Norepinephrine Transporter Deficiency in Postural Orthostatic Tachycardia Syndrome

Pathophysiological Mechanisms

• Different POTS phenotypes have been identified, including hypovolemic, neuropathic, and primary hyperadrenergic POTS, representing different pathophysiological mechanisms leading to orthostatic intolerance, as noted by the European Society of Cardiology 1, 2
• Primary hyperadrenergic POTS may be related to NET deficiency, characterized by excessive norepinephrine levels during orthostatic stress, according to the American Autonomic Society 2

Diagnostic Criteria

• POTS diagnosis requires an increase in heart rate ≥30 bpm (or ≥40 bpm in patients aged 12-19 years) within 10 minutes of standing or head-up tilt in the absence of orthostatic hypotension, as recommended by the European Society of Cardiology 4
• Common symptoms include dizziness, light-headedness, weakness, fatigue, palpitations, tremor, and blurred vision, as reported by the American Heart Association 4

Relationship with Other Conditions

• POTS is frequently associated with hypermobile Ehlers-Danlos syndrome (hEDS), with studies showing 25-37.5% of patients with hEDS/HSDs reporting a diagnosis of POTS, as noted by the American College of Medical Genetics 1, 2, 3