The Autonomic Nervous System refers to the part of our brain and nerves that control all of our inner workings. From the latin term meaning “self-governing,” the autonomic nervous system serves as the brain’s “autopilot.” It controls your heart rate, blood pressure, body temperature, sweating, stomach and bowel function, and many other functions so that you don’t have to think about them.  The term dysautonomia refers to a condition associated with improper functioning of the autonomic nervous system.

The autonomic nervous system (abbreviated ANS) is divided into two functional branches. The part that is primarily concerned with the “fight or flight” reflexes (increased heart rate and blood pressure, increased sweating, decreased bowel function) is referred to as the Sympathetic Nervous System. The other branch is called the Parasympathetic Nervous System, and causes slowing of the heart rate, increased bowel function, and so on. It is active when a person is resting and relaxed. Most dysautonomia syndromes are triggered by the faulty operation of the sympathetic branch.

A specific form of dysautonomia is called the Postural Tachycardia Syndrome (or POTS). It affects millions of people around the world, and in the U.S. an estimated one to three million Americans have this condition.  POTS is characterized by an abnormal increase of the heart rate when the patient switches positions from lying to standing. It gives rise to “postural intolerance,” whereby people feel ill when they in normal people standing for any length of time, and the symptoms are relieved by lying down. POTS primarily affects young women, with about 5:1 ratio of females to males. The symptoms can start as a teenager or patients can develop it in their 20s or 30s. It can begin suddenly, often after an illness or an injury, or it can have a gradual onset.

POTS is NOT a disease. It is a “Syndrome.”  A syndrome is a group of symptoms that tend to occur together. POTS symptoms can be due to a large number of different underlying conditions.

Symptoms of POTS

The symptoms of POTS manifest when the subject stands upright, and disappear soon after the patient reclines. The symptoms include rapid heart palpitations, lightheadedness, fatigue, “brain fog,” shortness of breath, headache, and chest pains.  Some patients with POTS also suffer from nausea and vomiting, digestive problems, sweating problems (too much or too little), sleep disorders, cold and blue hands and feet, among others. There is a higher than normal incidence of fainting, migraines, and muscle aches/pains in patients with POTS.

Causes and Types of POTS

As POTS is not a disease but a manifestation of dysautonomia from some undiagnosed illness, finding the root cause may be the biggest challenge. In some cases it seems like it may occur after an infection, so there may be a component of “autoimmune” trigger to the syndrome. However, the more we learn of the syndrome the more complicated it seems to be. Patients have reported different experiences, which makes it hard to find common ground and point to a single cause.

Nonetheless, specialists try to classify POTS according to different factors like:

  • Hypovolemia and abnormal blood pressure – hypovolemia refers to a reduced volume of fluid circulating in the cardiovascular system. In hypovolemic patients, less blood returns to the heart while they are standing. For this reason, the heart does not fill adequately and has to pump rapidly to maintain proper circulation to the brain, leading to the tachycardic response, lightheadedness, “brain fog” and chronic fatigue.
  • “Hyperadrenergic” POTS  – about 20% of POTS patients have high levels of adrenaline or noradrenaline while standing up. These are the substances released by the sympathetic nervous system. Hyperadrenergic POTS patients tend to have higher blood pressures and are more likely to have tremors, headaches, and palpitations as a predominant symptom.
  • Genetic predisposition – some cases of POTS are associated with other genetic findings such as joint hypermobility or excessively elastic skin texture (Ehlers-Danlos Syndrome). This can lead to an abnormal amount of pooling of blood in the arms and legs. With less blood getting back to the heart, the heart has to pump faster to meet the body’s needs.
  • Inflammatory / collagen-vascular disease – diseases that cause body tissue inflammation such as Lupus or Sjogren’s Syndrome can be associated with symptoms of POTS
  • Viral illnesses – some patients diagnosed with POTS have had previous viral diseases or other infections such as Lyme disease, which may indicate a link between the two.
  • Mast Cell Activation Disorder (MCAD) – mast cells are specialized white blood cells that carry a substance known as histamine. Normally, they release histamine in response to a foreign protein such as pollen, which gives rise to the typical symptoms of hay fever. However, mast cells are found throughout the body. Some POTS patients seem to have “allergic” reactions to many substances, get skin rashes for no reason, and have predominant stomach symptoms. These POTS  patients may have a disorder where their mast cells release histamine inappropriately and that may cause many of their complaints. In those patients, antihistamines can make a big difference in the symptoms.

