Postural Orthostatic Tachycardia Causes and Risk Factors

Postural Orthostatic Tachycardia Syndrome (POTS) is a form of dysautonomia that is estimated to impact between 1,000,000 and 3,000,000 Americans, and millions more around the world. POTS is a form of orthostatic intolerance that is associated with the presence of excessive tachycardia and many other symptoms upon standing.

Diagnostic Criteria

The current diagnostic criteria for POTS is a heart rate increase of 30 beats per minute (bpm) or more, or over 120 bpm, within the first 10 minutes of standing, in the absence of orthostatic hypotension.

In children and adolescents, a revised standard of a 40 bpm or more increase has recently been adopted.4,5 POTS is often diagnosed by a Tilt Table Test, but if such testing is not available, POTS can be diagnosed with bedside measurements of heart rate and blood pressure taken in the supine (laying down) and standing up position at 2, 5 and 10 minute intervals.

Doctors may perform more detailed tests to evaluate the autonomic nervous system in POTS patients, such as Quantitative Sudomotor Axon Reflex Test (QSART, sometimes called Q-Sweat), Thermoregulatory Sweat Test (TST), skin biopsies looking at the small fiber nerves, gastric motility studies and more.

Signs and Symptoms

While the diagnostic criteria focus on the abnormal heart rate increase upon standing, POTS usually presents with symptoms much more complex than a simple increase in heart rate.

It is fairly common for POTS patients to have a drop in blood pressure upon standing, but some POTS patients have no change or even an increase in blood pressure upon standing.1 POTS patients often have hypovolemia (low blood volume) and high levels of plasma norepinephrine while standing, reflecting increased sympathetic nervous system activation.3

Approxiamtely 50% of POTS patients have a small fiber neuropathy that impacts their sudomotor nerves.

Many POTS patients also experience fatigue, headaches, lightheadedness, heart palpitations, exercise intolerance, nausea, diminished concentration, tremulousness (shaking), syncope (fainting), coldness or pain in the extremeties, chest pain and shortness of breath.1,3,4

Patients can develop a reddish purple color in the legs upon standing, believed to be caused by blood pooling or poor circulation. The color change subsides upon returning to a reclined position.

How is PoTS diagnosed?

GPs may recognise the condition, but a clear diagnosis would normally be made by an electrophysiologist (a heart rhythm expert), neurologist or other hospital physician.

These specialists are often found in cardiology, blackout or syncope clinics (although only a minority of people with PoTS experience blackouts).

The following tests may be used to confirm a diagnosis or exclude other conditions with similar symptoms:

Active stand test. The patient rests flat for a few minutes and heart rate and BP are recorded. After standing up, further recordings are taken over 10 minutes.

Tilt table test. The patient rests flat on a special bed with a footplate whilst BP and heart rate recordings are made.

The bed is then tilted (head end up) for up to 45 minutes while further recordings are taken. (Both tests are stopped if the patient faints or if satisfactory recordings have been made).

Other tests may include 12-lead electrocardiogram (ECG), 24-hour ECG, 24-hour blood pressure monitoring, blood tests (full blood count, kidney and liver function, thyroid function, calcium, diabetes tests, lying and standing norepinephrine levels), echocardiogram, exercise test, autonomic screening tests.

Misdiagnosis

PoTS was first described in medical journals in 1993, but many medical professionals are still unaware of the condition today.

Patients are commonly misdiagnosed with other conditions such as anxiety and depression, reflex syncope (vasovagal syncope) and chronic fatigue syndrome.

If you think you could have PoTS, it may help to discuss this leaflet with your doctor and ask for a referral to a specialist with an interest in PoTS. There is a list of such doctors on the PoTS UK and STARS websites (see below).

What causes PoTS?

There are a number of factors and disorders causing or associated with the condition but in some cases a cause is never identified. PoTS can follow a viral illness such as glandular fever, or be linked to pregnancy or a traumatic event.

Sometimes teenagers are affected after a rapid growth spurt and most will improve within a few years. Some patients develop PoTS-like symptoms due to lack of fitness and the heart pumping inefficiently after being confined to bed for some time.

Hyperdrenergic PoTS may have a genetic cause. When upright, patients tend to complain of a severe sensation of anxiety and tremor, migraine headaches and clammy hands and feet.

They may also present with high blood pressure and high blood norepinephrine levels (also elevated in phaeochromocytoma, which needs to be excluded).

