Postural orthostatic tachycardia syndrome

• 1. Introduction

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  Postural orthostatic tachycardia syndrome, usually shortened to POTS, was suspected as a factor when a British government minister fainted in Parliament on the 17th of June 2019. Nicola Blackwood was a junior minister who answered questions on health. Ministers customarily sit while a question is put to them, then rise to deliver the reply from the despatch box. In the space of twelve minutes she had stood up from her seat four times when she collapsed.

  Blackwood had told the public in March 2015 that she was diagnosed with Ehlers-Danlos syndrome in 2013 and had later been diagnosed with POTS. Afterwards she said: "I was frustrated and embarrassed my body gave up on me at work... But I am grateful it gives me a chance to shine a light on a condition many others are also living with."

  Her job demanded the very movement that this condition makes difficult. Why would the simple act of standing push a heart into overdrive? Why can it take years to put a name to the problem? And what can anyone actually do about it?

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• 2. The Thirty-Beat Test

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  Thirty beats per minute is the number that anchors a diagnosis. In adults, doctors look for a sustained rise of at least that much within ten minutes of moving from lying down to an upright position. The resulting pulse is typically above 120 beats per minute. For people aged 12 to 19, the bar is higher, at an increase of more than 40.

  Blood pressure supplies the second half of the verdict. A sustained drop of 20 mm Hg or more in the systolic reading would point to orthostatic hypotension instead, so POTS requires that no such drop occurs. The symptoms must also be frequent, worse when upright, better when lying down, and present for longer than three months.

  The classic instrument is the tilt-table test. The patient lies flat on a special table while heart rate and blood pressure are monitored, and the table is slowly tilted toward standing. Doctors see how the body reacts without the patient moving. Cheaper alternatives exist, including the NASA Lean Test and the adapted Autonomic Profile, which need less equipment. The Valsalva maneuver can also serve as an early hint of orthostatic intolerance because it may trigger fewer symptoms.

  A fast pulse on standing has many possible explanations, so much of the work is elimination. Spinal fluid leaks, dehydration, heart problems, adrenal insufficiency, epilepsy and Parkinson's disease must all be ruled out. Electrocardiography is normally performed on everyone to look for other causes of a racing heart. Echocardiography can check for mitral valve prolapse, and endocrine tests can exclude hyperthyroidism.

  One look-alike deserves special mention. Inappropriate sinus tachycardia presents similarly, but patients with it often have a resting heart rate above 100 beats per minute. People with POTS rarely exceed 100 while lying down, and their pulse shifts more sharply with posture.

  The path to an answer is long. Patients see an average of seven physicians first, and the average delay before diagnosis is 4.7 years. Cardiologists make the diagnosis in 41 percent of cases, neurologists in 19 percent and cardiac electrophysiologists in 15 percent.

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• 3. Fog and Fainting

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  In one survey of 138 POTS patients, 91 percent described their brain fog as forgetfulness. Difficulty thinking was reported by 89 percent, and trouble focusing by 88 percent. Eighty percent struggled to process what other people said, 71 percent felt confused, and 64 percent got lost. Another 40 percent said their thoughts moved too quickly.

  The same patients named their triggers. Fatigue led the list at 91 percent, followed by lack of sleep at 90 percent, prolonged standing at 87 percent and dehydration at 86 percent. Formal neuropsychological testing backs up the complaints. It has shown reduced attention, short-term memory, processing speed and executive function. One proposed explanation is lower blood flow to the brain while upright, possibly with a loss of the usual link between brain activity and blood supply.

  Fainting is the more visible symptom. Up to one-third of patients faint, whether from standing, exertion or heat. Some develop orthostatic headaches. Others see the legs or hands turn reddish-purple on standing as blood pools in the extremities.

  Fatigue is chronic in 48 percent of patients, and 32 percent report disturbed sleep. The list continues with excessive sweating or none at all, heat intolerance, bloating, constipation, diarrhea, post-exertional malaise and a neck and shoulder ache known as coat-hanger pain.

  In the most severe cases the pulse pressure falls to 0 mm Hg on standing, which leaves a person practically pulseless while upright. Many of those affected struggle to stand at all. Even in milder cases, people report that their quality of life suffers in standing, sport, school, work and religious activities.

