Introduction

Postural orthostatic tachycardia syndrome (PoTS) is a disorder whereby changing positions, often from sitting or lying down to standing, is accompanied by a sustained increase in heart rate and, oftentimes, dizziness or light-headedness. Roughly a quarter of the total blood volume of the body is in the thorax while lying down. When the body raises itself, a portion of the blood and shifts downwards towards the lower body. In a healthy setting, the autonomic system would compensate for this large shift of volume through the sympathetic nervous system to suppress the parasympathetic system. The inability of the body to regulate the heart rate in response to the pressure changes when standing is an autonomic nervous system dysfunction. As a result, PoTS exerts a noticeable impact on quality of life, from minor inconvenience to being unable to perform daily activities the moment they get up.

The main purpose of this article is to inform about the long-term outlook of POTS and the variability in symptoms experienced by patients, to better enlighten patients about what to expect with the natural course of the disorder and how to manage it. Since POTS is usually present alongside other medical conditions, the precise cause of this autonomic dysfunction is difficult to pinpoint.¹ However, it is important to note that symptoms and treatments of POTS vary on a patient-to-patient basis. Therefore, everyone’s journey is different and requires resilience to find what works for each person for recovery and improvement.

Common signs of PoTS and who usually gets it

PoTS is estimated to affect 0.2% of the UK population; the typical demographic most affected consists of young women and adolescents.² Women of childbearing age, between 15 and 30, are five times more likely to be diagnosed with PoTS than men¹ 

Common symptoms include:

• A quickened heart rate within 10 minutes of standing
• Lightheadedness
• Palpitations
• Feeling as if about to faint (pre-syncope)

Other symptoms can include weakness (particularly in the legs), fatigue, fainting, nausea, tremulousness, sleep disturbances, headaches or migraines, shortness of breath, chest pain, bloating, diarrhoea, exercise intolerance, hyperventilation, anxiety, difficulty concentrating, chronic pelvic pain, blue discolouration in fingertips and feet.³ Although many symptoms commonly appear with PoTS, it may not always be the singular cause, but rather another disease in conjunction with PoTS results in the onset of other symptoms. As many diseases are commonly associated with PoTS, many of the respective diseases’ symptoms reported overlap and therefore interfere with the identification of PoTS.

Diseases associated with PoTS:

• Joint hypermobility (Ehlers-Danlos syndrome)
• Autoimmune diseases
• Hypovolemia
• Mast cell activation
• Post-viral infection (i.e. COVID-19)
• Myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS)
• Hypervigilance or anxiety
• Limited autonomic neuropathy

Diagnosis

PoTS is defined as an increase of 30 bpm (beats per minute) or more within 10 minutes of standing upright, though for adolescents aged 12 to 19, this threshold is 40 bpm; in the absence of orthostatic hypotension (low blood pressure), overt causes of sinus tachycardia, and with a record of chronic symptoms (over 6 months) of orthostatic intolerance.⁴ The average standing heart rate of those with PoTS is 120 bpm within 10 minutes of rising, and variation should be kept in mind, particularly for those with a low resting heart rate.³ To ascertain this diagnosis and fulfil the above criteria, a detailed medical history is crucial to avoid misdiagnosis and eliminate other potential causes such as hyperthyroidism, anaemia, postural hypotension, and phaeochromocytoma. Misdiagnosis is more common than expected due to multiple factors such as lack of awareness among medical professionals, readings taken only when seated that appear normal.

Interestingly, PoTS symptoms are typically reported after an evident medical event such as a viral infection, pregnancy, surgery, or trauma. Viable causes of sinus tachycardia are medication (nitro-glycerine, isoproterenol), medical conditions, dietary factors, and physiological stimuli, which need to be excluded through testing or examination of previous medical records. The most common tests for PoTS are the stand test, 12-lead electrocardiogram (ECG), and table tilt test, though additional laboratory tests may be requested.

Stand test

Heart rate and blood pressure are measured as the person is instructed to lie down in the supine position and then stand. Measurements are recorded in 2-minute intervals for up to 10 minutes as the patient remains standing. Those affected by PoTS may exhibit coldness and blue mottling in their extremities and foot swelling in prolonged standing. If the heart rate exceeds and is sustained at 30 bpm more than the resting heart rate within 10 minutes, then the patient may have PoTS.

Table tilt test

Another test is the table tilt test, a person is laid on a specialised bed and firmly secured. Electrodes and a blood pressure monitor are also attached to measure heart rate and blood pressure respectively. The bed is slowly tilted upwards to 60 degrees; depending on the professional it could be 70 degrees up to 90, at which the heart rate, blood pressure, and observable symptoms is monitored again for 10 minutes at 2-minute intervals.

