What is Postural Orthostatic Tachycardia Syndrome (POTS)?
POTS is a clinical syndrome of the autonomic nervous system where standing causes an excessive heart rate increase (≥30 bpm in adults, ≥40 bpm in adolescents 12-19 years) within 10 minutes, without a significant blood pressure drop, accompanied by debilitating symptoms of orthostatic intolerance that improve when lying down. 1, 2
Core Diagnostic Features
POTS requires all five components to be present simultaneously for at least 3 months 3, 1:
- 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, 2, 4
- Blood pressure criteria: Absence of orthostatic hypotension—no sustained systolic blood pressure drop ≥20 mmHg or diastolic drop ≥10 mmHg 3, 1, 2
- Symptom profile: Frequent symptoms of orthostatic intolerance during standing that rapidly improve upon returning to supine position 3, 1
- Duration requirement: Symptoms must persist for at least 3 months 3, 1
- Exclusion criteria: Absence of other conditions explaining sinus tachycardia such as anemia, hyperthyroidism, pheochromocytoma, fever, dehydration, or cardioactive drugs 3, 4
Clinical Presentation
Primary Orthostatic Symptoms
The hallmark symptoms develop upon standing and resolve with sitting or lying down 2, 4:
- Cardiovascular: Lightheadedness, dizziness, palpitations, rapid heartbeat, chest discomfort or pain 1, 4, 5
- Neurological: Generalized weakness, tremulousness, blurred vision, tunnel vision, cognitive difficulties ("brain fog") 3, 1, 4
- Autonomic activation: Pallor, excessive sweating, nausea 4
- Systemic: Profound fatigue, lethargy, exercise intolerance, shortness of breath 1, 4, 5
Associated Non-Specific Symptoms
Patients frequently report additional complaints beyond orthostatic intolerance 4, 6:
- Headache 1, 4
- Sleep disturbances 4
- Postexertional malaise 4
- Gastrointestinal disorders 6
- Musculoskeletal pain 6
Important caveat: Syncope is rare in POTS and typically occurs only when vasovagal reflex activation is triggered, not from POTS itself 1. If syncope is prominent, consider alternative diagnoses.
Demographics and Epidemiology
POTS predominantly affects young women aged 15-45 years, with approximately 80% female predominance 4, 6. The prevalence ranges between 0.2% and 1.0% in developed countries 6.
Pathophysiology and Subtypes
The condition has complex, multifactorial pathophysiology with three primary phenotypes 7, 6:
- Hyperadrenergic POTS: Excessive norepinephrine production or impaired reuptake leading to sympathetic overactivity 7
- Neuropathic POTS: Impaired vasoconstriction during orthostatic stress due to sympathetic denervation 7
- Hypovolemic POTS: Central hypovolemia and reflex tachycardia, often triggered by dehydration and physical deconditioning 7, 6
Precipitating Factors and Associated Conditions
The onset is typically precipitated by immunological or physical stressors 6:
- Viral infection (including COVID-19) 3, 6
- Vaccination 6
- Trauma or surgery 3, 6
- Pregnancy 6
- Psychosocial stress 6
POTS frequently coexists with 1, 4, 6:
- Physical deconditioning
- Chronic fatigue syndrome
- Joint hypermobility syndrome
- Hypermobile Ehlers-Danlos syndrome
Exacerbating Factors
Symptoms worsen with 4:
- Morning hours
- Heat exposure
- After meals
- Physical exertion
Prognosis
Around 50% of patients spontaneously recover within 1-3 years, though the most severely affected patients may remain significantly handicapped despite treatment 6.