Postural orthostatic tachycardia syndrome

Postural orthostatic tachycardia syndrome (POTS, or postural tachycardia syndrome) is a condition in which a change from the supine position (lying horizontally) to an upright position causes an abnormally large increase in heart rate, called tachycardia. It is a form of orthostatic intolerance (OI), a type of dysautonomia, which means a dysregulation of the autonomic nervous system (ANS). The autonomic nervous system controls those functions of the body that are considered automatic and involuntary, such as heart rate, blood pressure, respiration, digestion, and arousal. Other symptoms of an orthostatic nature — occurring in response to upright posture — typically accompany the tachycardia. These include, but are not limited to headaches, fatigue, sweating, nausea; fainting and dizziness. The female to male ratio of patients with POTS is 4:1.

Onset
Onset may be linked to infection including viruses like EBV or enteroviruses, trauma, surgery or stress.

Signs and symptoms
The main symptom of POTS is an abnormal increase in heart rate upon standing. The specific diagnostic criteria for POTS is an increase in heart rate from the lying to upright position of greater than 30 beats per minute, or a heart rate of greater than 120 beats per minute within 10 minutes of standing. There needs to be an absence of significant orthostatic hypotension (magnitude of blood pressure drop ≥ 20/10 mm Hg) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8920526/. Patients with POTS usually present with other symptoms, commonly occurring in the upright position. These include: Common stimuli in daily life, such as modest exertion, food ingestion and heat, can exacerbate symptoms.
 * Hypovolemia (low blood volume)
 * High levels of plasma norepinephrine when standing
 * Dizziness/lightheadedness and syncope (fainting)
 * Headaches and migraines
 * Cognitive impairment / brain fog
 * Heart palpitations
 * Chest pain
 * Shortness of breath
 * Sleep abnormalities
 * Neuropathic pain, Coldness or pain in the extremities
 * Small fiber polyneuropathy (in 50% of patients)
 * Fatigue
 * Exercise intolerance
 * Nausea
 * Tremulousness (shaking)
 * Acrocyanosis-- reddish purple discoloration in the legs, due to poor circulation in the extremities, which returns to normal upon returning to a reclined position
 * Sensory sensitivity
 * Abdominal pain, gastroparesis, or rapid gastric emptying
 * Elevated sympathetic tone

Potential mechanisms
Autoimmunity is thought to play a role in many cases of POTS: adrenergic, muscarinic and other autoantibodies  have been found. A small study of POTS in children found that 24.39% of patients had acetylcholine receptor autoantibodies. A small study of adult patients found elevated α1, β1 and β2 adrenergic receptor autoantibodies.

Lax vasculature has been though to play a role in the development of POTS in people with Ehlers-Danlos Syndrome, a connective tissue disorder.

Testing
https://www.youtube.com/watch?v=5H5FZTAic7c Assessing orthostatic blood pressure can be done in a physician's office by measuring the patient's blood pressure while lying down, sitting, and standing at standardized time increments. Dr. Lucinda Bateman uses a modified orthostatic blood pressure assessment called the NASA 10-minute Lean Test, a variant of a test used by NASA researchers to test for orthostatic intolerance following space flight. The NASA 10-minute Lean Test is less taxing on the patient and can be done in any physician's office. Instructions are available for printout for both healthcare providers and patients.

If the results of the standard orthostatic blood pressure assessment are inconclusive, a tilt table test can be used for diagnosis.

Treatment
A 2012 study Diagnosis and management of postural orthostatic tachycardia syndrome: A brief review concluded:


 * "The pathophysiology of POTS is complex and the result of a number of separate mechanisms producing a common pattern of symptoms. The large number of clinical manifestations that characterize this disorder and the wide range of medications available, plus the clear evidence that certain medications and treatment strategies work in some, but not all POTS patients, demonstrates that POTS is a range of disorders requiring comprehensive investigation and characterisation to guide selection of the most appropriate treatment. The recent consensus statement will help to direct further research into the underlying conditions that lead to POTS."
 * When the cause of POTS is able to be identified and treated in certain individuals, their POTS symptoms may subside. However, there is currently no cure for POTS on the broader level. The following treatments have been identified to improve symptoms and quality of life:
 * Increasing fluid intake (2-3 liters a day)
 * Increasing salt intake
 * Raising the head of the bed to conserve blood volume (less blood is turned into urine by the kidneys when reclining at an angle)
 * Diet
 * Reclined exercise, such as rowing, biking, swimming (contraindicated in patients with co-morbid myalgic encephalomyelitis)
 * Sodium chloride 0.9% (Normal saline)
 * Medications:
 * Beta-blockers
 * Fludrocortisone
 * Ivabradine
 * Erythropoietin
 * Pyridostigmine bromide (Mestinon)
 * Vasoconstrictors
 * NSAIDs
 * Others such as methyldopa and antidepressants

A small randomized crossover design trial found that patients with postural orthostatic tachychardia improved with Mestinon.