12-Lead ECG

Despite not being a direct test for PoTS, it is often conducted alongside the former two tests to eliminate the possibility of cardiac conduction abnormalities or an accessory bypass tract being the cause.

Long-term outlook

Overall, PoTS is a chronic condition that is not life-threatening. Nearly 90% of PoTS sufferers generally improve with physical and pharmaceutical therapy, although there is no definitive cure; 60% of patients become fully functioning as before PoTS diagnosis.^5,6 Half of the people with PoTS whose PoTS symptoms were triggered by a viral infection recover in a 2 to 5 year period, becoming either symptomless or can perform daily activities with minimal restriction.⁶ However, a subgroup of PoTS with elevation of a type of signalling molecule named norepinephrine tends to suffer with more severe symptoms and typically require indefinite therapy.⁶ For PoTS which arises from other existing condition(s), the prognosis is dependent on the improvement of the initial condition(s). Importantly, the younger the patient, the better the prognosis, suggesting a more promising likelihood of PoTS management and recovery. The prognosis of PoTS is limited and requires more well-designed studies to fully understand the full course of the disease, many of which are in progress.

Symptom variability and fluctuation

A sustained increase in heart rate within 10 minutes of standing from lying or sitting down is the principal sign of PoTS, but this is almost never the only symptom reported and is more confounding when considering other medical conditions present. Each patient’s journey varies depending on their reported symptoms, medical history, symptom severity, lifestyle and sex. Treating PoTS also does not necessarily mean that the other co-existing conditions are treated. Even within a singular day, some patients note that symptoms are worse in the morning, whilst others say that the symptoms persist frequently throughout the day.⁵

Women with PoTS also give accounts of fluctuations in symptom severity according to their menstrual cycles, noting worsening symptoms during the pre-menstrual or early follicular phase, when oestrogen and progesterone levels are lowering.⁵

Physical therapy 

Progressively intensive physical exercise supervised by physical trainers or physiotherapists who understand the underlying causes of PoTS is recommended for all PoTS patients as a lifelong habit. Short-term graduated exercise, at least 3 months, led to improvement or remission of symptoms for the majority of PoTS sufferers.⁷ Unless the PoTS itself prevents exercise, in which case it must be addressed first, a large proportion of cases are unable to fully adhere to the program and hence cannot experience benefits and can have complaints of added fatigue, which should be anticipated when starting an exercise programme.⁵

The recommended exercise regimen would typically begin with exercises avoiding the upright position to not trigger symptoms, with swimming, recumbent biking, and rowing machines, for instance, with increasing duration and severity. Resistance training is introduced alongside these aerobic exercises once competent, which increases cardiac and skeletal muscle mass.⁵

Lifestyle changes doctors might recommend:

• Avoidance of large meals, alcohol, excessive heat, medicines that lower blood pressure, and prolonged standing
• Increased fluid intake to 3L a day, salt intake between 5-10g a day
• Compression garments (abdominal or waist-high tights)
• Sleeping with the head posts elevated by 4 to 6 inches
• Drugs for severe symptoms impeding physical therapy or daily life
• Cognitive behavioural therapy for chronic illness and hypervigilance or anxiety
• Postural manoeuvres to avoid fainting (i.e. squatting, leg crossing)
• In emergencies, IV fluid administration in the hospital

Most lifestyle changes intend to increase blood volume to lessen the effects of the sympathetic nervous systems, which affects the increase in heart rate. However, not all lifestyle changes listed are appropriate for everyone and recommendations from health professionals are made with individual consideration. Increasing hydration and salt intake might not be suitable for someone with cardiovascular or renal issues, for example.⁵ Drug treatment is not commonly recommended as there are no officially licensed medicinal treatments for PoTS, and it has potential side effects, and is seen more as a last resort, but depending on the type of symptoms, other medical conditions and how much PoTS is affecting life, it may be prescribed.⁷ Some drugs prescribed include: midodrine; fludrocortisone; pyridostigmine; propranolol; atenolol; phenobarbital; clonidine; SSRI's; droxidopa; ivabradine; histamine receptor blockers; amphetamines.²

Summary

PoTS is a life-changing syndrome affecting daily life to varying degrees and is different in everyone. Understanding the uniqueness of every individual helps those with PoTS to be more resilient in pursuing and finding out what therapies work for them, requiring much discipline and patience. As PoTS is not a widespread condition, finding and building a support community is important as well as knowing what help is available in the UK, such as STARS or PoTS UK.