Postural orthostatic tachycardia syndrome

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Autonomic dysfunction
Classification and external resources
ICD-9337.9
MeSHD054972
 
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Autonomic dysfunction
Classification and external resources
ICD-9337.9
MeSHD054972

Postural orthostatic tachycardia syndrome (POTS, also postural tachycardia syndrome) is a condition of dysautonomia,[1] to be more specific orthostatic intolerance, in which a change from the supine position to an upright position causes an abnormally large increase in heart rate, called tachycardia. Several studies show a decrease in cerebral blood flow with systolic and diastolic cerebral blood flow (CBF) velocity decreased 44% and 60%, respectively.[2] People with POTS have problems maintaining homeostasis when changing position, e.g. moving from one chair to another or reaching above their heads. Many also experience symptoms when stationary or even while lying down.

Symptoms present in various degrees of severity depending on the individual. POTS can be severely debilitating. Some afflicted individuals are unable to attend school or work and for especially severe cases, they are completely incapacitated. This calls for reasonable 'adjustments' to be made by schools in line with Disability Educational Standards,[where?] to include the students in activities in which he or she has challenges in participating. An example of an adjustment may include distance learning and other helpful arrangements.[3]

Symptoms[edit]

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.[4]

This tachycardic response is sometimes accompanied by a decrease in blood flow to the brain and a wide variety of symptoms associated with cerebral hypoperfusion. Decreased cerebral perfusion may promote the following:[5]

Chronic or acute hypoperfusion of tissues and organs in the upper parts of the body are thought to cause the following symptoms:

Autonomic dysfunction is thought to cause additional gastrointestinal symptoms:

Cerebral hypoperfusion, when present, can cause cognitive and emotive difficulties. Symptoms that persist in the supine (recumbent) state are difficult to attribute to "cerebral hypoperfusion":

Inappropriate levels of epinephrine and norepinephrine lead to anxiety-like symptoms:

Symptoms of POTS overlap considerably with those of generalized anxiety disorder, and a misdiagnosis of an anxiety disorder is not uncommon. Some patients may be able to show a marked, and speedy, reddening of hands on lowering to resting position to challenge this misdiagnosis.

Associated conditions[edit]

Causes[edit]

The primary causal mechanisms in POTS remain unclear and are likely heterogeneous. Some people develop symptoms in their teenage years during a period of rapid growth and see gradual improvement into their mid-twenties. Others develop POTS after a viral or bacterial infection such as mononucleosis, pneumonia, or Lyme disease while others develop symptoms after experiencing some sort of trauma such as a car accident or injury.[10] Women can also develop POTS during or after pregnancy.

In one large test, 12.5% of 152 people with POTS reported a family history of orthostatic intolerance, suggesting that there is a genetic inheritance associated with POTS.[11]

While the primary causal mechanisms remain unclear, a number of theories have been offered based on preliminary research findings:

Diagnosis[edit]

POTS can be difficult to diagnose. A routine physical examination and standard blood tests will not indicate POTS. A tilt table test is vital to diagnosing POTS, although all symptoms must be considered before a final diagnosis is made. Tests to rule out Addison's Disease, pheochromocytoma, electrolyte imbalance, Lyme Disease, Celiac Disease, and various food allergies are usually performed.[citation needed] A blood test may be performed to verify abnormally high levels of norepinephrine present in some POTS patients.

Between 75 and 80 percent of POTS patients are female and of the menstruating age. Some women also develop POTS symptoms during or after pregnancy.

Prognosis[edit]

Many POTS patients will see symptom improvement over the course of several years. Those who develop POTS in their early to mid teens during a period of rapid growth will most likely see complete symptom resolution in two to five years.[38] Patients with post-viral POTS will sometimes improve greatly or even see a full symptom resolution. Adults who develop POTS, especially women during or after pregnancy, usually see milder improvement and can be plagued with their condition for life[citation needed]. Rarely, a teenager who develops POTS will gradually worsen over time and have lifelong symptoms. Patients with secondary POTS as a consequence of Ehlers-Danlos Syndrome will also usually struggle with symptoms for life. In some patients the only cure for POTS is time.[39]

Many adult patients report a relapsing/remitting course characterised by periods of partial remission and occasional 'flare-ups' or exacerbations.

Recovered individuals do complain of occasional, non-debilitating recurrence of symptoms associated with autonomic dysfunction including dizzy spells, lightheadedness, flushing, and transient syncope, as well as symptoms of irritable bowel syndrome[citation needed]. These symptoms are consistent with B12 deficiency in absence of anemia, which should always be ruled out directly by checking B12, homocysteine and methylmalonic acid.[40]

Treatment[edit]

Most patients will respond to some form of treatment. Lifestyle changes, in particular drinking extra water and avoiding trigger situations such as standing still or getting hot are necessary for all patients. Some patients also benefit from the addition of other treatments, such as certain medications.

Dietary changes[edit]

Physical therapy and exercise[edit]

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.[42] Exercises that improve leg and abdominal strength may aid in improving the muscle pump and, therefore, preventing pooling of blood in the abdomen and lower extremities.

