Postural tachycardia syndrome

What is POTS?

The autonomic nervous system controls, without us thinking about it, heart rate, blood pressure, digestion and temperature. When it does not work properly, this is called dysautonomia.

Postural orthostatic tachycardia syndrome (POTS, Postural Orthostatic Tachycardia Syndrome, sometimes called STOP in French) is a form of dysautonomia: when moving from lying down to standing, the heart speeds up excessively and symptoms appear, which improve when lying down again.

It more often affects women, usually between 15 and 50, and sometimes appears after a viral infection, a pregnancy, surgery or a period of bed rest. Cases have also been described after COVID-19, as part of long COVID.

Measuring the heart lying down, then standing

According to international criteria, POTS is diagnosed when:

1. heart rate rises by at least 30 beats per minute (40 in 12- to 19-year-olds) within 10 minutes of standing up;
2. without a significant drop in blood pressure (which distinguishes POTS from orthostatic hypotension);
3. with symptoms for at least 3 months that get worse when standing and improve when lying down.

The doctor carries out an active stand test (measurements lying down then standing) or a tilt-table test in hospital. They also look for other possible causes: dehydration, anaemia, thyroid problems, medication side effects, heart disease.

Hypermobile EDS and dysautonomia

POTS and other forms of dysautonomia are often reported in people with hypermobile EDS or a hypermobility spectrum disorder. Several studies find they are more common in these situations.

The reasons are still being studied: greater flexibility of the blood vessels, which would let blood pool in the legs, is one of the explanations suggested. POTS can also coexist with digestive problems or mast cell activation.