What is Postural Orthostatic Tachycardia Syndrome?

Based on this, POTS is a series of symptoms that happen together that relate to the position of the body, standing upright, and having a fast heartbeat. While that's the basis of it, there's a lot more to it that involves both the nervous system and the vascular system.

Humans have two parts of the nervous system: the somatic nervous system and the autonomic nervous system. Things that happen in the human body that are voluntary actions or responses, like kicking a ball, picking up the phone, or balancing food on a utensil and moving it to the mouth, are controlled by the somatic nervous system. The autonomic nervous system controls things that happen in the human body without us having to think about them--things that are automatic.(2) These are things like breathing, heart rate, sweating, hunger signals, and more.

Normally, the autonomic nervous system keeps a person's heart rate and blood pressure in balance. Whenever a person stands, lies down, bends over, or stands on their head, the heart makes sure the blood flows through the vessels evenly, even when gravity is working against them. Specifically, when a person stands, 10-15% of their blood settles in the abdomen, arms, and legs.(9) They may feel a bit light-headed as less blood reaches the brain for a few seconds, but moving the leg muscles helps the blood flow back to the heart. Additionally, the autonomic nervous system releases epinephrine and norepinephrine, hormones that cause the heart to beat a little faster and with a little more force to help get blood returning to the brain. Norepinephrine also helps constrict blood vessels so the blood can move through them against the force of gravity. If the autonomic nervous didn't do this, all of a person's blood would fall to their feet and stay there when they stood up.

In a person with POTS, the body can't coordinate the heart rate and blood vessel constriction to keep the blood moving through the body when the person stands up. Because more blood is pooling in the blood vessels below their heart (a larger amount than the average person (9)), the brain gives instructions to release more epinephrine and norepinephrine. The blood vessels don't respond to the hormones, but the heart does, causing it to beat faster and faster. Because less blood is getting to the brain, a person with POTS can feel light-headed and faint.

Due to those hormones that are released, a POTS patient’s heartbeat will beat faster than normal when moving from lying down to sitting or lying down to standing up. Usually this is an increase of "at least 30 beats per minute (bpm) in adults, or at least 40 beats per minute in adolescents, measured during the first 10 minutes of standing," according to Johns Hopkins Medicine.(6) POTS can also cause a heart rate that exceeds 120 bpm within 10 minutes of standing up.(7) In addition to the fast heart rate and light-headedness, there are a number of other symptoms associated with POTS. (See below.)

POTS is generally classified into four different types. There's some discussion about where to draw the lines around these categories, but these are generally accepted. According to Johns Hopkins medicine, a "person with POTS may experience more than [one] of these at the same time"(6) with symptoms varying from person to person.

Neuropathic POTS--associated with small fiber nerves that regulate the constriction of the blood vessels in the limbs and abdomen. If these nerves aren't working properly, it can be difficult to get blood vessels to move the blood along.

Hyperadrenergic POTS--this type of POTS is associated with elevated levels of norepinephrine, the stress hormone

Hypovolemic POTS--a type of POTS associated with abnormally low levels of blood

Primary POTS--this is when POTS occurs with no other condition present (compare to secondary POTS below); also called "idiopathic POTS."(8)

Secondary POTS--this type of POTS is seen in patients who also have a condition (or conditions) known to cause issues with the autonomic nervous system, such as Chiari malformation, multiple sclerosis, mast cell activation disorders, diabetes, autoimmune disorder, and others. There is also a strong association between POTS and joint hypermobility disorders, such as Ehlers-Danlos Syndrome. There has been recent research showing an overlap between POTS, joint hypermobility, and mast cell disorder.(6,8)

What are the symptoms of (POTS)?

Each case of POTS is different. Because POTS is caused by some abnormality in the autonomic nervous system, other autonomic issues can occur.

POTS symptoms can:

• develop gradually or come on suddenly.

• happen immediately or a few minutes after sitting or standing.

• sometimes resolve after lying down.

