The Purple Book

Postural Orthostatic Tachycardia Syndrome (POTS)

A chronic and disabling disorder of orthostatic intolerance, characterised by excessive HR increase without hypotension after rising to upright posture

Definition

Consensus definition:

1. A sustained HR increment of not less than 30bpm within 10min of standing or head-up tilt. For individuals who are 12-19yo, the required HR increment is at least 40bpm; and
2. An absence of orthostatic hypotension (i.e. no sustained systolic blood pressure [BP] drop of 20 mmHg or more); and
3. Frequent symptoms of orthostatic intolerance during standing, with rapid improvement upon return to a supine position. Symptoms may include lightheadedness, palpitations, tremulousness, generalized weakness, blurred vision, and fatigue; and
4. Duration of symptoms for at least 3 months; and
5. Absence of other conditions explaining sinus tachycardia such as anorexia nervosa, primary anxiety disorders, hyperventilation, anemia, fever, pain, infection, dehydration, hyperthyroidism, pheochromocytoma, use of cardioactive drugs (e.g. sympathomimetics, anticholinergics) or severe deconditioning caused by prolonged bed rest.

Causes

POTS often co-exists with other pathology making the diagnosis of a separate entity difficult. Underlying causology not clear but postulates include:

• possible post-viral and therefore immunological cause
• possible neuropathic cause
• CVS deconditioning after prolonged rest
• hypovolaemia is commonly (up to 70%) observed in POTS
• possible genetic predisposition

Evaluation

• history to confirm exaggerated response to orthostatic change
• history to define co-morbidities or other mimics
• examination to confirm exaggerated orthostatic tachycardia without hypotension

Investigation

• investigation of co-morbidities and conditions which cause or mimic the autonomic syndrome
• basic bloods – electrolytes, FBC, TFT and ECG
• Tilt table testing may be appropriate
• other – depending on co-morbidities

Management

• education regarding hydration, exercise, post-prandial activity and environmental factors
• review of medications which affect HR – eg stimulants, SSRI’s etc
• Pharmacological, none of which proven:
  • fludrocortisone
  • β-blockers
  • ivabradine
  • midodrine