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{{Postural orthostatic tachycardia syndrome}}
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'''''Synonyms and Keywords:''''' postural tachycardia syndrome, POTS
'''''Synonyms and Keywords:''''' postural tachycardia syndrome, POTS


==Overview==
==[[Postural orthostatic tachycardia syndrome overview|Overview]]==
'''Postural orthostatic tachycardia syndrome''' is a condition of [[dysautonomia]], and more specifically, [[orthostatic intolerance]], in which a change from the [[supine position]] to an upright position causes an abnormally large increase in heart rate, called [[tachycardia]].  This is often, but not always, accompanied by a fall in blood pressure. Patients with POTS have problems maintaining homeostasis when changing position, i.e. moving from one chair to another or reaching above their heads. Many patients also experience symptoms when stationary or even while lying down. Symptoms present in various degrees of severity depending on the patient. POTS is a serious, though non-life threatening, medical condition that can be severely disabling and debilitating. Many patients are unable to attend school or work, and especially severe cases can completely incapacitate the patient.
Postural orthostatic tachycardia syndrome is a poorly understood autonomic disturbance, which manifests as a change in Heart Rate>30BPM upon the patient standing erect from supine or a head-up tilt without underlying orthostatic hypotension. Sympathetic hyperstimulation secondary to a fall in vascular tone and cerebral hypoperfusion leads to transient symptoms such as inappropriate sinus tachycardia, chronic fatigue and dizziness. Many patients also report non specific symptoms such as GI disturbances and sleep disturbances. This incapacitating syndrome has no known etiology, with theories listing post infectious, autoimmune, cardiac deconditioning and emotional states as possible factors. Antinuclear antibodies along with elevated ganglionic, adrenergic, and muscarinic acetylcholine receptor antibodies have all been reported. Diagnosis involves eliminating all primary cardiac, endocrine, neuropathic and psychiatric causes of postural tachycardia. Treatment is multimodal and consists of patient education, volume replenishment, physical countermaneuvers (graded stockings) and pharmacological therapy.  


==Historical Perspective==
==[[Postural orthostatic tachycardia syndrome historical perspective|Historical Perspective]]==
POTS was first named and identified by Schondorf and Low in 1993, 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 and "idiopathic hypovolemia" by Fouad. Hypotension associated with POTS has been previously described as the "neurally mediated hypotension" form of POTS.
POTS was not identified as a separate entity until 1982, and until then was considered as part of a larger collection known as "irritable heart" syndrome or "Da Costa syndrome" named after Jacob Da Costa. Jacob Mendes Da Costa worked at Satterlee Hospital in Philadelphia. He studied over 400 patients with non-specific cardiac complaints during the American civil war. He recognized a pattern between the patients and named the collection of symptoms "irritable heart" in 1862. By 1871 he compiled and published his results. "irritable heart" encompassed many distinct conditions including POTS and psychiatric conditions which were later separately identified. The condition was described in 1993 by Ronald Schondorf and Phillip A. Low of the Mayo Clinic.
 
==[[Postural orthostatic tachycardia syndrome pathophysiology|Pathophysiology]]==
==Symptoms==
The pathophysiology is poorly understood and multifactorial. There are many reported findings across patients with POTS, which are interlinked and present in a variety of combinations, making it difficult to pinpoint one as primary and thereby causative. Evidence suggests that the etiology involves:
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 (medical)|vertigo]], which is also called dizziness)
*exercise intolerance
*extreme [[fatigue (physical)|fatigue]]
*[[Fainting|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 (psychology)|burnout]]
*decreased mental stamina
*[[depression (mood)|depression]]
*difficulty finding the right word
*impaired concentration
*[[sleep disorders]]
 
Inappropriate levels of [[epinephrine]] and [[norepinephrine]] lead to anxiety-like symptoms:
*[[chills]]
*feelings of fear
*[[Flushing (physiology)|flushing]]
*[[hyperthermia|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.
 