Aerobic exercise performed for 20 minutes a day, three times a week, is sometimes recommended for patients who can tolerate it.[41] Certain modalities of exercise may be more tolerable initially, such as riding a recumbent bicycle or swimming. However, as tolerable, upright exercise may benefit the participant through orthostatic training. All exercise programs for POTS patients should begin with low-intensity exercises for a short duration and progress slowly.

Medications[edit]

Several classes of drugs often provide symptom control and relief for POTS patients. 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.[citation needed]

The first drug of choice for symptomatic relief of POTS is usually fludrocortisone, or Florinef, a mineralcorticoid 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.[citation needed]

Dietary increases in sodium and sodium supplements are often used.[citation needed]

An 80 mg capsule of Propranolol.

Beta blockers such as atenolol, metoprolol and propanolol are often prescribed to treat POTS. These medications slow down the excessive heart rate response (tachycardia) that POTS patients experience. They also work by blocking the effects of epinephrine and norepinephrine released by the Autonomic Nervous System. In addition, beta blockers reduce Sympathetic Nervous System activity by blocking Sympathetic impulses. For some patients, Beta blockers increase POTS symptoms (e.g., lowering blood pressure, increasing fatigue, which is why they are often prescribed in conjunction with Midodrine). Beta blockers may be dangerous to individuals with asthma or allergies.[citation needed]

Midodrine (Proamatine), is approved by the U.S. Food and Drug Administration (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). Some doctors prefer to start patients on Midodrine without the concomitant use of Beta blockers and then add Beta blockers once the dose of Midodrine has been properly adjusted. This gives the Midodrine time to start raising the patient's blood pressure which often helps avoid the hypotension that is a common side effect of Beta blockers. Obviously lowering the blood pressure of a POTS patient would exacerbate any existing orthostatic hypotension or worsen orthostatic intolerance.[citation needed]

Antidepressants, especially selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine (Prozac), sertraline (Zoloft), citalopram (Celexa), escitalopram (Lexapro), and paroxetine (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 venlafaxine (Effexor) and duloxetine (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 bupropion (Wellbutrin) or mirtazapine (Remeron), is also shown to be very effective.[citation needed]

Medications used to treat attention deficit disorder and attention deficit hyperactivity disorder such as methylphenidate (Ritalin) and Adderall effectively increase norepinehprine and dopamine levels, thereby increasing vasoconstriction and blood pressure.

In some cases, when increasing oral fluids and salt intake is not enough, intravenous saline is used to help increase blood volume, as many POTS patients suffer from hypovolemia.[17][43] Increasing blood volume can decrease POTS symptoms caused or worsened by low blood volume such as tachycardia, low blood pressure, fatigue, and syncope. Infusions can be taken on an as-needed basis in an Emergency Room, or on a regularly scheduled manner at an infusion center or at home with the assistance of a home-care nurse. Many patients report a profound though short-lived improvement in their symptoms from saline infusions.

In the UK, Ivabradine has been used to treat patients with POTS symptoms with good effect.[44][45] Ivabradine acts by reducing the heart rate in a mechanism different from that of beta blockers and calcium channel blockers, two commonly prescribed antianginal drugs. It is classified as a cardiotonic agent.

Trials are planned for other novel potential therapies for POTS.[47]

Patients whose POTS symptoms are due to B12 deficiency need pharmacological doses of B12 for repletion of tissues.[40]

Recently it has become a popular belief that medical marijuana may have positive effects on POTS patients. However, there is little evidence supporting its efficacy, and the active constituents of marijuana are often associated with postural hypotension.

There are anecdotal reports of benefit being derived from Horse Chestnut seed extract (Aescin), Rehmannia glutinosa, Licorice root, Eucommia ulmoides, Diosmin and Ruscus aculeatus (Butcher Broom)[48] however there is currently no research to support the efficacy of these herbal remedies that is specific to POTS.

External body pressure[edit]

Pressure garments can reduce symptoms associated with orthostatic intolerance by constricting blood pressures with external body pressure.

Compression devices, such as abdominal binders and compression stockings, help to reduce the amount of pooling blood. Compression stockings should be at least 30–40 mm Hg and will work best if they are waist-high.[49] Compression stockings should be fitted to achieve the greatest benefit. If the patient finds compression stockings of 30-40 mmHg to be too uncomfortable, consider a lesser compression such as 20-30 mmHg. Many patients see improvement with that level of compression, with full-length/waist-high stockings.

Compressions suits (G-Suits) have also been used with some good results.[50][51]

Changes in environment[edit]

Some patients report that symptoms worsen with changes in barometric pressure (for instance, before a thunderstorm) and changes from outdoors to indoors (it is presumed that barometric pressure is higher inside) and depending on weight of clothes and coverage. These patients may find relief by moving to a new location where barometric pressure is relatively stable, e.g. San Diego.[52][53][54]

History[edit]

POTS was first named and identified by Schondorf and Low in 1993;[55] however, the syndrome has been described in medical studies dating back to at least 1940. Hypertension associated with POTS has been previously described as the "hyperadrenergic syndrome" by Streeten[citation needed] and as "idiopathic hypovolemia" by Fouad.[56] Hypotension associated with POTS has been previously described as the "neurally mediated hypotension" form of POTS.

References[edit]

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External links[edit]