Introduction

What is postural orthostatic tachycardia syndrome?

Postural orthostatic tachycardia syndrome (PoTS), is a disorder of the autonomic nervous system, a part of the body responsible for controlling functions that we don’t influence or think about, such as blood pressure, digestion, and bladder control. PoTS is associated with symptoms including rapid heart rate changes, dizziness, fatigue, bloating and constipation, and problems with the bladder. It is more common in people assigned female at birth (AFAB), and usually occurs between the ages of 15 and 50. 

Orthostatic intolerance

Orthostatic intolerance is the hallmark symptom of PoTS. It refers to the symptoms caused by the condition and experienced when a person is in an upright posture, such as dizziness due to a drop in blood pressure, and a rapid increase in heart rate.¹ Symptoms are relieved by lying down.

The diagram below explains one of the main causes of orthostatic intolerance in PoTS. For more information on the symptoms and causes of PoTS, please read here. 

Importance of diagnosis and treatment

Diagnosis of PoTS can help to rule out other conditions and assist in customising your treatment. You can find out more about diagnosis here. Left untreated, PoTS could lead to complications such as reduced muscle mass as a result of prolonged periods of rest, head injury from repeated fainting episodes, and debilitating fatigue. Therefore, an effective treatment plan is essential to allow you to control your symptoms and improve your quality of life. 

Treatment of PoTS

Non-pharmacological methods

Patient education to avoid triggers

The PoTS UK website details advice for avoiding factors that may worsen your symptoms. 

You should aim to:

• Avoid excessively long periods of rest and physical deconditioning
• Avoid prolonged standing
• Avoid hot climates and areas of high humidity
• Rise from lying to a sitting or standing position gradually
• Try physical counter-manoeuvres, such as leg crossing and muscle tensing, when in an upright posture²

Dietary changes

Smaller meals

Eating smaller, more frequent meals has been shown to reduce postprandial hypotension – a decrease in blood pressure following a meal. This is because the amount of blood directed to the digestive tract is less for smaller meals.³

Gluten-free diet

A study indicated that a gluten-free diet may help to alleviate PoTS symptoms, particularly those involving the gastrointestinal tract, such as nausea, bloating, and abdominal pain.⁴

Increased salt and fluid intake

There is some evidence that drinking 3 litres of fluids per day and increasing dietary salt intake can be a useful treatment for PoTS because doing so promotes the retention of sodium in the body which causes your blood volume to expand. This, in turn, increases your blood pressure, causing you to feel less dizzy when becoming upright.^3,5

Compression stockings

Compression stockings may provide some benefit in the treatment of PoTS. Clinical guidance states that compression of the abdomen and legs tends to be more effective than compressing the legs alone. They work by preventing the pooling of blood at the feet, thus avoiding the need for your heart to beat excessively quickly when you stand up in order to maintain blood supply to the brain. Class 2 compression stockings are recommended for optimal benefit.^2,5

Exercise training

An exercise programme is a recommended component of a PoTS treatment plan. It should consist of non-upright aerobic exercise, such as swimming or rowing, with some resistance training for the thighs too. Upright exercise of increasing intensity can then be gradually incorporated provided it does not cause an exacerbation of your symptoms.⁶

A study in 2010 found that non-upright, aerobic exercise improved or even cured symptoms in patients with PoTS.⁷

Cognitive behavioural therapy (CBT)

This is a talking therapy in which you evaluate your thoughts and actions, and consider how they can be changed to help you manage a certain health problem. You may feel like you have to sacrifice activities that you previously enjoyed but now lead to a worsening of your symptoms, for example running.

Rather than thinking “I’m never going to be able to enjoy running again”, CBT encourages you to identify techniques, such as exercise training, that help you to engage in some degree of your pre-PoTS level of activity whilst also ensuring your symptoms are well managed.

