Orthostatic Intolerance Clinical Presentation

Updated: Nov 13, 2019
  • Author: Julian M Stewart, MD, PhD; more...
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Postural tachycardia syndrome (POTS)

Quality of life can be severely compromised in patients suffering from POTS. A few features are common to all variants.

The onset often follows a flu-like illness. Illness may occasionally represent a self-limited autoimmune disease. [13] The role of immune and epigenetic factors remains ill-defined. Some patients have an insidious onset over years, sometimes with a past history of vasovagal syncope (VVS). Some patients have joint hypermobility syndromes. [92] While supine or seated, some patients appear well while others appear pasty and pale. Many patients are unable to remain upright for long periods of time and experience symptoms similar to the prodrome of VVS. BP is typically well maintained and may increase when upright in hyperadrenergic individuals. Prolonged laboratory tilt may provoke VVS.

Cognitive deficits and exercise intolerance are prominent complaints [93] and gastrointestinal symptoms such as dysmotility are reported. [94] Young women may be underweight, and POTS must be differentiated from eating disorders, which can produce POTS-like OI in early stages.

Environmental heat reroutes blood to the skin and makes patients worse. Air conditioning may be required and standing in hot showers untenable. School work may be impaired, and home schooling is common. Colleges are often accommodating because of adaptive scheduling and improved logistics.

A wide variety of pharmacologic therapies are recommended with variable effects including beta ß-blockade, a-1 agonists (midodrine), acetylcholinesterase inhibitors (pyridostigmine), and fludrocortisone acetate (florinef).

Water ingestion is a useful short-lived palliation. [95] Effects are through TRPV4 receptors in the splanchnic vasculature, [96] and ingestion of 16 ounces of water and waiting 20-30 minutes yields benefit for hours. Salt and water loading can help but are often difficult to accomplish.

Even when the cause is known (e.g., NET deficiency) pharmacologic treatment is rarely curative. Most young people improve over time; in others POTS persists.

Postural syncope (vasovagal syncope, acute OI, simple faint)

The initial evaluation of a patient presenting with syncope comprises a detailed history, physical examination, including orthostatic BP measurements, and an electrocardiogram to look for QT prolongation, pre-excitation, and arrhythmia. Obtaining a detailed history is paramount. Historical details that point towards reflex syncope [54] include a history of similar recurrent episodes, whether episode(s) occur exclusively when upright or with change in position, whether they are related to activity such as urination, defecation, deglutition, hair-grooming, or stretch, whether there are predisposing factors such as fear, noxious stimuli, environmental heat, immobilization, whether they follow exercise and whether they are preceded by the prodrome of OI (e.g., nausea, seating, pallor) – a more gradual onset (many seconds to minutes) favors reflex syncope as does a post-drome of pallor, fatigue, and confusion. History that favors an increased likelihood of cardiac syncope include antecedent heartdisease, family history of sudden death, known arrhythmia or arrhythmia risk such as long QT syndrome or pre-excitation, an arrhythmogenic medication history, palpitations preceding the episode, and episodes that occur abruptly, during exercise, or when supine.


Physical Examination

Some patients with postural tachycardia syndrome (POTS) may appear pale and malperfused. The majority have a normal appearance as do patients suffering from vasovagal syncope (VVS). A POTS patient, on average, has an increased heart rate. Blood pressure should be normal for age although reports of patients with constitutional low blood pressure exist and can potentially relate to epigenetic down-regulation of tyrosine hydroxylase synthesis. A 10-minute standing test following prolonged recumbency has been validated in adults with POTS but not in children and adolescents. It is important to note that the HR change on orthostasis should not be used alone as the criterion for POTS; symptoms must be present. A 3-minute standing BP test for neurogenic orthostatic hypotension (NOH) has been validated across ages.