Introduction

What is postural orthostatic tachycardia syndrome?

Postural orthostatic tachycardia syndrome (POTS) is a chronic health condition. Its name is composed of several medical terms which, when broken down, can reveal its nature.

• Postural – position of the body
• Orthostatic – an upright posture
• Tachycardia – fast heart rate
• Syndrome – a combination of symptoms

Therefore, POTS is a disorder characterised by orthostatic intolerance, or an inability to withstand an upright posture due to the symptoms this causes, such as an increase in heart rate.

POTS is a complex disorder and can affect many systems in the body, causing an array of symptoms that can often be debilitating and could affect your ability to carry out simple daily activities.^1,2

What is the autonomic nervous system?

The autonomic nervous system is a subdivision of our nervous system. It is responsible for regulating body functions that we do not consciously control or have to think about. Examples of these involuntary processes include:

• Regulation of heart rate and blood pressure
• Digestion
• Bladder control
• Sweating
• The stress response

If you have POTS, your autonomic nervous system does not work properly. This is also referred to as ‘dysautonomia’. 

Types of POTS

POTS can be characterised into several subtypes as described below:

What happens in POTS?

In healthy individuals, blood vessels narrow and heart rate increases slightly when you sit or stand up so that blood supply to the brain can be maintained

If you have POTS, you’ll find it hard to coordinate this narrowing of blood vessels and change in heart rate. This means that when you assume an upright posture, blood vessels do not tighten enough to ensure there is adequate blood flow to the brain – blood tends to pool at your feet instead, causing you to feel dizzy. You could also experience an excessive increase in heart rate as your heart tries to quickly pump blood to the brain to compensate for this poor circulation. This excessive heart rate is called tachycardia.

Is POTS an autoimmune condition?

Autoimmune conditions are characterised by the immune system mounting an attack against its own healthy cells, causing certain symptoms as a result of the production of autoantibodies.

It is believed that people with POTS have increased levels of auto-antibodies. Okamoto and team identified high levels of a pro-inflammatory (capable of promoting inflammation)molecule called interleukin 6 (IL-6) in POTS patients, which is associated with increased activation of the immune system.⁴ These results raise the question of whether POTS should be classified as an autoimmune condition since it shares characteristics with conditions already categorised under this term.

Symptoms of POTS

The key symptoms of POTS include dizziness and lightheadedness, which may lead to fainting or blackouts, although this is not always the case in every person with POTS. Palpitations are also extremely common, and you may notice a pounding sensation in your chest or feel like your heart is skipping a beat. Other cardiac symptoms could include chest pain which usually worsens when upright, and shortness of breath following slight exertion or when standing up.

However, POTS is a systemic disorder and affects other parts of your body too. Indeed, to fulfil the diagnostic criteria of POTS you will likely experience additional symptoms other than dizziness and palpitations upon sitting or standing. Symptoms may include: 

• Neurological
  • Dizziness and lightheadedness
  • Brain fog
  • Headaches
  • Insomnia
  • Blurred vision
• Cardiac
  • Palpitations, tachycardia
  • Chest pain
  • Shortness of breath
• Gastrointestinal
  • Bloating
  • Nausea
  • Abdominal pain
  • Vomiting
  • Constipation
  • Diarrhoea
• Urogenital
  • Bladder dysfunction
  • Increased urgency and frequency
• Other
  • Peripheral acrocyanosis or ‘POTS feet’
  • Raynaud’s phenomenon

Furthermore, POTS is a chronic disorder, meaning that your symptoms will typically persist for several months. ^1,2

Figure 1. Symptoms of POTS, including Raynaud’s phenomenon and peripheral acrocyanosis.

Other general symptoms of POTS

• Shaking and weakness
• Excessive sweating
• Feeling cold easily and being unable to tolerate heat
• Fibromyalgia
• Fatigue and generally feeling unwell – many patients with POTS have also been diagnosed with chronic fatigue syndrome^1,5,6

Causes of POTS

• Life stressors – events like pregnancy, surgery, immunisation and trauma may cause POTS
• Previous infections – POTS may develop after an illness such as Lyme disease or glandular fever
• Secondary causes – these include conditions that occur alongside POTS like Ehlers-Danlos syndrome or mast cell activation syndrome ⁷
• Genetic factors – you may have a genetic mutation affecting autonomic function, predisposing you to POTS ¹

It is also important to note that the cause of POTS may be unknown, and your doctor may be unable to identify the clear cause of your symptoms.

Exacerbating factors

You may notice the severity of your symptoms fluctuate depending on certain factors. Triggers for a worsening of your symptoms could include:

• Being in a hot environment
• Dehydration
• Prolonged bed rest
• Menstruation
• Eating – this specifically includes carbohydrate-heavy meals
• Drinking alcohol – this widens your blood vessels, causing you to feel dizzy and lightheaded
• Exercise – this includes exercise of high intensity or any activity that requires quick changes in posture such as squats¹

FAQs

How common is POTS and who can it affect?

Population studies estimate that 0.2-1% of the general population have POTS. It is possible for anyone to be diagnosed with the condition, although it primarily affects Caucasian females aged between 15 and 45 years. Symptoms usually first present between 15 and 25 years of age.

Is POTS a heart condition?

Although POTS causes symptoms related to the heart, like palpitations and chest pain, the structure and health of the heart is normal in people with POTS. Instead, POTS is a condition originating in poor blood circulation and a problem with your autonomic nervous system.  

Can I recover from POTS?

Currently, there is no cure for POTS but with correct treatment and lifestyle changes, many patients find their symptoms improve and may even disappear altogether, allowing them to have as good a quality of life as possible.

What happens if POTS is left untreated?

If your POTS symptoms are not effectively managed you may become less active and could spend prolonged amounts of time resting. This could lead to complications such as reduced muscle mass, causing your heart to become weak over time. If the condition causes you to frequently faint, you may also sustain damage from repeated falls. 

Summary

POTS is a disorder of the autonomic nervous system with key symptoms including dizziness and heart palpitations. These occur because when you move into an upright posture, blood vessels do not constrict enough to ensure that there is sufficient blood flow to the brain, causing you to feel dizzy. You could also experience an excessive increase in heart rate as your heart tries to quickly pump blood to the brain to compensate.

The condition also affects many other systems in the body and can cause an array of other problems like headaches, nausea and bladder dysfunction. There are several types of POTS, including neuropathic, hyperadrenergic and hypovolaemic – POTS may also occur secondary to other conditions. A stressful life event can cause POTS or it may follow an illness like glandular fever. Several factors are known to worsen POTS, such as being too hot, dehydration, and alcohol, so it is important to avoid these triggers where possible to help manage your symptoms.