==Differentiating POTS from Other Disorders==
Most people with POTS don't feel well when they stand up, but they do not have [[syncope]] ([[pass out]]).  In contrast, patients with [[vasovagal syncope]] ([[VVS]]) also known as [[neurocardiogenic syncope]] ([[NCS]]) do have syncopal episodes, but feel fine in between episodes.
About 30% of patients with POTS also have  [[vasovagal syncope]] ([[VVS]]) also known as [[neurocardiogenic syncope]] ([[NCS]])
 
===Associated Conditions===
*POTS is often accompanied by [[vasovagal syncope]], also called "[[neurally mediated hypotension]]" ([[NMH]]) or "[[neurocardiogenic syncope]]" ([[NCS]]). [[Vasovagal syncope]] is a fainting reflex due to a profound drop in blood pressure. Autonomic disfunction that occurs with these disorders causes blood to inappropriately pool in the limbs away from the heart, lungs, and brain. The combination of misdirected bloodflow and hypotension will invoke syncope. Tachycardia associated with POTS may be a cardiac response to restore cerebral hypoperfusion.
*POTS may be a cause of [[chronic fatigue syndrome]] in patients that exhibit signs of [[orthostatic intolerance]]. Treating POTS will greatly improve or even eliminate disabling fatigue for these patients.
*Some patients with [[fibromyalgia]] complain of dysautonomia-related symptoms. Treating these patients for POTS will often improve myofascial and neuropathic pain.
*Autonomic dysfunction is most likely responsible for [[irritable bowel syndrome]] in many patients as well.
*Patients with [[Ehlers-Danlos Syndrome]] (EDS) often develop POTS as a secondary condition.
*Some POTS patients experience symptoms associated with [[Restless Leg Syndrome]], or RLS. Treating POTS should also relieve RLS symptoms in these patients.
Vasovagal syncope (VVS) - a blackout / faint caused by the vagal nerve being stimulated and causing a drop in blood pressure and or a slowing of the heart rate, it causes you to become unconscious briefly. Can also be called Neurocardiogenic syncope (NCS)
 
==Causes==
The causes of POTS are not fully known. Most patients 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]] or [[pneumonia]]. Some patients develop symptoms after experiencing some sort of trauma such as a car accident or injury. Women can also develop POTS during or after [[pregnancy]]. These patients generally have a poorer prognosis.  In one large test, 12.5% of 152 patients with POTS reported a family history of orthostatic intolerance, suggesting that there is a genetic inheritance associated with POTS. <ref>Thieben, MJ, Sandroni, P, Sletten, DM, et. al Postural orthostatic tachycardia syndrome: the Mayo clinic experience.  Mayo Clin Proc 2007; 82:308.</ref>


* Distal denervation with preservation of cardiac innervation. Studies have shown reduced response to stimulation in the lower limbs in patients with POTS. This is thought to be due to a neuropathy arising post infection, however there is also evidence of autoantibodies against the ganglionic acetylcholine receptor, lending support for an autoimmune origin of the disease.
* Hypovolemia or possible increased baroreceptor sensitivity. The most significant finding to lead to this theory is the symptomatic relief experienced by patients after infusion of saline, along with findings that suggest a predisposition to volume constriction in these patients. Conversely, constant and prolonged sympathetic activation could cause a mild reduction in circulating volume.
* abnormal venous function causing decreased preload on standing. Evidence of venous pooling and therefore reduced venous return has been reported in some studies, along with the reduction of symptoms with the use of compression trousers. This could be due to the denervation of the distal limbs or the increased release of vasodilators.
* cardiovasclar deconditioning
* hyperadrenergic state (increase in sympathetic activity)
*Post infectious etiology.
* genetic factors<br />
==[[Postural orthostatic tachycardia syndrome differential diagnosis|Differentiating POTS from Other Disorders]]==
<br />
==[[Postural orthostatic tachycardia syndrome epidemiology and demographics|Epidemiology and Demographics]]==
POTS is believed to be the most prevalent type of orthostatic intolerance. One study approximates the prevalence to be 500,000 americans. It is also commonly seen in younger patients (<45 years) who present to autonomic dysfunction clinics. Women are more likely to suffer from this disorder, with the ratio between genders being 4-5:1. The cause of this is unknown as yet. There is no racial predilection to this disorder.  <br />
==[[Postural orthostatic tachycardia syndrome risk factors|Risk Factors]]==
There are no clear risk factors for POTS, however a small minority of patients with the condition have been noted to have a mutated norepinephrine transporter gene. There is increasing evidence of association between POTS and joint hypermobility disorders such as Ehlers-Danlos syndrome. POTS may develop after a viral illness such as [[mononucleosis]], and is also reported to develop after illnesses requiring prolonged hospitalisation and immobility. Patients suffering from [[celiac disease]] and [[Sjögren's syndrome|Sjogrens syndrome]] may be at higher risk for developing POTS as well.
==[[Postural orthostatic tachycardia syndrome natural history, complications and prognosis|Natural History, Complications and Prognosis]]==
Most patients present young, and prognosis is generally favourable.
==Diagnosis==
==Diagnosis==
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]], [[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.


