What is Postural Orthostatic Tachycardia Syndrome (POTS)?

What is Postural Orthostatic Tachycardia Syndrome (POTS)?

POTS is a chronic autonomic disorder characterized by an excessive heart rate increase of ≥30 bpm (≥40 bpm in adolescents 12-19 years) within 10 minutes of standing, without orthostatic hypotension, accompanied by debilitating symptoms of orthostatic intolerance. 1, 2

Core Diagnostic Features

POTS requires three essential components to be present simultaneously:

• Heart rate criteria: A sustained increase of ≥30 bpm within 10 minutes of standing or head-up tilt (≥40 bpm for ages 12-19 years), with standing heart rate often exceeding 120 bpm 1, 2
• Absence of orthostatic hypotension: No sustained systolic blood pressure drop ≥20 mmHg or diastolic drop ≥10 mmHg within 3 minutes of standing 1, 2
• Symptoms of orthostatic intolerance: Lightheadedness, palpitations, tremulousness, generalized weakness, blurred vision, and fatigue that develop upon standing and improve rapidly when returning to supine position 1, 2

Clinical Presentation

Cardiovascular symptoms include palpitations, chest pain, and the characteristic rapid heartbeat upon standing 3, 4

Neurological symptoms encompass dizziness, lightheadedness, "brain fog" (cognitive difficulties), headaches, and visual disturbances such as blurring or tunnel vision 2, 5, 4

Systemic symptoms include profound fatigue, lethargy, exercise intolerance, and physical deconditioning 2, 5, 4

Gastrointestinal symptoms such as nausea, bloating, abdominal pain, and diarrhea frequently accompany POTS 1, 5

Musculoskeletal symptoms including generalized weakness and pain are common 5

Patient Demographics and Triggers

POTS predominantly affects females (approximately 80%) of childbearing age, typically presenting between ages 15-45 years 5, 4

Common precipitating factors include viral infections, vaccination, trauma, pregnancy, surgery, or significant psychosocial stress 5, 4

The syndrome has gained particular attention as a post-acute sequela of COVID-19 (PASC POTS), where symptoms persist ≥3 months after acute infection 1

POTS is frequently associated with joint hypermobility syndrome, chronic fatigue syndrome, recent infections, and physical deconditioning 1, 6

Pathophysiologic Subtypes

Three primary phenotypes exist, each requiring different management approaches: 7, 8

• Neuropathic POTS: Results from partial autonomic neuropathy causing impaired peripheral vasoconstriction during orthostatic stress, leading to excessive venous pooling 7, 8
• Hyperadrenergic POTS: Characterized by excessive norepinephrine production or impaired reuptake causing sympathetic overactivity 7, 8
• Hypovolemic POTS: Involves central hypovolemia with compensatory reflex tachycardia, often triggered by dehydration and deconditioning 7, 8

Diagnostic Testing Requirements

The active stand test is the primary diagnostic method: Measure blood pressure and heart rate after 5 minutes supine, then immediately upon standing and at 2,5, and 10 minutes while standing quietly 2

Critical testing conditions must be maintained: Perform testing in a quiet environment at 21-23°C, with patients fasted for 3 hours and avoiding nicotine, caffeine, theine, or taurine-containing drinks on the day of examination, ideally before noon 2

Common diagnostic pitfalls to avoid: Failing to complete the full 10-minute stand test may miss delayed heart rate increases; not distinguishing POTS from inappropriate sinus tachycardia or other arrhythmias leads to misdiagnosis 2

Tilt-table testing serves as an alternative if the active stand test is inconclusive 2

A 12-lead ECG should be obtained to exclude arrhythmias or conduction abnormalities 2

Exclusion Criteria

POTS cannot be diagnosed if the tachycardia is explained by: anorexia nervosa, primary anxiety disorders, hyperventilation, anemia, fever, pain, active infection, dehydration, hyperthyroidism, pheochromocytoma, or use of cardioactive drugs (sympathomimetics, anticholinergics) 1

Severe deconditioning from prolonged bed rest must also be excluded as the primary cause 1

Prognosis and Natural History

Approximately 50% of patients experience spontaneous recovery within 1-3 years, though many remain significantly disabled 5

The prevalence ranges between 0.2% and 1.0% in developed countries 5

POTS significantly impairs quality of life through reduced exercise capacity, physical deconditioning, and inability to maintain upright posture for normal daily activities 7, 5, 4