The Diagnosis

The way to diagnose POTS is to just have the patient stand up for 5-10 minutes and evaluate the change in heart rate and blood pressure in different positions. If the heart rate increases by more than 30 beats per minute (bpm) with going from a lying to a standing position, or if the standing heart rate hits 120 bpm (130 bpm in children), then POTS is present. Generally, the blood pressure should stay the same or go up a bit.  If the blood pressure drops more than 20 points with standing, then a diagnosis of “Orthostatic Hypotension” is more likely. Orthostatic hypotension is a different form of dysautonomia.

A more formalized standing test is known as a Tilt Table Test.  During a tilt test the patient is placed in an upright position at an angle of about 70 degrees using a tilting table, and then the heart rate and blood pressure are monitored continuously for up to 30 minutes. POTS specialists can perform a tilt test to confirm the diagnosis and obtain standing levels of adrenaline to see if the patient has the hyperadrenergic form of POTS. Tilt table testing is more often used to evaluate patients with fainting (“syncope”).

Depending on the symptoms, a specialist may run a series of studies to establish what might be causing the POTS.  Additionally, the doctor may recommend further testing to exclude other possible diseases that might show the same symptoms. These tests include an ECG or a heart monitor, which may indicate if another heart problem is causing the tachycardia, and an echocardiogram to ensure the heart is contracting properly and that the valves are working normally. Blood tests such as a hormonal test to exclude an overactive thyroid gland or an underactive adrenal gland are also appropriate.

There are a few doctors who specialize in POTS, and they tend to be from widely different medical specialties. Some POTS specialists are cardiologists or electrophysiologists with a special interest or expertise in the condition. Others may be neurologists, allergists, geneticists, or rheumatologists. You can find a list of doctors who care for POTS patients on the Dysautonomia Information Network.

Addressing the Issue

Many patients can keep the symptoms under control with changes in their daily lifestyle, as recommended by the doctor. The mainstays of therapy are drinking plenty of water, a high-salt diet, and exercise. Patients can use electrolyte drinks that have some salt in them, which will keep the blood pressure at normal levels. However, any fluid counts. Just remember that caffeine and alcohol work like diuretics and can cause a person to actually lose more fluid than they take in, so don’t overdo those beverages.

An increase in water intake will optimize the blood volume and promote better blood flow. For POTS patients, it’s essential to drink a glass or two of water right after they wake up to avoid lightheadedness. An even better “trick” is to have a large bottle of fluid on your nightstand and set your alarm clock 15 minutes early. When the alarm goes off, chug the fluid, then wait the 15 minutes before getting out of bed. One published guideline suggests POTS patients should be drinking between 3 and 4 quarts of fluid per day.

Salt is essential to allow you to retain the fluid that you drink. Unless you have high blood pressure, you need to consume gobs of salt! Salt tablets can supplement your intake of this necessary nutrient. Depending on the type of POTS you suffer from, the recommended salt intake may be as high as 10-12 grams per day.

Once people develop the symptoms of POTS, they don’t feel like doing anything. Long periods of physical inactivity can worsen the symptoms because of physical deconditioning. Exercise is the key to feeling better. Studies comparing exercise to medications have found that exercise is clearly better for you. If your POTS is severe then you need to exercise sitting down, as activities like walking, treadmill, or elliptical machines are usually not tolerated in the beginning. A recumbent bicycle is an ideal way to start building up your heart and your leg muscles. A rowing machine is also well-suited to the task. Swimming is excellent because the pressure of the water relieves some of the postural intolerance.

You should avoid large meals, because they require lots of time to be digested and a significant amount of blood is redirected towards the GI tract. To avoid that from happening, you should eat smaller meals more often. Also, avoid warm environments such as saunas, steam rooms or hot tubs. Try to keep moving, as the contraction of the leg muscles helps to push the blood in your leg veins back towards your heart and keep things circulating (this means of pushing the blood upwards is known as. Don’t stand in one spot for too long. And if you feel lightheaded, lie down, elevate your legs, and chug a large bottle of something liquid. In most cases, thigh-high or waist-high compression hose can help people function at work when they are expected to stand for a long time.

If the symptoms become unbearable, you should see a POTS specialist. Most primary care doctors have heard of POTS, but have little experience managing those patients medically.  Currently, there is no FDA-approved medication that can cure POTS, but there are many medications that can help alleviate the symptoms. Make sure that you see a doctor who is experienced in treating POTS patients, because most of the time people need multiple medications to help them feel more normal and be able to function.

Coping with POTS

With many cases remaining undiagnosed, the real prevalence of POTS is unknown. The good news is that the prognosis is favorable – within five years of diagnosis, 60% of the patients return to their previous functioning abilities. If there are any serious medical conditions that led to the syndrome of POTS, then treating the underlying condition is often the key to improving the symptoms.

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