Postural orthostatic tachycardia syndrome
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]
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Synonyms and Keywords: postural tachycardia syndrome, POTS
Overview
Historical Perspective
Pathophysiology
Differentiating POTS from Other Disorders
Risk Factors
Natural History, Complications, Prognosis
Diagnosis
Symptoms
The hallmark symptom of POTS is an increase in heart rate from the supine to upright position of more than 30 beats per minute or to a heart rate greater than 120 beats per minute within 10 minutes of head-up tilt. This tachycardic response is often accompanied by a profound decrease in blood pressure and a wide variety of symptoms associated with hypotension including:
- Lightheadedness, sometimes called pre-syncope (pre-fainting) dizziness (but not vertigo which involves a spinning sensation, or dizziness)
- Exercise intolerance
- Extreme fatigue
- syncope (fainting)
Chronic or acute hypoperfusion of tissues and organs in the upper parts of the body are thought to cause the following symptoms:
- Cold extremities
- Chest pain and discomfort
- Disorientation
- Dyspnea
- Headache
- Muscle weakness
- Tremulousness
- Visual disturbances
Autonomic dysfunction is thought to cause additional gastrointestinal symptoms:
- Abdominal pain or discomfort
- Bloating
- Constipation
- Diarrhea
- Nausea
- Vomiting
Cerebral hypoperfusion can cause cognitive and emotive difficulties:
- Brain fog
- burnout
- Decreased mental stamina
- Depression
- Word finding difficulty
- Impaired concentration
- Sleep disorders
Inappropriate levels of epinephrine and norepinephrine lead to anxiety-like symptoms:
- Chills
- Feelings of fear
- Flushing
- Overheating
- Nervousness
- Over-stimulation
Symptoms of POTS overlap considerably with those of generalized anxiety disorder, and a misdiagnosis of an anxiety disorder is not uncommon.
Laboratory Studies
Tests to rule out Addison's Disease, pheochromocytoma, electrolyte imbalance, Lyme Disease, Celiac Disease, Ehlers-Danlos Syndrome, and various food allergies are usually performed. A blood test may be performed to verify abnormally high levels of norepinephrine present in some POTS patients.
Tilt Table Testing
A tilt table test is vital to diagnosing POTS, although all symptoms must be considered before a final diagnosis is made.
Treatment
There is at this time only one drug approved by the FDA to treat orthostatic intolerance, however several classes of drugs often provide symptom control and relief. Treatments must be carefully tested due to medication sensitivity often associated with POTS patients, and each patient will respond to different therapies in different ways. Most patients will respond to some form of treatment.
Fludrocortisone
The first line of treatment for POTS is usually fludrocortisone, or Florinef, a corticosteroid used to increase sodium retention and thus increase blood volume and blood pressure. An increase in sodium and water intake must coincide with fludrocortisone therapy for effective treatment. Dietary increases in sodium and sodium supplements are often used. Gatorade is also effective in providing both sodium and fluid.
Beta Blockers
Beta blockers such as atenolol and propanolol are often prescribed to treat POTS. These medications work by blocking the effects of epinephrine and norepinephrine released by the autonomic nervous system. Beta blockers also reduce sympathetic activity by blocking sympathetic impulses.
Midodrine
Midodrine (Proamatine), is approved by the U.S. FDA to treat orthostatic hypotension, a condition related to POTS. It is a stimulant that causes vasoconstriction and thereby increases blood pressure and allows more blood to return to the upper parts of the body. Use of midodrine is often discontinued due to intolerable side-effects, and it is known to cause supine hypertension (high blood pressure when lying down).
Antidepressants
Antidepressants, especially selective serotonin reuptake inhibitors (SSRIs) such as Prozac, Zoloft, Celexa, Lexapro, and Paxil, can be extremely effective in re-regulating the autonomic nervous system and raising blood pressure. Some studies indicate that serotonin-norepinephrine reuptake inhibitors (SNRIs) such as Effexor and Cymbalta are even more effective. Tricyclic antidepressants, tetracyclic antidepressants, and monoamine oxidase inhibitors are also occasionally, but rarely, prescribed. A combination of two antidepressants, usually an SSRI or SNRI with Wellbutrin or Remeron, is also shown to be very effective.