Between 75 and 80 percent of POTS patients are female and of the [[menstruating]] age. Most male patients develop POTS in their early to mid-teens during a [[growth spurt]] or following a viral or bacterial infection. Some women also develop POTS symptoms during or after [[pregnancy]].
[[Postural orthostatic tachycardia syndrome history and symptoms|History and Symptoms]] | [[Postural orthostatic tachycardia syndrome physical examination|Physical Examination]] | [[Postural orthostatic tachycardia syndrome laboratory findings|Laboratory Findings]] | [[Postural orthostatic tachycardia syndrome electrocardiogram|Electrocardiogram]] | [[Postural orthostatic tachycardia syndrome chest x ray|Chest X Ray]] | [[Postural orthostatic tachycardia syndrome echocardiography|Echocardiography]] | [[Postural orthostatic tachycardia syndrome other diagnostic studies|Other Diagnostic Studies]]
 
==Prognosis==
Most 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 by their mid twenties. Patients with post-viral POTS will also usually improve greatly or 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. Rarely, a teenager who develops POTS will gradually worsen overtime and have lifelong symptoms. Patients with secondary POTS as a consequence of [[Ehlers-Danlos Syndrome]] will also usually struggle with symptoms for life.
 
Recovered individuals do complain of occasional, non-debilitating recurrence of symptoms associated with autonomic dysfunction including dizzy spells, lightheadedness, flushing, transient syncope, and symptoms of irritable bowel syndrome.


<br />
==Treatment==
==Treatment==
There is at this time only one drug approved by the [[Food and Drug Administration|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===
[[Postural orthostatic tachycardia syndrome treatment guidelines|ACC/AHA/ESC Treatment Guidelines]] | [[Postural orthostatic tachycardia syndrome medical therapy|Medical Therapy]] | [[Postural orthostatic tachycardia syndrome cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Postural orthostatic tachycardia syndrome future or investigational therapies|Future or Investigational Therapies]]
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 inhibitor]]s (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 [[attention deficit disorder|ADD]] and [[attention deficit hyperactivity disorder|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.
==References==
{{Reflist|2}}
==Resources==
*[http://www.ndrf.org National Dysautonomia Research Foundation (NDRF)]
*[http://www.dynakids.org Dysautonomia Youth Network of America, Inc.]
*[http://www.potsplace.com/ Dysautonomia Information Network (aka POTS Place)]
*[http://home.att.net/~potsweb/POTS.html POTS, Patient's Report (aka POTSweb)]
{{Electrocardiography}}
{{Circulatory system pathology}}


[[Category:Cardiology]]
[[Category:Cardiology]]
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[[Category:Endocrinology]]
[[Category:Endocrinology]]
[[Category:Syndromes]]
[[Category:Syndromes]]
[[Category:Electrophysiology]]


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Latest revision as of 12:45, 14 June 2020

Postural orthostatic tachycardia syndrome Microchapters

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Synonyms and Keywords: postural tachycardia syndrome, POTS

