Postural orthostatic tachycardia syndrome ( POTS ) is a condition in which the change from lying to standing causes an enormous increase in heart rate. This occurs with symptoms that may include dizziness, difficulty thinking, blurry vision, or weakness. Other commonly related conditions include irritable bowel syndrome, insomnia, chronic headache, Ehlers-Danlos syndrome, fibromyalgia.
The cause of POT is poorly understood. It often starts after a viral infection, surgery, or pregnancy. Risk factors include family history of the condition. Diagnosis in adults is based on an increase in heart rate greater than 30 beats per minute within ten minutes of standing accompanied by symptoms. Low blood pressure by standing, however, does not occur. Other conditions that can cause the same symptoms, such as prolonged sleep, dehydration, hyperthyroidism, anemia, and certain medications, should not be present.
Treatment may include avoiding factors that carry symptoms, increasing salt and water food, compression stockings, exercise, cognitive behavioral therapy, and medications. Medications used may include beta blockers, pyridostigmine, midodrine, or fludrocortisone. More than 50% of people whose condition is triggered by viral infection get better within five years. Approximately 90% improved with treatment. An estimated 0.5 to 3 million people are affected in the United States. The mean age of onset is 20 years and it is more common in women.
Video Postural orthostatic tachycardia syndrome
Signs and symptoms
A typical POTS sign is an elevated heart rate measured at least 30 beats per minute in 10 minutes assuming an upright position. For people aged between 12 and 19 years, the minimum increase for diagnosis is 40 beats per minute. This symptom is known as orthostatic (erect) tachycardia (rapid heartbeat). This occurs in the absence of a drop in blood pressure, because it will show orthostatic hypotension. It should be noted, however, that certain drugs to treat POTS can cause orthostatic hypotension. This is accompanied by other features of orthostatic intolerance - symptoms that develop in an upright position and diminish by lying down. Orthostatic symptoms include palpitations, dizziness, chest discomfort, shortness of breath, nausea, weakness or "weight" in the lower leg, blurred vision and cognitive difficulties. Symptoms can be exacerbated by sitting longer, standing longer, alcohol, heat, exercise, or eating big meals.
In up to one-third of people with POTS, fainting occurs in response to postural or sport changes. Headaches such as migraines are common, sometimes with symptoms worsening in an upright position (orthostatic headache). Some people with POTS develop acrocyanosis, or acne, red/blue on the skin when standing, especially on the feet (indicating blood clots). 48% of people with POTS reported chronic fatigue and 32% reported sleep disturbances. Others only show cardinal symptoms of orthostatic tachycardia.
Maps Postural orthostatic tachycardia syndrome
Cause
POTS symptoms can be caused by several different pathophysiological mechanisms. This mechanism is poorly understood, and can overlap, with many showing the features of some POTS types. Many people with POTS show low blood volume (hypovolaemia), which can lower the rate of blood flow to the heart. To compensate for this, the heart increases its cardiac output by beating faster, leading to presyncope symptoms and reflex tachycardia.
In 30% to 60% of cases classified as hyperadrenergic POTS , norepinephrine levels rise in standing position, often due to hypovolemia or partial autonomic neuropathy. A small number of people with POTS have a high norepinephrine (usually very high) level that increases even in the absence of hypovolemia and autonomic neuropathy; this is classified as hyperadrenergic center POTS . High levels of norepinephrine contribute to the symptoms of tachycardia. Other subtypes, neuropathic POTS , are associated with the denervation of the sympathetic nerves in the lower limbs. In this subtype, it is thought that the disturbance of the narrowing of blood vessels causes blood to pool in the lower limbs of the lower limbs. Heart rate increases to compensate for this union of blood.
In up to 50% of cases, POTS is associated with recent viral illness. It can also be associated with physical decay or chronic fatigue syndrome. During viral diseases or resting in old beds, the body can become conditioned against orthostatic intolerance and central nervous system stimulation, resulting in failure to re-adapt to normal demands for standing or exercising.
POTS is more common in women than men. It has also been shown to be associated in patients with acute stressors such as pregnancy, recent surgery, or recent trauma. POTS is also associated with patients with a history of autoimmune disease, IBS, anemia, hyperthyroidism, fibromyalgia, diabetes, amyloidosis, sarcoidosis, systemic lupus erythematosus, and cancer. Genetics probably played a role, with one study finding that 1 in 8 POTS patients reported a history of orthostatic intolerance in their family.
