From the Guidelines
Postural Orthostatic Tachycardia Syndrome (POTS) is diagnosed when a person experiences an abnormal increase in heart rate upon standing, specifically a sustained heart rate increase of at least 30 beats per minute (or ≥40 beats per minute in individuals aged 12-19 years) within 10 minutes of standing or during a head-up tilt table test, without a corresponding drop in blood pressure. These symptoms must persist for at least 3 months and be accompanied by chronic symptoms that worsen with standing, such as lightheadedness, fatigue, brain fog, palpitations, exercise intolerance, and visual disturbances. For diagnosis, other causes of orthostatic symptoms and tachycardia must be ruled out, including dehydration, medications, acute blood loss, and other medical conditions 1. POTS is more common in women and often begins after a triggering event like viral illness, pregnancy, or trauma. The condition involves dysregulation of the autonomic nervous system, affecting blood vessel constriction and blood volume regulation, which explains why standing causes blood to pool in the lower extremities, reducing return to the heart and triggering compensatory tachycardia. Some key points to consider in the diagnosis of POTS include:
- A sustained increase in heart rate of ≥30 bpm within 10 min of moving from a recumbent to a quiet (nonexertional) standing position (or ≥40 bpm in individuals 12–19 y of age) 1
- The absence of orthostatic hypotension (>20 mm Hg reduction in systolic BP) 1
- Symptoms associated with POTS include those that occur with standing (e.g., lightheadedness, palpitations); those not associated with particular postures (e.g., bloating, nausea, diarrhea, abdominal pain); and those that are systemic (e.g., fatigue, sleep disturbance, migraine headaches) 1. It is essential to note that the diagnosis of POTS should be based on the most recent and highest quality evidence, and the criteria for POTS should be strictly followed to ensure accurate diagnosis and effective management.
From the Research
Diagnostic Criteria for POTS
The diagnostic criteria for Postural Orthostatic Tachycardia Syndrome (POTS) include:
- A heart rate increment of 30 beats/min or more within 10 minutes of standing or head-up tilt in the absence of orthostatic hypotension 2
- The standing heart rate is often 120 beats/min or higher 2
- Symptoms of orthostatic intolerance, such as fatigue, exercise intolerance, and gastrointestinal distress 3
- Excessive heart rate increase without hypotension during upright posture 3
Pathophysiologic Mechanisms
The pathophysiologic mechanisms of POTS include:
- Partial autonomic neuropathy 4
- Hypovolemia 4
- Hyperadrenergic state 4
- Impaired sympathetically mediated vasoconstriction 2
- Excessive sympathetic drive 2
- Volume dysregulation 2
- Deconditioning 2
Challenges in Diagnosis
There are challenges in diagnosing POTS, including:
- No single set of criteria is universally accepted 5
- Gaps in the present criteria used to identify individuals with POTS 5
- Reproducibility of physiological findings 5
- Relationship of symptoms to physiological findings 5
- Presence of symptoms alone without any physiological findings 5
- Response to various interventions 5