, particularly in the legs.¹²

The most notable symptoms of this subtype are:¹³

• Loss of sweating in hands and feet
• Blood pooling
• Feet turkish bluish colour when standing or warm

Hypovolemic PoTS 

Hypovolemic PoTS happens when there is a lot less volume of blood in the body than what is considered normal.¹⁴

Symptoms associated with this subtype are:¹⁴

• Weakness
• Reduce tolerance for exercise

Hyperadrenergenic PoTS 

Hyperadrenergic PoTS is when the body is in a constant “fight or flight” mode,¹⁵ which is caused by higher levels of a type of stress hormone called norepinephrine in the blood, and so the part of the nervous system that controls your body's stress response is more active than normal.¹⁶

The main symptoms related to hyperadrenergic POTS are:¹⁷

• Higher blood pressure
• Rapid heartbeat that may be more severe than in other types
• Heart palpitations
• Feelings of anxiety, shaking, cold and sweaty hands or feet when standing up
• Migraines or severe headaches
• More frequent urination after standing upright
• Feeling sick or vomiting

These subtypes do have a lot of overlap, and it is possible for someone with PoTS to experience all the symptoms of the different subtypes and would need treatment to address all of them.

There are many different treatment options, but arguably one of the best non-pharmocological treatments of PoTS is exercise.¹⁸

Exercise as PoTS treatment

Whilst exercise has been shown to make PoTS’ symptoms worse, and is particularly difficult for those with hypervolemic PoTS, as they are intolerant to exercise, exercise can help regulate the blood flow better, and so can alleviate a lot of symptoms.¹⁹

Studies have shown that even gentle exercises, combined with salt and fluid intake,  are effective, and that patients who exercise lying down, such as rowing, swimming or exercise bike, and so are able to exercise without standing up, which could make their symptoms worse. As patients exercise over time, they get fitter and are able to increase how long and how hard they exercise until they can eventually add upright exercises.¹⁸

Other Management Strategies

In addition to exercise, there are many other treatment options, such as:¹⁸

• Sleeping in a slightly elevated position to keep blood volume higher
• Wearing compression clothes on the lower body to prevent blood pooling
• Small physical movements such as - squeezing a rubber ball, crossing the legs, tensing muscles, squatting, or controlled breathing

More research is needed through high-quality studies to confirm how well these non-drug approaches work for treating PoTS, but maintaining good health and making healthy lifestyle choices is generally encouraged, regardless if you have PoTS or not.

Summary

Postural Orthostatic Tachycardia Syndrome (PoTS) is a nervous system disorder causing an abnormal heart rate increase upon standing. Symptoms include dizziness, palpitations, chest pain, shortness of breath, sweating, fainting, and fatigue. It affects about 0.2% of the population but is likely underdiagnosed.

PoTS happens when blood moves away from the heart when standing up, making it harder for blood to return to the heart and causing blood pressure to drop. In response, the body tries to speed up the heartbeat and tighten blood vessels, but problems with nerves or hormones can interfere with this process, leading to the associated symptoms.

Diagnosis requires a heart rate increase of ≥30 bpm for adults or ≥40 bpm for teenagers within 10 minutes of standing, with no significant blood pressure drop, which has lasted for over 6 months and no other additional external factors.

Additional symptoms include sleep disturbances, fatigue, poor quality of life, and similarities to other conditions like ME or chronic fatigue. Triggers may include infections, stress, trauma, or surgery, but the causes are currently unclear. Symptoms worsen with heat, prolonged standing, poor hydration, alcohol, stress, or the menstrual cycle.

PoTS has different subtypes:

• Neuropathic: nerve issues in legs; signs include reduced sweating and blood pooling
• Hypovolemic: low blood volume; symptoms include weakness and exercise intolerance
• Hyperadrenergic: high stress hormones; symptoms include high BP, anxiety, migraines, frequent urination, and nausea

Treatment includes exercise, preferably lying down, but also lots of hydration, compression garments, and small, frequent physical movements. Further research is needed, but healthy lifestyle choices support the management of PoTS.