Reviewing current medications

Under the guidance of a physician, medications that worsen orthostatic intolerance or tachycardia may be stopped. Those which may cause PoTS-like side effects may also be withdrawn also.⁶

Pharmacological methods

If your symptoms fail to respond to non-pharmacological methods or are particularly severe, your doctor may suggest various medications instead. 

As with any drug treatment, there are certain monitoring requirements that you may need. Some medications cause unwanted side effects, or may simply be ineffective. If this is the case, the drug can be discontinued and another trialled, until you find a single drug or combination of drugs that control your symptoms well. 

Blood volume expanders

These drugs work by increasing salt and water retention, causing your blood volume, and thus blood pressure to rise so that you feel less dizzy when upright. They include:

• Fludrocortisone
• Desmopressin
• Erythropoietin^3,5

Heart rate inhibitors

These drugs exert effects on certain channels in the heart with the overall aim to reduce heart rate. They include:

• Propranolol, atenolol, bisoprolol, and metoprolol – collectively known as ‘beta-blockers’
• Ivabradine – a ‘funny’ channel blocker
• Verapamil – a calcium channel blocker
• Pyridostigmine^2,8

Vasoconstrictors

Vasoconstrictors, as the name suggests, work by constricting blood vessels. They prevent blood from pooling at the feet, raising your blood pressure to avoid sensations of dizziness or light-headedness when assuming an upright posture. They include:

• Midodrine
• Octreotide
• Ergotamine
• Ephedrine and pseudoephedrine
• Methylphenidate^2,3,6

Sympatholytic agents

When the sympathetic nervous system is activated, the ‘fight-or-flight’ response is triggered; this is a reaction characterised by an increase in heart rate and blood pressure. It is thought that this response is chronically activated in PoTS so sympatholytic agents work by opposing these effects of sympathetic nervous system activation.

Examples of drugs used include:

• Clonidine
• Methyldopa⁵

Drugs for other associated symptoms or comorbidities 

Modafinil

Modafinil is a stimulant which can increase alertness and improve the brain fog that is associated with PoTS and a common comorbidity called chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME).⁶ 

Non-steroidal anti-inflammatory drugs (NSAIDs)

NSAIDs include ibuprofen or indomethacin which not only oppose the decreased blood pressure caused by a molecule known as prostaglandin, but also primarily act as pain relievers, and could be beneficial if you also suffer from fibromyalgia or headaches as a result of your PoTS.³

Antidepressants

Useful for mental health problems, such as depression and anxiety, some antidepressants, including amitriptyline and imipramine, also have pain-relieving properties which can be an added benefit to some patients.³

Antihistamines

Mast cell activation syndrome (MCAS) can affect some patients with PoTS and occurs when mast cells abnormally release histamines to cause symptoms including rash, fatigue, and changes in heart rate and blood pressure.

MCAS is treated with:

• H₁ antihistamines - cetirizine, fexofenadine, loratadine
• H₂ antihistamines - cimetidine, famotidine, ranitidine
• Sodium cromoglicate
• Ketotifen
• Montelukast

Challenges for treatment

There is no single specific drug for the treatment of PoTS. A lack of robust evidence is a pressing issue in the treatment of PoTS so greater research into this area is essential to ensure that you, as a patient, can receive the most appropriate care and thus have as normal a quality of life as possible. Unfortunately, research funding into PoTS treatment is limited, but with greater awareness of the condition, it is hoped that more evidence-based treatment methods will become integrated into medical practice.  

Summary

PoTS is a disorder of the autonomic nervous system, and primarily causes orthostatic intolerance and rapid heart rate on moving into an upright posture. Non-pharmacological treatments, such as avoiding triggers, increasing salt and fluid intake, and exercise training are generally exhausted before trialling medications, including fludrocortisone, ivabradine, and midodrine.

These work by increasing your blood pressure and slowing your heart rate. Evidence for the efficacy of PoTS drugs is scarce so greater funding for clinical trials is needed to better establish treatment options.