Postural orthostatic tachycardia syndrome

Postural orthostatic tachycardia syndrome (POTS)
Other names	Postural tachycardia syndrome
Specialty	Cardiology, neurology
Symptoms	Lightheadedness, trouble thinking (brain fog), blurry vision, weakness when standing
Usual onset	Typically around age 20
Duration	More than 6 months
Causes	Variable
Risk factors	Family history
Diagnostic method	An increase in heart rate by 30 beats per minute upon standing
Differential diagnosis	Dehydration, heart problems, adrenal insufficiency, Parkinson's disease
Treatment	Avoiding factors that trigger symptoms, increasing dietary salt and water intake, wearing compression stockings, exercise, cognitive behavioral therapy, medications such as beta blockers, pyridostigmine, midodrine, and fludrocortisone
Prognosis	Approximately 90% of patients improve with treatment
Frequency	Approximately 500,000 people in the US

Postural orthostatic tachycardia syndrome (POTS) is a condition that affects the flow of blood through the body, causing dizziness when standing. It occurs because the autonomic nervous system, which regulates body functions, doesn't respond correctly to standing. Symptoms can range from mild to severe.

Blood pressure measurement, an important factor in diagnosing POTS

Definition and Overview

POTS is a form of orthostatic intolerance, a condition in which the body's response to changing from lying down to standing leads to uncomfortable symptoms, most notably lightheadedness, fainting, and rapid heartbeat. It is defined by excessive heart rate increments upon upright posture. A person with POTS will experience heart rates that increase at least 30 beats per minute in adults, or 40 beats per minute in adolescents, with standing, alongside other symptoms of the disorder.

Causes and Risk Factors

The exact cause of POTS is unknown. However, it often starts after a major stressor such as trauma, major surgery, or a viral illness. It may also have a genetic component, as it sometimes runs in families.

Certain conditions seem to predispose individuals to POTS, including diabetes, multiple sclerosis, lupus, some forms of hypermobility, and more. It's most often seen in young women, and can be associated with extreme fatigue and intolerance to exercise.

Symptoms

Symptoms of POTS can vary from person to person, but generally include faintness or lightheadedness; rapid heartbeat or palpitations; chest pain; headache; fatigue; shortness of breath; sweating; nausea or vomiting; exercise intolerance; and sleep disturbances. Some individuals may also experience "brain fog" – problems with short-term memory, concentration, or cognitive function.

Diagnosis

POTS is typically diagnosed through a variety of tests, the most common of which is a tilt table test, which monitors blood pressure, heart rate, and symptoms in response to changes in posture and position. Other tests may include blood tests, electrocardiograms, and tests for conditions that can cause similar symptoms.

Treatment

Treatment of POTS is usually focused on relieving low blood volume or regulating circulatory problems that could be causing the condition. This can involve a combination of medication, physical therapy, and lifestyle modifications. Medications may include beta blockers, fludrocortisone, or midodrine, while lifestyle changes often involve increased fluid and salt intake, regular physical activity, and avoidance of triggers.

Pathophysiology

The underlying pathophysiology of POTS is complex and not completely understood. It's believed to involve dysfunction in the autonomic nervous system (which controls the "automatic" functions of the body like heart rate, digestion, and blood pressure), particularly its control of the sympathetic nervous system. This can result in abnormal control of heart rate and blood pressure.

Multiple mechanisms seem to be involved in the pathophysiology of POTS, with different patients experiencing different causes. These can include hypovolemia (low blood volume), peripheral denervation, hyperadrenergic states, and abnormal venous pooling.

Complications

POTS can significantly impact a person's quality of life, and severe cases may lead to disabling symptoms. Complications can arise from the associated symptoms of POTS, such as fainting and falls from the rapid increase in heart rate and drop in blood pressure. Long-term effects can include deconditioning due to lack of physical activity.

Prognosis

The prognosis for POTS varies between individuals. Some people may see improvement in their symptoms with treatment and lifestyle modifications, while others may experience symptoms for many years. A subset of patients may experience a remission of symptoms, particularly those whose POTS onset occurred during adolescence.

Prevention

Prevention of POTS primarily focuses on managing and avoiding triggers. This can include maintaining adequate hydration, avoiding standing for prolonged periods of time, and incorporating regular physical activity into the daily routine.

References

• Sheldon, R. S., Grubb, B. P., Olshansky, B., Shen, W. K., Calkins, H., Brignole, M., Raj, S. R., Krahn, A. D., Morillo, C. A., Stewart, J. M., Sutton, R., Sandroni, P., Friday, K. J., Hachul, D. T., Cohen, M. I., Lau, D. H., Mayuga, K. A., Moak, J. P., Sandhu, R. K., & Kanjwal, K. (2015). 2015 Heart Rhythm Society Expert Consensus Statement on the Diagnosis and Treatment of Postural Tachycardia Syndrome, Inappropriate Sinus Tachycardia, and Vasovagal Syncope. Heart Rhythm, 12(6), e41-e63

See Also

Dysautonomia Orthostatic intolerance Syncope

External links

• National Center for Advancing Translational Sciences: Postural Orthostatic Tachycardia Syndrome
• National Organization for Rare Disorders: Postural Orthostatic Tachycardia Syndrome

Classification	ICD-10: I49.8 ICD-9-CM: 337.9 MeSH: D054972 SNOMED CT: 371073003

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