• be different at different times of day.(7)

• often being in puberty.(6)

• NOT be caused by anxiety alone.(6)

• can come and go for a wide variety of reasons including age, diet, medication, physical activity, weather, hydration status, and more.(1)

Common POTS Symptoms Include: (1,6,7,8,9)

• Dizziness or lightheadedness, especially when standing, during prolonged standing, or on long walks

• Fainting or near fainting (which is helpful, in a way, as it makes the person return to a flat position, and the blood can more easily return to the heart and brain.(9))

• Severe and/or long-lasting exhaustion or fatigue

• Exercise intolerance or worsening of symptoms after increased activity

• Forgetfulness, trouble focusing, trouble paying attention, problems thinking (brain fog)

• Heart palpitations (forceful heartbeats, a racing heart rate, and/or skipped heartbeats)

• Feeling nervous or anxious

• Shakiness/tremors

• Excessive sweating

• Shortness of breath

• Chest pain

• Headaches

• Blurry vision and/or tunnel vision

• Dimming of vision

• Feeling sick

• Problems with stomach or digestion, such as nausea, diarrhea, constipation, vomiting, bloating, stomach pain

• Bloating

• Small fiber neuropathy

• Coldness or pain in the extremities

• Blood pooling in the extremities

• A pale face and purple discoloration of hands and feet if they're lower than the level of the heart

• Disrupted sleep from chest pain, racing heart rate, and excessive sweating

The following can often make POTS symptoms worse: (1,6,7,9)

• Being in warm environments, like a bath or shower or warm climate

• Standing frequently and for a prolonged period, such as waiting in line or showering or sitting at a desk for long periods of time

• Emotionally stressful events

• Participating in strenuous exercise or physical labor

• Inadequate salt or fluid intake, such as after skipping a meal

• Eating, since blood is directed to the digestive system

• Being sick (cold/flu/infection)

• Menstruation (some women report worsening symptoms right before their menstrual period (7))

• Drinking alcohol

• Resting too much

POTS is not fatal, but people with POTS may have an increased risk of falls and related injuries due to fainting

What are the causes and risk factors for POTS?

POTS is a common condition, affecting between one and three million Americans6 and millions more around the world8. Dysautonomia International says "expert estimate that the POTS population has doubled since the start of the COVID-19 pandemic" as POTS is often seen in long COVID patients. Most people with POTS (80-90% by some estimates (8,9)) are women and people assigned female at birth between the ages of 15 and 50, according to Cleveland Clinic. (Other sources cite the age group of 12 to 50.9) However, Cleveland Clinic adds, men and people assigned male at birth can have POTS, too. POTS also impacts one in every 100 teens.(9) There is nothing to do to prevent POTS from occurring, as researchers are still trying to understand the cause(s) of POTS.(6) 

Some of the common stressors that can cause POTS to flare up for the first time or make it worse are:(1,9)

• A significant illness, like a viral illness or serious infection

• Pregnancy

• Physical trauma, such as a head injury

• Surgery

• Having certain autoimmune conditions, such as Sjogren's syndrome, lupus, and celiac disease

• Having little room for the spinal cord in the neck or as it emerges from the skull (like Chiari malformation)

 Diagnosis and Treatment for POTS

Because POTS symptoms vary from person to person, can develop slowly, can look different at different times, and mimic a number of other conditions, it can take months or years to receive a POTS diagnosis.

The type of medical providers who diagnoses POTS can vary as well. Some people are diagnosed by their primary care provider while others see a specialist, such as a neurologist, a cardiologist, a vasculature specialist, or a provider at a headache clinic. Patient often see multiple medical providers to put the pieces of the POTS puzzle together.

The provider will take the patient’s history and ask questions about current symptoms. They will also perform a physical exam and possibly order bloodwork.

The main way to diagnose POTS is with a ten-minute standing (or active standing) test(6) or a tilt-table test (also called a "passive head-up tilt test" or "head-upright tilt test.")(4)  The tilt-table test can imitate what happens in the body when a person stands up after lying down. The patient lies down on a table, and the table is then raised to a nearly upright position, mimicking the person standing up. The patient remains safe, even if they faint, as straps keep them from falling. Heart rate, blood pressure, and other vital signs are monitored during the test to determine if the patient meets the parameters for a POTS diagnosis.

If a tilt-table test is not available, an active standing test may be used. In this test, a patient's heart rate and blood pressure are taken while lying down, and then again after standing for two minutes, again after standing for five minutes, and lastly, after standing for ten minutes. This test can miss some cases of POTS, so it is best used in conjunction with symptomology and other testing.(8)

Other tests for specific symptoms of POTS may include:(1,8)

• Urine tests

• Quantitative sudomotor axon reflex test (QSART) that evaluates the nerves associated with sweating(5)

• Autonomic breathing test

• Thermoregulatory sweat test (TST)

• Skin nerve biopsy, looking at the small fiber nerves

• Echocardiogram

• Blood volume with hemodynamic studies

• Gastric mobility studies

• Valsalva maneuver

• 24-hour blood pressure & heart rate monitoring

• Magnetic resonance imaging (MRI)

Just like each case of POTS is individual, the treatment for POTS will be individualized based on the most troublesome symptoms and what works for each patient.

