POSTURAL TACHYCARDIA SYNDROME (POTS) 101

POSTURAL TACHYCARDIA SYNDROME (POTS) 101


Improved recognition of Postural Tachycardia Syndrome (POTS) over the past decade has led to more diagnoses – and more questions. The goal of this post is to provide a brief introduction to POTS, define some of the terms, and describe some of the clinical features.

DEFINITIONS

Tachycardia means fast heart rate. Postural tachycardia means an increase in heart rate that is related to standing up. Sometimes the word orthostatic is used instead of postural – both mean standing or upright. POTS patients have daily symptoms caused by standing, called orthostatic intolerance (difficulty tolerating standing). Hypotension refers to a drop in blood pressure, the opposite of hypertension which is a rise in blood pressure. Syncope (also called fainting) is defined as a brief loss of consciousness caused by hypotension and a lack of blood flow to the brain. Syncope is always followed by spontaneous and complete recovery. The causes of syncope can be benign (for example, prolonged standing or the sight of blood), but heart problems must be excluded. Presyncope is the sensation that syncope (fainting) is coming. Some individuals can prevent syncope by immediately sitting down or lying down when they recognize presyncope symptoms.

DIAGNOSIS

Patients with POTS have (A) an abnormal increase in heart rate (without hypotension) when they stand and (B) daily symptoms related to standing.¹

Tilt-table testing is the standard method of diagnosing POTS. When humans stand, the muscles in their bellies, thighs, and legs contract. Contraction of the muscles squeezes the blood vessels and pushes the blood from the legs and belly back up to the heart. This muscle-pumping action counters the effects of gravity which pulls blood down. During a tilt-table test, the patient is tilted upright 60-70 degrees, but the muscles involved in standing remain relaxed, so blood is not pumped back up to the heart. For adults (>19 years of age), POTS is diagnosed when the tilt test causes a symptomatic increase in heart rate of 30 beats per minute compared to lying flat. In younger people (≤19 years), the heart rate must increase by 40 beats per minute to be diagnostic of POTS.² The tilt-table test is safe, but symptoms can occur.

Some healthcare providers will use a standing test instead of a tilt-table test. During a standing test the patient lies flat for a period of time and then stands for a period of time while the heart rate and blood pressure are monitored.

CLINICAL FEATURES

POTS disproportionately affects young women. Adolescents with POTS might develop symptoms shortly after the onset of puberty or following growth spurts or illnesses. The symptoms that patients with POTS can develop when they stand include lightheadedness, headache, nausea, visual changes, sweating, difficulty breathing, anxiety, confusion, abdominal discomfort, and presyncope. Patients with POTS can have syncope, but the POTS diagnosis is not based on the presence or absence of syncope. Some patients develop a bluish discoloration of their feet and legs when they stand, referred to as acrocyanosis.

NEXT STEPS

If you or a loved one seems to have features of POTS, please tell your healthcare provider so that appropriate testing can be done.

The next POTS post will discuss some basic treatments. A third post will discuss recent research that shows how POTS symptoms and panic symptoms are different.

References

¹ Stewart JM, Boris JR, Chelimsky G, Fischer PR, Fortunato JE, Grubb BP, Heyer GL, Jarjour IT, Medow MS, Numan MT, Pianosi PT, Singer W, Tarbell S, Chelimsky TC; Pediatric Writing Group of the American Autonomic Society. Pediatric Disorders of Orthostatic Intolerance. Pediatrics. 2018;141: doi: 10.1542/peds.2017-1673

² Singer W, Sletten DM, Opfer-Gehrking TL, Brands CK, Fischer PR, Low PA. Postural tachycardia in children and adolescents: what is abnormal? J Pediatr. 2012;160:222-226.