Secondary
If POTS is caused by other conditions, this can be classified as secondary POTS . Chronic diabetes mellitus is one of the main causes that are often seen. POT can also be secondary to gastrointestinal disorders associated with low fluid intake due to nausea or fluid loss through diarrhea, leading to hypovolemia.
There are parts of patients who come with POTS and mast cell activation syndrome (MCAS), and it is unclear whether MCAS is a secondary cause of POTS or only comorbidities, but treating MCAS for these patients can significantly improve POTS symptoms.
POTS can also occur simultaneously in all types of Ehlers-Danlos syndrome (EDS), hereditary connective tissue disorder characterized by loose hipermobile joints susceptible to subluxation and dislocation, skin showing moderate or greater weakness, easy bruising, and many other symptoms. Trifecta POTS, EDS, and Mast Cell Activation Syndrome (MCAS) are becoming increasingly common, with common genetic markers among the three conditions. POTS is also often accompanied by vasovagal syncope, with 25% reported overlap. There is significant overlap between POTS and chronic fatigue syndrome, with POTS evidence in 25-50% of cases of CFS. Fatigue and reduced exercise tolerance are prominent symptoms of both conditions, and dysautonomia may underlie both conditions.
POTS can sometimes be a paraneoplastic syndrome associated with cancer. Autoantibodies have been found in some cases that occur after a viral infection increases the likelihood that some cases are autoimmune.
Diagnosis
Diagnostic criteria
The POTS diagnosis requires the following characteristics:
- For patients aged 20 or over, an increase in heart rate> = 30 bpm in 10 minutes of upright posture (slope or standing test) from supine position
- For patients aged 12-19 years, heart rate increase should be & gt; 40 bpm
- Associated with worse related symptoms with upright posture and improved with lying back
- Chronic symptoms that last> 6 months
- In the absence of any other disorders, drugs, or functional states known to cause a predisposition of orthostatic tachycardia
Orthostatic intolerance
The increase in heart rate after moving to an upright posture is known as orthostatic (erect) tachycardia (rapid heartbeat). This occurs in the absence of a drop in blood pressure, because it will show orthostatic hypotension. It should be noted, however, that certain drugs to treat POTS can cause orthostatic hypotension. This is accompanied by other features of orthostatic intolerance - symptoms that develop in an upright position and diminish by lying down. Orthostatic symptoms include palpitations, dizziness, chest discomfort, shortness of breath, nausea, weakness or "weight" in the lower leg, blurred vision and cognitive difficulties.
Differential diagnosis
Various autonomic tests are used to rule out autonomic disorders that may underlie symptoms, while endocrine testing is used to rule out hyperthyroidism and more rare endocrine conditions. Electrocardiography is usually performed on all patients to rule out other possible causes of tachycardia. In cases where certain related conditions or complication factors are suspected, other non-autonomous tests may be used: echocardiography to rule out mitral valve prolapse, and thermal threshold tests for small fiber neuropathy.
Testing the cardiovascular response to prolonged head tilt, exercise, eating, and heat stress can help determine the best strategy for managing symptoms. POTS has also been divided into several types (see Ã,§ Causes), which may benefit from different treatments. People with a neuropathic POT show a sweating loss in the leg during a sweat test, as well as a disorder of norepinephrine release in the legs, but not arms. It is believed to reflect the peripheral sympathetic denervation of the lower limbs. People with hyperadrenergic POT show increased blood pressure and norepinephrine levels when standing, and are more likely to suffer from prominent palpitations, anxiety, and tachycardia.
Treatment
POTS treatment involves using several methods in combination to combat cardiovascular dysfunction, overcoming symptoms, and simultaneously addressing related disorders. For most patients, water intake should be increased, especially after awakening, to increase blood volume (reduce hypovolaemia). 8-10 glasses of water daily is recommended. Increasing salt intake, by adding salt to food, taking salt tablets, or drinking sports drinks and other electrolyte solutions is an effective way to increase blood pressure by helping the body retain water. Different physicians recommend different amounts of sodium to their patients. Salt intake is not appropriate for people with high blood pressure. Combining these techniques with physical training gradually improves the effect. In some cases, when increased oral fluid and insufficient salt intake, intravenous saline or desmopresin medication are used to help improve fluid retention.
