Postural Orthostatic Tachycardia Syndrome: A Consideration in Orthostatic Intolerance
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Expires April 30, 2015
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Postural orthostatic tachycardia syndrome may not be the first disorder that clinicians consider when they encounter a patient with orthostatic intolerance, but ignoring this possibility during a differential diagnosis can mean patients continue to experience unexplained dizziness, fatigue, syncope, and a variety of other related signs and symptoms. Arriving at the correct diagnosis will allow you to help patients manage the condition and return to the lives and activities they previously enjoyed.
TESTING AND REFERRAL
An appropriate workup for POTS includes a complete and thorough history plus a comprehensive physical examination. This includes reviewing the patient’s medication list for any medications or combinations of medications that cause cerebral hypoperfusion, volume depletion, tachycardia, or peripheral vasodilation.2 It is essential to explore the family history for genetic disorders12 and to take a detailed social history, including lifestyle habits that may reproduce the symptoms of POTS.
The definitive diagnosis of POTS is made with a tilt-table test. Obtaining in-office orthostatic vitals can substantially increase the index of suspicion for the syndrome. The procedure used to obtain orthostatic vitals varies by institution. However, every protocol includes a period of rest in a supine position, after which the patient is asked to stand and the blood pressure and pulse are measured after a specified number of minutes. If the patient becomes symptomatic on standing, the blood pressure remains unchanged, and the pulse is elevated to at least 30 beats/min from the supine pulse or greater than 20 beats/min after 10 minutes, a diagnosis of POTS must be considered. Unless a more common cause of the tachycardia is found and treated to resolution, tilt-table testing should be ordered to evaluate these patients for POTS.
If POTS is suspected once the history and physical are completed, the patient should be referred to cardiology or neurology for tilt-table testing to confirm the diagnosis. Laboratory testing should include, but not be limited to, a complete blood count with differential, a comprehensive metabolic panel, Westergren sedimentation rate, and thyroid testing. Adrenal testing,11 a search for vitamin deficiencies, autoimmune diseases, and infective causes (eg, Lyme disease and cytomegalovirus), and urinalysis may also be appropriate based on the patient history and presentation.14
Broad ancillary testing and referral may be needed in patients with POTS. According to Giesken,14 an ECG, echocardiogram, cardiac event monitoring, and an evaluation by a cardiologist are essential. Pasupuleti and Vedre17 recommend referral to a neurologist for evaluation for peripheral and central lesions with electromyography and MRI. Depending on the practice, tilt-table testing may be available through either specialty and may guide the work-up. Referrals to an endocrinologist, a rheumatologist, and a nephrologist to evaluate hyperadrenergic states, autoimmune dysfunction, and kidney disease should be considered as well.14,16 Referrals and additional tests may be necessary, even if secondary causes of POTS are not identified. These tests, although extensive and expensive, may help determine the best and most appropriate treatment options to control the patient’s symptoms and restore quality of life.
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