Postural orthostatic tachycardia syndrome (POTS) is a type of dysautonomia and blood circulation disorder characterized by different factors that vary depending on the individual when standing. Orthostatic Hypotension may seem like an accompanying condition of POTS – low blood pressure may seem like a natural symptom for someone with a blood circulation disorder.
Although POTS and OH are both syndromes of a broader range of conditions called orthostatic intolerance, POTS and OH can occur separately or together, and aren’t always indicative of dysautonomia or an autonomic nervous system disorder. Understanding the root cause of the orthostatic intolerance is important as this is what determines overall treatment.
Postural Orthostatic Tachycardia Syndrome (POTS)
POTS is a relatively common condition affecting one to three million Americans each year. POTS is a disorder of the autonomic branch of the nervous system, the part of the body that regulates bodily functions we don’t consciously control such as heart rate, blood pressure, sweating, and body temperature.
Generally, POTS is a grouping of symptoms characterized by lightheadedness, difficulty thinking and concentrating, headache, blurry vision, palpitations, tremors, nausea, fatigue, and intolerance of exercise. Along with those symptoms, POTS is also identified by a heart rate increase by at least 30 beats per minute (bpm) or over 120 bpm in adults when an individual transitions from a horizontal position to standing. This is measured during the first 10 minutes of standing.
For individuals with POTS, heart rate can increase for several different reasons. According to John Hopkins Health, heart rate increases from a combination of the following:
· Decreased blood in circulation
· Pooling of blood below the heart when standing upright
· Elevated stress hormones released from the adrenal glands and nerves
In a healthy individual, the body has several mechanisms that it uses in response to changes in blood pressure. For instance, when blood pressure shifts, the body releases hormones to help constrict blood vessels and increase heart rate to improve blood circulation to the brain.
For people with POTS, this mechanism doesn’t respond efficiently and results in blood pooling in the lower half of the body due to the natural pull of gravity. When the brain does not receive an adequate supply of blood and oxygen, it can result in lightheadedness, fatigue, and brain fog. When stress hormones are released because of this, heart rate increases. Individuals with POTS may have accompanying orthostatic hypotension, or they may not.
Orthostatic Hypotension (OH)
OH is a condition that causes a decrease in blood pressure within three minutes of an individual standing up from a seated or lying down position. OH can be caused by blood loss, dehydration, or an inadequate hormonal response to changes in blood pressure. It can also be caused by certain medications, or disorders to the neurological or endocrine systems.
OH can be acute or chronic, and underlying etiology can be nonneurogenic or neurogenic (nOH). Nonneurogenic OH is more common with young individuals and is unrelated to nervous system function – more commonly associated with dehydration or low blood volume. Neurogenic OH is associated with serious autonomic illness and can result from impaired vasoconstriction due to dysfunction of the autonomic nervous system and is commonly associated with Parkinson disease (PD), multiple system atrophy (MSA), and pure autonomic failure. This type of OH is due to inadequate hormone release and the prevention of vasoconstriction – the same mechanism for the underlying cause of tachycardia in POTS. Symptoms of OH include:
· Lightheadedness
· Blurred vision
· Dizziness
· Weakness
· Fatigue
· Neck pain
Due to the varying causes of OH, it is extremely possible for an individual to have OH unrelated to an autonomic nervous system condition like the nonneurogenic OH that was mentioned above. Nonetheless, POTS and OH are both considered syndromes of orthostatic intolerance, meaning they can manifest separately, or can be seen simultaneously.
To learn more about POTS and OH, visit the Dysautonomia International Website at www.dysautonomiainternational.com
Sources
Postural Orthostatic Tachycardia Syndrome (POTS). (n.d.). Retrieved September 11, 2020, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/postural-orthostatic-tachycardia-syndrome-pots
Evaluation and Management of Orthostatic Hypotension—American Family Physician. (n.d.). Retrieved September 11, 2020, from https://www.aafp.org/afp/2011/0901/p527.html
Stewart, J. M. (2013). Common Syndromes of Orthostatic Intolerance. Pediatrics, 131(5), 968–980. https://doi.org/10.1542/peds.2012-2610
Medical History may Help Exclude Other Causes for Symptoms Associated with nOH. (n.d.) Retrieved October 5, 2020, from https://www.nohmattershcp.com/diagnostic-considerations-of-neurogenic-orthostatic-hypotension/excluding-other-causes