What is Postural Orthostatic Tachycardia Syndrome (POTS)?
Postural orthostatic tachycardia syndrome (POTS) is a cardiovascular autonomic disorder characterized by an excessive heart rate increase of ≥30 bpm (≥40 bpm in adolescents aged 12-19) within 10 minutes of standing, occurring without orthostatic hypotension, accompanied by symptoms of orthostatic intolerance that improve when lying down. 1, 2
Core Diagnostic Features
POTS requires all five components to be present for at least 3 months 3:
- Heart rate criteria: Sustained increase of ≥30 bpm within 10 minutes of standing (≥40 bpm for ages 12-19 years), with standing heart rate often exceeding 120 bpm 1, 3
- Blood pressure criteria: Absence of orthostatic hypotension (no sustained systolic BP drop ≥20 mmHg or diastolic drop ≥10 mmHg) 1, 3
- Symptom profile: Frequent symptoms of orthostatic intolerance during standing that rapidly improve upon returning to supine position 3
- Duration requirement: Symptoms must persist for at least 3 months 2, 3
- Exclusion of alternative causes: Other conditions causing tachycardia must be ruled out 2, 3
Primary Clinical Presentation
Orthostatic Symptoms
The most prominent complaints include 2:
- Light-headedness and dizziness upon standing
- Palpitations and awareness of rapid heartbeat
- Generalized weakness and fatigue
- Blurred vision or tunnel vision
- Tremulousness
Autonomic Activation Signs
Sympathetic overactivity manifests as 2:
- Pallor and sweating
- Nausea
- Chest discomfort or pain
Additional Common Symptoms
Patients frequently report 2:
- Headache
- Exercise intolerance
- Cognitive difficulties ("brain fog")
- Sleep disturbances
- Postexertional malaise
Important caveat: Syncope is rare in POTS and typically occurs only when vasovagal reflex activation is triggered, not from POTS itself 3
Temporal Pattern and Triggers
- Characteristic pattern: Symptoms develop upon standing and are relieved by sitting or lying down 2
- Exacerbating factors: Symptoms worsen in the morning, with heat exposure, after meals, and with exertion 2
Demographics and Associated Conditions
- Typical patient: Predominantly affects young women of child-bearing age, with symptoms often first appearing in adolescence 2, 4
- Prevalence: Ranges between 0.2% and 1.0% in developed countries, with approximately 80% female predominance 5
- Precipitating factors: Onset often follows immunological stressors such as viral infection, vaccination, trauma, pregnancy, or surgery 2, 5
- Associated conditions: Frequently coexists with deconditioning, chronic fatigue syndrome, joint hypermobility syndrome, and hypermobile Ehlers-Danlos syndrome 2
Pathophysiological Subtypes
Three primary phenotypes have been identified, each with distinct mechanisms 6:
- Hyperadrenergic POTS: Excessive norepinephrine production or impaired reuptake leading to sympathetic overactivity
- Neuropathic POTS: Impaired vasoconstriction during orthostatic stress due to sympathetic denervation
- Hypovolemic POTS: Central hypovolaemia with reflex tachycardia, often triggered by dehydration and physical deconditioning
Critical Differential Diagnoses to Exclude
POTS must be distinguished from 2:
- Inappropriate sinus tachycardia
- Anxiety disorders
- Dehydration
- Anemia
- Hyperthyroidism
- Pheochromocytoma
Prognosis
Approximately 50% of patients spontaneously recover within 1-3 years, though the most affected patients may remain significantly handicapped despite treatment 5