Postural orthostatic tachycardia syndrome (POTS) is defined as orthostatic intolerance on standing with increase in HR by at least 30 bpm without postural hypotension.

There are 3 major pathophysiological mechanisms – Neuropathic which is seen in >50% of the patients; hyperadrenergic with increase in norepinephrine seen in 30% of the patients; and hypovolumic. Other rare mechanisms are autoimmune, genetic and deconditioning. It affects predominantly the young premenopausal women.

Recently, it has been found to be linked with COVID, particularly the long haul post-COVID symptoms are related with POTS, which was wrongly interpreted as psychogenic or post-COVID syndrome. Basic mechanisms are autoimmune response due to virus and autonomic neuropathy due to antibodies.

Major symptoms are light-headedness, breathlessness, palpitation, chest pain, fainting, presyncope and syncope.

Investigations are routine blood biochemistry, ECG, Holter, Echo, head-up tilt test (HUT), test for autonomic dysfunction, test for neuropathy.

Major treatment is nonpharmacological, 2-3 L of fluid/day, 10 g of salt. Recumbent exercise, compression stockings, avoiding stress, avoiding alcohol, saturated fats and heavy meals are advised.

Pharmacological treatment comprises of vasoconstrictors like midodrine, fludrocortisone, beta blockers, ivabradine, pyridostigmine, erythropoietin, IVIG. But no drugs are US FDA approved.