  Still, not everyone fits this picture. Some patients show nothing beyond the fast heart rate itself.

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• 4. Competing Mechanisms

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  Low blood volume, called hypovolemia, appears in many people with POTS. With less blood to circulate, the heart beats faster to keep output up, a response known as reflex tachycardia. That compensation can bring on the near-fainting state called presyncope.

  Norepinephrine, a stress hormone and nerve signal, defines another group. In the 30 to 60 percent of cases classed as hyperadrenergic POTS, levels of it rise on standing, often because of low blood volume or partial nerve damage in the autonomic system. A smaller minority, labeled central hyperadrenergic, have standing levels that are typically very high even without either problem. These patients are more likely to report prominent palpitations and anxiety, and their blood pressure climbs markedly when they stand.

  The neuropathic type involves loss of sympathetic nerve supply in the lower limbs. The blood vessels there constrict poorly, so blood pools in the veins of the legs and the heart speeds up to compensate. Sweat tests show a loss of sweating in the feet in these patients, along with impaired norepinephrine release in the leg but not the arm.

  A subset of patients show reduced uptake of a tracer called MIBG in the heart on scintigraphy scans. This may signal nerve damage in the heart itself, although a shortage of the norepinephrine transporter could produce the same result.

  Then there is deconditioning. Prolonged bed rest and POTS both bring cardiac atrophy and reduced blood volume. In most cases, though, classic cardiovascular deconditioning and POTS remain distinct, and many patients show features of several types at once.

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• 5. After the Virus

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  In up to 50 percent of cases, symptoms begin after a viral illness. Physical trauma, concussion, pregnancy, surgery, menarche and psychosocial stress have also been linked to onset. One belief is that such events could set off an autoimmune response that results in POTS.

  The evidence for autoimmunity is growing. A high number of patients carry elevated autoantibodies against the α1-adrenergic receptor and the muscarinic acetylcholine M4 receptor. Higher levels of the first type go with more severe symptoms. Smaller groups of patients have shown other autoantibodies, and one cohort showed signs of innate immune activation with inflammatory cytokines. That has sparked interest in immunomodulation therapy, which would aim to calm the harmful antibody response.

  COVID-19 added a new route into the condition. A 2023 review found that the chance of a POTS diagnosis within 90 days of mRNA vaccination was 1.33 times higher than in the 90 days before. The result is inconclusive, because only 12 newly diagnosed cases were reported, and all 12 patients had autoimmune antibodies. By comparison, the risk of POTS-related diagnoses was 5.35 times higher after SARS-CoV-2 infection than after mRNA vaccination. About 30 percent of severely infected long COVID patients have POTS. Proposed mechanisms include hypovolemia, antibodies against autonomic nerve fibers and direct toxic effects of the virus.

  When another disease is the cause, the label is secondary POTS. Chronic diabetes, multiple sclerosis, lupus, Sjögren's disease, Marfan syndrome, Ehlers-Danlos syndrome and infections such as Epstein-Barr can all be responsible. POTS can occasionally be a paraneoplastic syndrome linked to cancer. A trio of POTS, Ehlers-Danlos syndrome and mast cell activation syndrome is becoming more common, with a genetic marker shared by all three. For patients in that trio, treating the mast cell condition can significantly improve POTS symptoms.

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• 6. Who Carries It

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  One in eight POTS patients in one study reported a family history of orthostatic intolerance, which suggests genetics plays a part. The average age of onset is 20, and the condition often begins in the teenage years.

  Women are far more likely to be affected. One estimate puts the female-to-male ratio at 4:1, and another source suggests that up to 94 percent of patients are female.

  Prevalence is hard to pin down. One study estimated a minimum of 170 cases per 100,000 people, and the true figure is probably higher because of underdiagnosis. Another study estimated at least 500,000 cases in the United States, while a broader estimate runs from one million to three million.