Conditions associated with POTS
POTS is not only comorbid with a range of diseases, but its phenotype also resembles that of other disorders (e.g., ME, Ehlers-Danlos Syndrome).

ME/CFS
POTS can be a co-morbid condition in ME/CFS patients. Estimates on the prevalence of POTS among ME/CFS patients varies widely, from 11% to 70%. In a 2008 study done in the UK by the Northern CFS/ME Clinical Network, using the Fukuda criteria, 27% of the study population had POTS compared with 9% in the control population.

A 2011 study of 58 POTS patients by the Vanderbilt Autonomic Dysfunction Center (Vanderbilt University School of Medicine, Nashville, TN, U.S.A.), reported that 64% of also met the Centers for Disease Control and Prevention (CDC) criteria for chronic fatigue syndrome.

The SEID criteria requires either orthostatic intolerance (of which POTS is one type) or cognitive dysfunction for a diagnosis. POTS is also a symptom of the Canadian Consensus Criteria (CCC) which diagnoses ME/CFS, and the International Consensus Criteria (ICC) for diagnosing myalgic encephalomyelitis (ME). However, the diagnosis of POTS alone does not automatically support a ME/CFS diagnosis and cannot be used as a diagnostic biomarker to determine ME/CFS. POTS can occur independent from ME/CFS, and, likewise, ME/CFS can occur without the symptomatology of POTS.

A 2016 study in the Netherlands by Roerink et al., found that patients with CFS who fulfilled the SEID criteria did not have a prevalence of POTS different from that in the overall ME/CFS population. In adults with ME/CFS, the prevalence of POTS was low, between 6% - 18% (depending on age), was not different from the rate in non-ME/CFS fatigued patients, and was not related to disease severity or treatment outcome.

ME patients with POTS can experience impaired neurocognitive abilities (such as working memory, information processing) under increased orthostatic stress (i.e., standing, tilt table test).

Other conditions associated with POTS

 * Ehlers Danlos syndrome


 * Fibromyalgia


 * Autoimmune diseases


 * Chiari malformation


 * Infections such as mononucleosis, Epstein-Barr virus, Lyme disease, extra-pulmonary Mycoplasma pneumonia, and Hepatitis C


 * Mitochondrial diseases


 * Mast cell activation disorders


 * Vasovagal syncope

Notable research

 * 2008, Postural orthostatic tachycardia syndrome is an under-recognized condition in chronic fatigue syndrome (Full Text)
 * 2012, Diagnosis and management of postural orthostatic tachycardia syndrome: A brief review (Full Text)
 * 2012, Increasing orthostatic stress impairs neurocognitive abilities in chronic fatigue syndrome with postural tachycardia syndrome (Full Text)
 * 2013, What is brain fog? An evaluation of the symptom in postural tachycardia syndrome (Full Text)
 * 2014, Postural Orthostatic Tachycardia With Chronic Fatigue After HPV Vaccination as Part of the “Autoimmune/Auto-inflammatory Syndrome Induced by Adjuvants” (Full Text)
 * 2014, Comorbidity of postural orthostatic tachycardia syndrome and chronic fatigue syndrome in an Australian cohort (Full Text)
 * 2015, An assessment of fatigue in patients with postural orthostatic tachycardia syndrome (reprinted in 2017) (Abstract)
 * 2016, Is Postural Orthostatic Tachycardia a Useful Diagnostic Marker in Chronic Fatigue Syndrome Patients? (Abstract)
 * 2016, Postural orthostatic tachycardia is not a useful diagnostic marker for chronic fatigue syndrome (Abstract)
 * 2018, Managing fatigue in postural tachycardia syndrome (PoTS): The Newcastle approach (Abstract)
 * 2018, Postural Orthostatic Tachycardia Syndrome: Prevalence, Pathophysiology, and Management (Abstract)
 * 2019, Postural Orthostatic Tachycardia Syndrome Is Associated With Elevated G‐Protein Coupled Receptor Autoantibodies (Full text)

Learn more

 * POTS UK website
 * Sep 2010, Mangaging Orthostatic Intolerance
 * 2016, Recognizing postural orthostatic tachycardia syndrome
 * 2016, The Exercise Intolerance in POTS, ME/CFS and Fibromyalgia Explained?
 * 2019, Study may unlock new diagnostic tools for fainting disorder - possible biomarker for POTS and autoimmune evidence - University of Toledo