Postural Orthostatic Tachycardia Syndrome

What is Postural Orthostatic Tachycardia Syndrome?

Postural orthostatic tachycardia syndrome (also known as POTS) is a dysfunction of the autonomic nervous system. This is the part of the nervous system that controls and regulates functions in the body that we cannot consciously influence, such as digestion, heartbeat, blood pressure, sweating, and breathing.

The two key components of POTS include:

1. Orthostatic intolerance – intolerance to standing up. The body responds abnormally to the upright position.

2. Tachycardia – an exaggerated increase of heart rate that occurs within the first 10 minutes of standing.

When a healthy person stands up, the blood vessels in the lower half of the body tighten, and the heart beats faster, in order to push blood up to the heart and brain against gravity. In POTS, the blood vessels do not tighten up enough so the blood tends to pull in the lower half of the body. This means that blood that is meant to get back to your heart and the upper body, stays in the legs. As compensation, the brain tells the heart to beat harder and faster.

Symptoms of POTS

The symptoms of POTS vary greatly, making it a difficult condition to diagnose. They can range from very mild to very severe, and include:

• Light-headedness, dizziness or fainting
• Heart palpitations
• Weakness or heaviness (especially of the legs)
• Shortness of breath
• Chest pain
• Blurred vision
• Headache
• Poor concentration (brain fog)
• Fatigue
• Gastrointestinal symptoms, such as nausea, cramps, bloating, constipation, or diarrhoea
• Sleep disorders
• Difficulty exercising
• Anxiety
• Coldness or pain in the extremities

The condition seems to predominantly affect two groups of patients, with a female to male ratio of 5:1. In adults, it affects mostly women aged 30-50, and in teenagers, it affects majority of girls, usually in the beginning of their puberty, within a year of their growth spurt.

The condition may develop following pregnancy, viral infection, surgery or trauma such as head injury.

Causes of POTS

The causes of POTS are unknown, however patients with POTS have been found to have one or more of the following: 

Autoimmunity. A recent study from Japan found autoimmunity markers in the blood of patients with POTS, suggesting that this is an autoimmune disease.

Genetic. Genes can play a role in some cases of POTS.

Low blood volume. Reduced amount of blood circulating in the body.

Joint hypermobility. Many patients of POTS suffer from joint hypermobility, a syndrome characterised by recurrent dislocation of joints.

Neuropathy. Impaired peripheral nerves, especially those in the legs and feet.

Chronic fatigue syndrome. Data suggests that 40% of patients with chronic fatigue syndrome also suffer from POTS.

Overactivity of the sympathetic nervous system. These patients have excessive levels of noradrenaline (norepinephrine) in the blood. This is the hormone secreted from the adrenal glands as part of ‘fight-or- flight’ response to stress, and amongst other things, it causes an increase in heart rate and blood pressure.

Mast Cell Activation Disorder. A mast cell is a type of blood cell that produces the chemical histamine in allergic reactions. Some patients with POTS experience flushing and increased urinary levels of histamine.

What should I do if I’m diagnosed with POTS?

Your doctor may suggest certain medications that can be very effective in reducing your symptoms. However, it takes more than medications to get better. There are many simple lifestyle changes that can greatly improve your symptoms and make a difference, including:

Avoid factors that can aggravate the condition, such as prolonged standing, dehydration, overheating, and consumption of alcohol.

Increase your fluids – some clinicians recommend drinking 2-3 litres per day, with at least one glass of water at meal time and at least two between meals. Increase salt in your diet by about 1 teaspoon a day (unless you suffer from high blood pressure).

Eat small and frequent meals, avoid large high-carbohydrate meals

Wear elastic support stockings – compression of the lower legs can increase blood return to the heart.

Sleep with the foot of the bed slightly elevated

Use sleep hygiene practices – good sleeping habits encourage a good night sleep. For example, going to bed at the same time each day, making your bedroom as peaceful as possible, avoiding coffee in the evening, etc.

Exercise – a regular exercise program that combines aerobic exercise and resistance training is vital. ​Activate your calf muscles to improve blood flow in the lower leg. 

Try Cognitive Behaviour Therapy T(CBT). Many patients find that it helped them come to terms with the condition and manage their daily life better.

Identify and avoid using medications that may exacerbate symptoms, such as medications known to lower blood pressure.

Find a support group, online or in person.

The bottom line

POTS is a relatively unknown and poorly understood condition that can affect almost every organ of the body, and can impact on every aspect of life; physically, socially and emotionally. For some patients, it may take months and even years to be diagnosed. The good news is that most patients, especially teenagers, do get better.

References

1. Anjum, I. et al., 2018. Postural Orthostatic Tachycardia Syndrome and Its Unusual Presenting Complaints in Women: A Literature Minireview. Cureus, 10(4), p.e2435. Available at: http://www.ncbi.nlm.nih.gov/pubmed/29876157  
2. Lau, D.H. et al., 2016. Towards Improved Care of Postural Tachycardia Syndrome, Inappropriate Sinus Tachycardia and Vasovagal Syncope Patients: A Call to Action in Australia. Heart, Lung and Circulation, 25(1), pp.8–11. Available at: http://linkinghub.elsevier.com/retrieve/pii/S1443950615014249  
3. Mizumaki Koichi, 2011. Postural Orthostatic Tachycardia Syndrome (POTS). J Arrhythmia, 27(4). Available at: https://www.sciencedirect.com/science/article/pii/S1880427611800311
4. National Center for Advancing Translational Sciences 2017. Postural orthostatic tachycardia syndrome. Available at: https://rarediseases.info.nih.gov/diseases/9597/postural-orthostatic-tachycardia-syndrome
5. Watari, M. et al., 2018. Autoimmune postural orthostatic tachycardia syndrome. Annals of Clinical and Translational Neurology, 5(4), pp.486–492. Available at: http://www.ncbi.nlm.nih.gov/pubmed/29687025  
6. Wells, R. et al., 2018. Postural tachycardia syndrome: current perspectives. Vascular health and risk management, 14, pp.1–11. Available at: http://www.ncbi.nlm.nih.gov/pubmed/29343965