Historical note and nomenclature
Postural orthostatic tachycardia syndrome (POTS) is an often disabling syndrome of symptomatic orthostatic tachycardia in the absence of orthostatic hypotension. POTS is a restricted sympathetic dysautonomia with neuropathic and central forms resulting from a constellation of different disorders. The syndrome has also been called orthostatic tachycardia, orthostatic intolerance, idiopathic orthostatic intolerance and postural tachycardia, neurocirculatory asthenia, mitral valve prolapse syndrome, irritable heart, and soldier's heart, among others. There is also clinical overlap with chronic fatigue syndrome, especially in adolescent cases (Stewart and Weldon 2000).
The symptoms of postural orthostatic tachycardia syndrome suggest a hyperadrenergic state and impaired cerebral perfusion. Presyncope is common with POTS, but less than a third of the patients experience syncope (Raj 2006). Chest discomfort may be a feature, but it is not associated with coronary artery stenosis (Raj 2006). Bowel irregularities are common, and many patients are co-diagnosed with irritable bowel syndrome. Orthostatic headache, when present in POTS, tends to be bifrontal, bitemporal, or holocephalic but occasionally may have a nuchal or occipital distribution, clearly distinct from the “coat-hanger” distribution sometimes seen with orthostatic hypotension and then attributed to trapezius ischemia (Mokri and Low 2003).
Symptoms of Postural Orthostatic Tachycardia Syndrome
(Particularly When Upright)
• Chest discomfort
• Exaggerated physiological tremor
• Cold sweaty extremities
• Exercise intolerance
• Lightheaded dizziness or presyncope
• Blurred or tunnel vision
• Headache, possibly migrainous
• Mental clouding (feeling “in a fog”; “brain fog”)
• Bowel irregularities
Diagnostic Criteria for Postural Orthostatic Tachycardia Syndrome
• Sustained heart rate increase of at least 30 beats per minute from supine to standing within 10 minutes of standing (or a heart rate that exceeds 120 bpm on standing)
• Lack of orthostatic hypotension (systolic blood pressure does not fall by more than 20 mmHg and may increase with standing)
• Symptoms of orthostatic intolerance (eg, lightheadedness, weakness, palpitations, blurred vision, breathing difficulties, nausea, or headache) develop with standing and resolve with recumbency
• Symptoms present for at least 3 months
• Occurs in the absence of prolonged bed rest (deconditioning)
• Occurs in the absence of medications that impair autonomic regulation (eg, vasodilators, diuretics, antidepressants, anxiolytic agents)
• Occurs in the absence of other conditions that might cause autonomic failure or orthostatic tachycardia (eg, active bleeding, anemia, dehydration)
(Raj 2006; Medow and Stewart 2007; Thieben et al 2007)
In addition to the orthostatic tachycardia, physical findings in postural orthostatic tachycardia syndrome can include a murmur or click of mitral valve prolapse (although significant mitral regurgitation is unusual) and prominent dependent acrocyanosis (Raj 2006). Dependent acrocyanosis, present in about half of patients with POTS, is characterized by a dark reddish-blue discoloration of the legs, which are cold to the touch (Raj 2006). This acrocyanosis is apparently due to decreased cutaneous blood flow rather than increased blood pooling in venous capacitance vessels (Freeman et al 2002; Stewart 2002; Raj 2006).
Symptoms may be exacerbated by fatigue, exercise, heat, dehydration, the postprandial state, menses, various medications, fibromyalgia, and migraine (Thieben et al 2007; Piovesan et al 2008; Staud 2008).
Postural orthostatic tachycardia syndrome primarily affects women of childbearing age, with 80% to 90% of cases being women, and most cases occurring between the ages of 15 and 50 years (Jacob et al 1999;(Mokri and Low 2003; Raj 2006; Garland et al 2007; Thieben et al 2007). Onset frequently occurs following pregnancy, major surgery, or presumed viral illness (Raj 2006). Symptoms in women are frequently exacerbated during the premenstrual phase of the ovulatory cycle (Raj 2006). A smaller proportion (10% to 15%) has a family history of orthostatic intolerance (Thieben et al 2007).
Although patients with postural orthostatic tachycardia syndrome may appear anxious, they do not have excess “cognitive anxiety,” nor do they have an increased lifetime prevalence of psychiatric disorders in general (Raj et al 2009).