Conditions associated with PoTS

Joint hypermobility syndrome (JHS) is thought by some experts to be the same as Ehlers-Danlos hypermobility type (previously called Ehlers-Danlos type III and benign joint hypermobility syndrome) and is one of the most common conditions associated with PoTS.

Low blood pressure can be healthy, but if it drops very low on standing it is called orthostatic hypotension and can cause symptoms similar to PoTS.

Reflex syncope occurs when a drop in blood pressure results in fainting. PoTS, low blood pressure and reflex syncope can exist together in the same patient as seen in JHS and chronic fatigue syndrome.

Chronic fatigue syndrome (CFS). PoTS is estimated to affect around one third of people with CFS.

Inappropriate sinus tachycardia (IST) has similar symptoms to hyperadrenergic PoTS, but the high heart rate may be higher when lying down compared to PoTS and rapidly accelerates with exertion or stress.

Mast cell activation disorder needs to be considered if flushing or allergies are prominent.

Autoimmune conditions that have been associated with PoTS include Sjögren’s syndrome and antiphospholipid (Hughes’) syndrome. Treatment of underlying conditions can improve symptoms of PoTS.

Other conditions associated with PoTS include multiple sclerosis, diabetes, alcoholism, pure autonomic failure, multiple system atrophy (MSA), Lyme disease and cancer.

What can I do to improve my condition?

Lifestyle changes may be all that are needed to control symptoms.

Fluids

At least 2-3 litres of fluid per day are usually advised to boost blood volume. As symptoms can be worse in the morning, it may help to boost fluids before getting out of bed.

In an emergency, drinking 2 glasses of water quickly can rapidly elevate BP and lower heart rate.

Intravenous fluids have been used, but can cause serious complications with regular use.

Alcohol dilates blood vessels and may make symptoms worse.

Coffee and other caffeinated drinks may also worsen symptoms, although some find them helpful.

Food and salt

A high salt diet of up to 10 g per day may be recommended. Extra salt can be dangerous in some conditions such as high blood pressure, and kidney and heart disease, and therefore should only be taken if recommended by your doctor.

Salt tablets can also be prescribed. Slow Sodium® tablets are available in the UK on prescription and are coated to reduce nausea.

Eating small amounts and often can be helpful. Symptoms can worsen after a large meal as blood is diverted to the digestive tract and away from other areas.

Some people may find refined carbohydrates aggravate symptoms. Avoid rich sugary foods and those containing white flour. Eat lots of unprocessed foods such as vegetables, fruit, beans and foods that contain whole grain.

Posture

To avoid fainting or near fainting, take notice of early warning signs such as light-headedness, dizziness, and nausea. Lie down immediately and, if possible, elevate your legs. If your circumstances make this difficult cross your legs while standing or rock up and down on your toes. Clench your fists, buttocks and abdominal muscles.

The risk of fainting can also be minimised by standing up slowly if you have been sitting for a while. Avoiding prolonged standing or sitting. Elevating legs can be helpful.*

Compression tights

Compression tights should be waist high and give at least 30 mm Hg of pressure at the ankle (grade II compression) in order to help reduce the amount of blood pooling in the legs. Sports compression clothing may help.

Temperature regulation

Heat worsens symptoms. Dress in layers of clothes, so layers can be removed to prevent overheating. Extra salt and fluid intake should be increased if you feel hot or sweat more.

A spray bottle of water for your face and neck will cool you down as the water evaporates from your skin. A fan or air conditioning can be helpful. Cooling vests have been used.*

Fitness

Light to moderate exercise can help or even cure PoTS in some cases. Increasing leg strength and core (central) muscles helps to pump blood back to the heart.

Physical exertion can initially worsen PoTS so factor in recovery time afterwards. Begin with recumbent (sitting or lying down) exercise if you are starting for the first time, gradually increasing time and intensity. Upright exercise can be added after 2-3 months of recumbent exercise.

Twenty to thirty minutes of aerobic exercise should be undertaken at least three times a week in combination with resistance training.

Exercise recommended in PoTS

  • Swimming
  • Rowing
  • Recumbent biking, progressing on to upright biking
  • Pilates – mostly horizontal exercise focusing on core strength
  • Lower limb resistance training
  • Walking
  • Jogging
  • Sleep
  • Elevating the head of the bed is recommended to boost blood volume. PoTS patients often have poor quality sleep.

Potential causes of sleep disturbance need to be identified such as underlying anxiety and depression.

Pacing

Symptoms tend to be worse in the morning so it may be best to plan activities for later in the day. Set yourself achievable goals and avoid rushing. Factor in time for rest.