Stimulants
Medications used to treat ADD and ADHD such as Ritalin and Adderall are used to balance dopamine levels, increase vasoconstriction, and increase blood pressure.
Anxiolytics
Anti-anxiety medications, such as Xanax, Ativan, and Klonopin, can be used to combat imbalances of adrenaline usually seen with POTS patients.
Other Medications
- Angiotensin converting enzyme inhibitors, or ACE inhibitors, are used to increase vasoconstriction, cardiac output, and sodium and water retention.
- Clonidine can work in patients with reduced sympathetic activity. Ironically an anti-hypertensive drug, Clonidine promotes production and release of epinephrine and norepinephrine.
- Disopyramide, or Norpace, is an antiarrhythmic medication that inhibits the release of epinephrine and norepinephrine.
- Erythropoietin, used to treat anemia via intravenous infusion, is very effective at increasing blood volume. It is seldom used, however, due to the dangers of increasing the hematocrit, the inconvenience of intravenous infusion, and its prohibitively expensive cost.
- Pregabalin, or Lyrica, an anticonvulsant drug, has been shown to be especially effective in treating neuropathic pain associated with POTS. In fact, Lyrica is currently the only prescription drug approved by the FDA to treat fibromyalgia. Some POTS patients also report improvement in concentration and energy while on Lyrica.
- Pseudoephedrine and phenylephrine, over the counter decongestants, increase vasoconstriction by promoting the release of norepinephrine.
- Pyridostigmine, or Mestinon, inhibits the breakdown of acetylcholine, promoting autonomic nervous system activity. It is especially effective in patients who exhibit symptoms of excessive sympathetic activity.
- Theophylline, a drug used to treat respiratory diseases such as COPD and asthma, is occasionally prescribed at low doses for POTS patients. Theophylline increases cardiac output, increases blood pressure, and stimulates epinephrine and norepinephrine production. Due to its very narrow therapeutic index, Theophylline is known to cause a wide variety of side-effects and even toxicity.
- Women who report a worsening of symptoms during menstruation will often use combined (containing both estrogen and progestin) forms of hormonal contraception to prevent hormonal changes and an aggravation of their condition.
Dietary Changes
- Alcohol has been shown to drastically exacerbate all types of orthostatic intolerance due to its vasodilation and dehydration properties. It should be avoided whenever possible because of its adverse effects and its interactivity with many of the medications prescribed to POTS patients.
- Caffeine helps some POTS patients due to its stimulative effects, however, other patients report a worsening of symptoms with caffeine intake. Each patient should experiment to determine whether caffeine helps or hurts his or her condition.
- Diets high in carbohydrates have been connected to impaired vasoconstrictive action. Eating foods with lower carbohydrate levels can mildly improve POTS symptoms.
- Eating frequent, small meals can reduce gastrointestinal symptoms associated with POTS by requiring the diversion of less blood to the abdomen.
- Patients diagnosed with POTS will usually be advised to maintain a high sodium diet in order to augment the effects of their medication regimen, especially if that regimen includes fludrocortisone. Patients should also drink plenty of fluids, with a recommended intake of at least two liters per day and as much as 500 milliliters every two hours throughout the day.
Physical Therapy
POTS symptoms can be worsened by postural asymmetries, restrictions in mobility, and areas of adverse mechanical tension in the nervous system. These physical abnormalities can be relieved with gentle manual therapies including neural mobilization (or neural tension work), myofascial release, and cranio-sacral therapy.
External Body Pressure
Pressure garments can reduce symptoms associated with orthostatic intolerance by constricting blood pressures with external body pressure. Compression hose and anti-embolism stockings, both knee and thigh-high, provide relief for many patients. For especially severe cases, military anti-shock trousers and anti-gravity suits, or g-suits can be helpful but also limiting.
Exercise
Exercise is very important for maintaining muscle strength and avoiding deconditioning. Though many POTS patients report difficulty exercising, some form of exercise is essential to controlling symptoms and eventually, improving the condition.