  POTS also travels with other conditions. Migraine appears in 40 percent of patients and irritable bowel syndrome in 30 percent. Ehlers-Danlos syndrome shows up in 18 to 25 percent, and asthma and fibromyalgia each in about 20 percent. Raynaud's syndrome, iron deficiency anemia and autoimmune disease each affect 16 percent, and gastroparesis 14 percent. Vasovagal syncope is reported in 13 to 25 percent, inappropriate sinus tachycardia in 11 percent and mast cell activation disorder in 9 percent. Evidence of POTS appears in 10 to 20 percent of people with myalgic encephalomyelitis/chronic fatigue syndrome, and dysautonomia may underlie both.

  The condition has also reached elite sport. Taiwanese tennis player Latisha Chan revealed in 2024 that she was diagnosed in 2014 and was receiving treatment ahead of the Summer Olympics. Her condition was considered career-threatening, yet external counterpulsation has extended her career by over a decade.

  Olympic gold medalist swimmer Katie Ledecky described a mild form of POTS in her 2024 memoir Just Add Water. Latvian basketball player Kristaps Porziņģis was sidelined for much of the 2024-25 NBA season with it.

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• 7. Treatment Without Approval

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  Eight to ten cups of water a day is the usual advice, especially after waking, to expand blood volume. No treatment has received approval from the U.S. Food and Drug Administration for POTS, and large clinical trials have not confirmed any strategy. Care therefore combines several methods at once.

  Salt helps the body hold on to water, whether added to food, taken in tablets or drunk in sports drinks. When oral fluids and salt are not enough, intravenous saline or the drug desmopressin can increase fluid retention. Small, frequent meals suit patients whose symptoms worsen after large ones. Alcohol and carbohydrate-heavy food can aggravate symptoms, and heavy caffeine intake may promote fluid loss by increasing urine production. Extreme heat can also make things worse.

  Prolonged inactivity can worsen symptoms, so graded exercise and endurance training help some patients. A common recommendation is 20 minutes of aerobic exercise, three times a week. When upright exercise worsens tachycardia, a recumbent bicycle, rowing or swimming keeps the body semi-reclined. Exercise programs should not be used for patients who also have ME/CFS. Outside exercise, a sustained hand grip can briefly raise blood pressure when standing up or finishing a meal, and compression garments squeeze the blood vessels from outside.

  If these measures fail, doctors turn to medication, all of it off-label as of 2013 and none tested in long-term randomized trials. Fludrocortisone boosts sodium retention and blood volume, though it may cause low potassium. Pyridostigmine restrains heart rate and eases chronic symptoms in about half of the patients reviewed, but gastrointestinal side effects limit its use in around 20 percent.

  Ivabradine slows the sinus node without altering blood pressure. In an open-label trial, about 60 percent of treated patients improved. Other options include phenylephrine, which suffers from poor oral bioavailability, ephedrine, pseudoephedrine, methylphenidate, bupropion and droxidopa. Midodrine, used for the neuropathic form, is taken only in daylight hours because it may promote supine hypertension.

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• 8. A Name Takes Shape

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  In 1871, physician Jacob Mendes Da Costa described a condition resembling POTS and called it irritable heart syndrome. Cardiologist Thomas Lewis later coined the term soldier's heart, because it often appeared among military personnel. The condition became known as Da Costa's syndrome, a label now understood to cover several distinct disorders, POTS among them.

  The modern name arrived in stages. Postural tachycardia syndrome was coined in 1982 to describe a patient whose heart raced on standing without any drop in blood pressure. In 1993, Ronald Schondorf and Phillip A. Low of the Mayo Clinic first used the full name, postural orthostatic tachycardia syndrome.

  Outcomes are better than the long road to diagnosis might suggest. About 80 percent of patients improve with treatment, and about 90 percent respond to a combination of drugs and physical methods. Sixty percent return to their original level of functioning. Yet 25 percent are so disabled they cannot work, and a few worsen over time.

  What triggered the condition matters. More than half of the patients whose POTS followed a viral infection get better within five years. One case series found that 94 percent of long COVID patients with POTS improved within 159 days of their first clinic visit. A systematic review reported improvement in 86 percent of post-COVID cases, though many stayed symptomatic for months.

  Age matters as well. People who develop POTS in their early to mid teens tend to respond well, while outcomes are more guarded for newly diagnosed adults. The hyperadrenergic type typically needs continuous therapy. Even among adolescent-onset patients, a retrospective study found that only 19 percent had full resolution of symptoms five years after diagnosis.

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