Postural Orthostatic Tachycardia Syndrome or, 'POTS,' is one of a group of disorders with orthostatic intolerance as a main symptom people experience. Orthostatic intolerance (OI) involves a condition in which a person experiences an excessively reduced volume of blood returning to their heart as they stand from a lying down position. The main symptom of OI is lightheadedness, or even fainting. With POTS, the lightheadedness or fainting a person experiences is also accompanied by a quick increase in their heart rate of more than 30 beats per minute, or a heart rate in excess of 120 beats per minute within 10 minutes of their standing up.
Defined by excessive heart rate increments upon upright posture. A person with POTS will experience heart rates that increase 30 beats or more per minute upon standing and/or increase to 120 beats or more per minute upon standing (Grubb, 2000). These exaggerated heart rate increases usually occur within 10 minutes of rising.
The lightheadedness or fainting related to POTS can be relieved by lying down again. People from any age group can experience POTS, although 75-80% of the people who are affected by the syndrome are women between 15 and 50 years old. Some women have reported an increase in episodes of POTS right before menstruating. Pots many times starts after major surgery, trauma, pregnancy, or after a person experiences a viral illness. The syndrome can find people with an inability to exercise because it prompts dizziness or fainting.
The medical community remains unsure about what causes a reduction in the return of blood to a person's heart in OI, or why a person's heart starts to beat rapidly with POTS. Current thought is there are many mechanisms involved. Some people experience, 'peripheral denervation,' or neuropathic POTS while others present with symptoms that are due to sustained over-activity of their sympathetic nervous system referred to as, 'hyperadrenergic POTS.' Still others have POTS which is dominated by features of de-conditioning.
The tachycardic response of POTS is the hallmark symptom of the syndrome. At times it is accompanied by a decrease in the person's blood pressure and a number of additional symptoms which are associated with hypotension, although a person's blood pressure usually does not drop with POTS. Low blood pressure when a person stands is a completely different entity referred to as, 'orthostatic hypotension.' Low blood pressure related to any cause can prompt the following symptoms:
When a person experiences chronic or acute hypoperfusion of their organs and tissues in the upper parts of their body, it is believed to cause a number of other symptoms. These symptoms include the following:
Autonomic dysfunction is believed to cause people with POTS to experience a number of gastrointestinal symptoms which include:
People who have cerebral hypoperfusion in relation to POTS may also experience emotive and cognitive issues. Symptoms that persist while a person is in a recumbent position are hard to attribute to cerebral hypoperfusion and most likely reflect an element of fatigue or depression. With cerebral hypoperfusion, people with POTS can experience symptoms such as:
People with POTS who have levels of norepinephrine and epinephrine that are inappropriate can experience symptoms which are anxiety-like. These symptoms may include:
Unfortunately, the symptoms related to POTS, 'overlap,' considerably with the ones associated with generalized anxiety disorder. Due to this, a person may be misdiagnosed with an anxiety disorder instead of POTS. Despite this it is important to understand that prolonged inactivity related to any cause, particularly when a person spends a lot of time in a recumbent position, leads to a decrease in their orthostatic reflex. What this means is that chronic inactivity with frequent time spent in a recumbent position leads to the hallmark signs of POTS.
Questions are raised about POTS because of this fact in relation to some people. Some doctors wonder if POTS is an, 'epiphenomenon,' resulting from prolonged inactivity. Many people with POTS prefer to remain in a recumbent position, perpetuating a vicious cycle.
Several conditions are associated with POTS. Conditions such as restless leg syndrome, Ehlers-Danlos syndrome, chronic fatigue syndrome and others are associated with POTS. What follows are some descriptions of conditions associated with Postural Orthostatic Tachycardia Syndrome or, 'POTS.'
Many times, POTS is accompanied by, 'vasovagal syncope,' or, 'neurally mediated hypotension,' or, 'neurocardiogenic syncope.' Vasovagal syncope involves a fainting reflex caused by a profound drop in a person's blood pressure. An autonomic dysfunction that occurs with these disorders causes a person's blood to inappropriately pool in their limbs and away from their lungs, heart, and brain. The combination of misdirected blood flow and hypotension causes syncope (fainting). Tachycardia associated with POTS might be a cardiac response to restore a person's cerebral perfusion.
Medical science does not fully understand the causes of POTS.
The majority of people with the syndrome develop symptoms during adolescence as they experience a period of rapid growth, also finding themselves experiencing gradual improvement into their mid-twenties. Other people develop POTS after experiencing a bacterial or viral infection such as pneumonia or mononucleosis. Some people develop symptoms of POTS after a form of trauma such as an injury or a car accident. Women may also develop POTS either during or after pregnancy. In one test 12.5% of 152 people with POTS reported a family history of orthostatic intolerance, something that suggests there may be a genetic inheritance associated with the syndrome.
As of this time, no one has presented an explanation for POTS that may be applied to everyone who experiences the syndrome. There are some different theories:
Achieving a diagnosis of POTS can be difficult; a routine physical exam and standard blood testing do not indicate POTS. A tilt table test is crucial to achieving a diagnosis of POTS, although all of a person's symptoms have to be taken into consideration before a diagnosis is made. Tests to rule out things such as:
As well as a number of food allergies are commonly performed. A blood test might be performed to verify abnormally high levels of norepinephrine which are present in some people with POTS.
Therapies for POTS are aimed at relieving low blood volume, or regulating circulatory issues that may be causing the syndrome. There is no single treatment available that is effective for everyone who experiences POTS. Various medications appear to be effective on a short-term basis. It is uncertain whether or not these medications help over the long-term. Simple interventions to include ensuring an adequate intake of fluids, as well as adding additional salt to the person's diet, are many times effective.
The drugs midodrine and fludrocortisone in low does are often times used to increase a person's blood volume while narrowing their blood vessels. Consuming 16 ounces of water prior to getting up may also help to raise a person's blood pressure.
Some people are helped by beta-receptor blocking agents. There is also some evidence that an exercise program may gradually improve a person's orthostatic tolerance.
Postural Orthostatic Tachycardia Syndrome or, 'POTS,' might follow a relapsing-remitting course where a person's symptoms come and go over a period of years.
In the majority of instances, a person with POTS improves, although they commonly experiences some residual symptoms.