Treatments can include:

Exercise, physical activity, and/or physical therapy

• The cardiac rehab model of exercise and reclined aerobic exercise has been helpful for some POTS patients.

• Gentle exercise like walking, yoga, aquatic therapy, jogging, Pilates, isometric exercises

• Base exercise on patient tolerance rather than a rigid plan

• Start slowly and increase as tolerance does

• Manual therapy before helps tolerate exercise that may have led to a flare-up in the past(9)

Diet and nutrition

• Increase water to two to three liters per day.8 

• Increase salt intake to 8,000 mg to 10,000 mg per day.8 

-- Salt helps keep fluid in the blood vessels and maintain a health blood pressure in some people with POTS. In others, it can cause high blood pressure.(9)

--- Eat salty snacks

--- Eat smaller meals and a balanced diet. High carb meals can reduce blood vessel constriction.(9)

--- Avoid alcohol. It can lead to dilation of the veins and loss of fluids.(9)

--- Possibly avoid caffeine as it can make some people with POTS more nervous and lightheaded, while others receive help with blood vessel constriction.(6)

Medical compression stockings (waist-high work best; knee-high help somewhat)(9)

When feeling dizzy or faint, move to one of these positions or do one of these motions to aid the blood vessels in constricting and moving blood back to the brain:(7,9)

• Lying down and raising the legs

• Crossing legs with one in front of the other while standing

• Rocking up and down on toes

• Clenching butt and stomach muscles

• Clenching fists

• Squatting

• Standing with one leg on a chair

• Bending forward from the waist

• Sitting in the knee-chest position

• Sitting in a low chair

• Leaning forward with hands on the knees when sitting

Practice good sleep hygiene:

• Set the room to an ideal temperature, usually a little cooler

• Follow a consistent sleep schedule

• Avoid daytime napping. If you do need to nap, try to keep it under an hour.

• Avoid excessive television, phone, or computer use in bed.

There aren't any medications approved by the FDA for POTS treatment. However, the following medications are sometimes used off-label to help with POTS symptoms.(1,7,8,9) While they may work in the short term, it is uncertain whether they work in the long-term.(7)

• Fludrocortisone (Florinef)

• Pyridostigmine bromide (Mestinon)

• Midodrine (Proamatine)

• Beta-blockers (atenolol, propranolol, nadolol)

• Selective serotonin reuptake inhibitors (SSRI) (fluoxetine [Prozac], sertraline [Zoloft], escitalopram [Lexapro])

• Serotonin-norepinephrine reuptake inhibitors (SNRI) (venlafaxine [Effexor], duloxetine [Cymbalta])

• Clonidine (Catapres)

• Benzodiazepines

• Erythropoietin

• Octreotide

• Oral contraceptive pills

• Vasopressin

• Angiotensin converting enzyme inhibitors/angiotensin receptor blockers

• Stimulants (Ritalin, Dexedrine)

• Modafinil (Provigil)

• Pseudoephedrine (Sudafed)

Medications to avoid include narcotics (like codeine, morphine, oxycodone) and phenothiazine anti-emetics (like Phenergan and Compazine) as they can lead to more blood pooling, says Dr. Rowe. Niacin can cause vasodilation (this is when blood vessels have a difficult time constrict as they become wider, or dilated), he continues, and tricyclic antidepressants (like nortriptyline and amitriptyline) can cause hypotension in high doses.(9) A patient, their medical providers, and other loved ones can use a variety of methods to help the person with POTS live a comfortable, enjoyable life.

1.     https://my.clevelandclinic.org/health/diseases/16560-postural-orthostatic-tachycardia-syndrome-pots

2.     https://neuroscientificallychallenged.com/glossary/autonomic-nervous-system

3.     www.dysautonomiainternational.org/pdf/RoweOIsummary.pdf

4.     https://my.clevelandclinic.org/health/diagnostics/17043-tilt-table-test

5.     https://my.clevelandclinic.org/health/diagnostics/16398-quantitative-sudomotor-axon-reflex-test-qsart

6.     https://www.hopkinsmedicine.org/health/conditions-and-diseases/postural-orthostatic-tachycardia-syndrome-pots

7.     https://www.ninds.nih.gov/health-information/disorders/postural-tachycardia-syndrome-pots

8.     https://www.dysautonomiainternational.org/page.php?ID=30

9.     https://www.dysautonomiainternational.org/pdf/10FactsAboutPOTS.pdf