Hygiene

Drink a glass of fluid before and after showering. Avoid taking a hot or long shower or bath as this dilates your blood vessels and can make symptoms worse.

Finishing your shower with cool water may help. Sit on a stool by the basin and in the shower. Dry shampoo spray and wet wipes may be an option on a bad day!

Psychological support

Cognitive behavioural therapy (CBT) is a structured talking therapy that can help you work towards accepting your limitations, adjust to the unpredictability of chronic illness, and help you pace yourself to achieve the challenges of daily living whilst still maintaining activities which most help you feel positive and fulfilled.

Driving

Driving – by law you must tell the DVLA of any health condition that may affect your ability to drive. Failure to do so could lead to prosecution and invalidate your insurance.

Problems that you should consider reporting include tachycardia, syncope and dizziness.

Education and work

Eat and drink regularly. Working or studying with your feet elevated may help avoid brain fog. Don’t sit too long in one position. Move around or fidget.

Keep as fit as you can – consider swimming or Pilates.

If you cannot meet deadlines, tell your teachers or employer as soon as possible. Keep everyone informed. Providing a copy of this leaflet may be helpful.

POTS Classifications

POTS researchers have classified POTS in various ways. Dr. Blair Grubb has described POTS as “primary” or “secondary.”

“Primary” refers to POTS with no other identifiable medical condition (also known as “idiopathic” POTS).

“Secondary” refers to POTS with the presence of another medical condition known to cause or contribute towards POTS symptoms. Dr. Julian Stewart has described “high flow” and “low flow” POTS, based upon the flow of blood in the patients lower limbs.

Other researchers have described POTS based on some of its more prominent characteristics: hypovolemic POTS, which is associated with low blood volume; partial dysautonomic or neuropathic POTS which is associated with a partial autonomic neuropathy; and hyperandrenergic POTS which is associated with elevated levels of norepinephrine.

These are not distinct medical conditions and many POTS patients have two or three of the different characteristics present.

For example, one patient can have neuropathy, low blood volume and elevated norepineprhine.

Who Develops POTS?

POTS can strike any age, gender or race, but it is most often seen in women of child bearing age (between the ages of 15 and 50). Men and boys can develop it as well, but approximately 80% of patients are female.

Is POTS Caused by Anxiety?

While some of the physical symptoms of POTS overlap with the symptoms of anxiety, such as tachycardia and palpitations, POTS is not caused by anxiety.

POTS patients are often misdiagnosed as having anxiety or panic disorder, but their symptoms are real and can severely limit a person’s ability to function.

Research has shown that POTS patients are similarly or even less likely to suffer from anxiety or panic disorder than the general public. Research surveys that evaluate mental health show similar results between POTS patients and national norms.

What Causes POTS?

POTS is a heterogeneous (meaning it has many causes) group of disorders with similar clinical manifestations.1,4 POTS itself is not a disease; it is simply a cluster of symptoms that are frequently seen together. This is why the ‘S’ in POTS stands for “Syndrome.”

Since POTS is not a disease, it is fair to say that POTS is caused by something else. However, figuring out what is causing the symptoms of POTS in each patient can be very difficult, and in many cases, patients and their doctors will not be able to determine the precise underlying cause.

When doctors cannot pinpoint the underlying cause of a patient’s POTS, it may be called Primary or Idiopathic POTS.1 Idiopathic simply means “of an unknown origin.”

Prognosis

Currently, there is no cure for POTS, however researchers believe that some patients will see an improvement in symptoms over time.

Detailed long term follow up studies on the course of POTS are sparse, but Dysautonomia International is working with researchers to begin to collect long term follow up data.

With proper lifestyle adjustments, exercise, diet and medical treatments, many patients see an improvement in their quality of life. If an underlying cause can be identified, and if that cause is treatable, the POTS symptoms may subside.

While the prognosis is good for most patients, researchers have noted that some patients will not improve and may actually worsen over time.1

The longest follow-up study done to date comes from Mayo Clinic.20 Mayo Clinic did a survey of their pediatric POTS patients seen between 2003 and 2010.

Of those who responded to the survey, 18.2% reported a complete resolution of their POTS symptoms, while 52.8% reported persistent but improved symptoms.

Male patients were twice as likely to report recovery. The average survey respondent had been diagnosed for about 5 years.

Both patients who fully recovered and those who did not had mental health scores similar to the national norm.

Source & More Info: dysautonomiainternational.org and patient.co.uk

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