Overview

Postural orthostatic tachycardia syndrome is a poorly understood autonomic disturbance, which manifests as a change in Heart Rate>30BPM upon the patient standing erect from supine or a head-up tilt without underlying orthostatic hypotension. Sympathetic hyperstimulation secondary to a fall in vascular tone and cerebral hypoperfusion leads to transient symptoms such as inappropriate sinus tachycardia, chronic fatigue and dizziness. Many patients also report non specific symptoms such as GI disturbances and sleep disturbances. This incapacitating syndrome has no known etiology, with theories listing post infectious, autoimmune, cardiac deconditioning and emotional states as possible factors. Antinuclear antibodies along with elevated ganglionic, adrenergic, and muscarinic acetylcholine receptor antibodies have all been reported. Diagnosis involves eliminating all primary cardiac, endocrine, neuropathic and psychiatric causes of postural tachycardia. Treatment is multimodal and consists of patient education, volume replenishment, physical countermaneuvers (graded stockings) and pharmacological therapy.

Historical Perspective

POTS was not identified as a separate entity until 1982, and until then was considered as part of a larger collection known as "irritable heart" syndrome or "Da Costa syndrome" named after Jacob Da Costa. Jacob Mendes Da Costa worked at Satterlee Hospital in Philadelphia. He studied over 400 patients with non-specific cardiac complaints during the American civil war. He recognized a pattern between the patients and named the collection of symptoms "irritable heart" in 1862. By 1871 he compiled and published his results. "irritable heart" encompassed many distinct conditions including POTS and psychiatric conditions which were later separately identified. The condition was described in 1993 by Ronald Schondorf and Phillip A. Low of the Mayo Clinic.

Pathophysiology

The pathophysiology is poorly understood and multifactorial. There are many reported findings across patients with POTS, which are interlinked and present in a variety of combinations, making it difficult to pinpoint one as primary and thereby causative. Evidence suggests that the etiology involves:

  • Distal denervation with preservation of cardiac innervation. Studies have shown reduced response to stimulation in the lower limbs in patients with POTS. This is thought to be due to a neuropathy arising post infection, however there is also evidence of autoantibodies against the ganglionic acetylcholine receptor, lending support for an autoimmune origin of the disease.
  • Hypovolemia or possible increased baroreceptor sensitivity. The most significant finding to lead to this theory is the symptomatic relief experienced by patients after infusion of saline, along with findings that suggest a predisposition to volume constriction in these patients. Conversely, constant and prolonged sympathetic activation could cause a mild reduction in circulating volume.
  • abnormal venous function causing decreased preload on standing. Evidence of venous pooling and therefore reduced venous return has been reported in some studies, along with the reduction of symptoms with the use of compression trousers. This could be due to the denervation of the distal limbs or the increased release of vasodilators.
  • cardiovasclar deconditioning
  • hyperadrenergic state (increase in sympathetic activity)
  • Post infectious etiology.
  • genetic factors

Differentiating POTS from Other Disorders


Epidemiology and Demographics

POTS is believed to be the most prevalent type of orthostatic intolerance. One study approximates the prevalence to be 500,000 americans. It is also commonly seen in younger patients (<45 years) who present to autonomic dysfunction clinics. Women are more likely to suffer from this disorder, with the ratio between genders being 4-5:1. The cause of this is unknown as yet. There is no racial predilection to this disorder.

Risk Factors

There are no clear risk factors for POTS, however a small minority of patients with the condition have been noted to have a mutated norepinephrine transporter gene. There is increasing evidence of association between POTS and joint hypermobility disorders such as Ehlers-Danlos syndrome. POTS may develop after a viral illness such as mononucleosis, and is also reported to develop after illnesses requiring prolonged hospitalisation and immobility. Patients suffering from celiac disease and Sjogrens syndrome may be at higher risk for developing POTS as well.

Natural History, Complications and Prognosis

Most patients present young, and prognosis is generally favourable.

Diagnosis

History and Symptoms | Physical Examination | Laboratory Findings | Electrocardiogram | Chest X Ray | Echocardiography | Other Diagnostic Studies


Treatment

ACC/AHA/ESC Treatment Guidelines | Medical Therapy | Cost-Effectiveness of Therapy | Future or Investigational Therapies


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