Great food worsens symptoms for some people. These people may benefit from eating frequent small meals throughout the day instead. Alcohol and foods high in carbohydrates may also aggravate the symptoms of orthostatic hypotension. Excessive consumption of caffeine drinks should be avoided, as they may increase urine production (causing fluid loss) and consequently hypovolaemia. Extreme heat exposure can also aggravate symptoms.
Prolonged physical activity may worsen the symptoms of POTS. Techniques that increase a person's capacity for exercise, such as endurance training or multilevel training, can ease symptoms for some patients. Aerobic exercise for 20 minutes a day, three times a week, is sometimes recommended for patients who can tolerate it. Exercise may have a direct effect of worsening tachycardia, especially after eating or on a hot day. In this case, it may be easier to exercise in a semi-recumbent position, such as riding a bicycle, rowing, or swimming.
When changing to an upright posture, completing a meal or exercise concluding, sustained handrails can raise blood pressure briefly, possibly relieving symptoms. Compression garments can also be useful by limiting blood pressure with external body pressure.
Drugs
If nonpharmacological methods are not effective, treatment may be necessary. By 2013, there are no drugs approved by the US Food and Drug Administration to treat POTS, but various off-label uses. Their efficacy has not been checked in long-term randomized controlled trials.
Fludrocortisone can be used to improve sodium retention and blood volume that may be beneficial not only by enlarging sympathetic-mediated vasoconstriction but also because most POTS patients appear to have a low absolute blood volume.
While POTS patients usually have normal or even elevated arterial blood pressure, the neuropathic form of POTS is thought to be a selective sympathetic denervation of the veins. In these patients, Midodrine's selective alpha-1 adrenergic receptor agonist may increase venous return, increase stroke volume and improve symptoms. Midodrine should only be taken during the day because it can increase supine hypertension.
Ivabradine can successfully withstand heartbeat in POTS without affecting blood pressure and about 60% of POTS patients treated in open-label ivabradine trials have improved symptoms.
Pyridostigmine has been reported to restrain heart rate and improve chronic symptoms in about half of patients.
Selective phenylephrine alpha 1 selective agonists have been used to improve venous return and stroke volume in some people with POTS. However, these drugs may be inhibited by poor oral bioavailability.
Prognosis
POTS has a favorable prognosis when managed appropriately. Symptoms improve within five years of diagnosis for many patients, and 60% return to their original function level. Approximately 90% of people with POTS respond to a combination of pharmacological and physical treatments. Those who develop POT in their early to mid-adolescent during a period of rapid growth are likely to see complete symptom completion within two to five years. More results are maintained for newly diagnosed adults with POTS. Some people do not recover, and some even get worse over time. This type of hyperadrenergic POTS usually requires ongoing therapy. If POTS is caused by other conditions, the results depend on the underlying disruption prognosis.
Epidemiology
POTS prevalence is unknown. One study estimates a rate of at least 170 POTS per 100,000 individuals, but the actual prevalence is likely to be higher because of underdiagnosis. Another study estimates that there are between 500,000 and 3,000,000 cases in the United States. POT is more common in women, with a male-to-female ratio of 5: 1. Most people with POTS are between the ages of 20 and 40, with an average onset of 30 years. The diagnosis of POT beyond the age of 40 is rare, probably because symptoms improve with age.
History
In 1871, physician Jacob Mendes Da Costa described a condition that resembled the modern concept of POTS. He named it irritable heart syndrome . Cardiologist Thomas Lewis expanded his description, incorporating the term "heart of warrior" because it was often found among military personnel. This condition came to be known as Da Costa syndrome, which is now recognized as several different disorders, including POTS.
Postural tachycardia syndrome was created in 1982 in the description of patients with postural tachycardia, but not orthostatic hypotension. Ronald Schondorf and Phillip A. Low from the Mayo Clinic first used the name postural orthostatic tachycardia syndrome in 1993.
References
External links
Source of the article : Wikipedia
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