Mechanisms involved
This condition is explained through the mechanisms below. Each one is taught as ordinary physiology first.
Primary
Secondary / contributing
Immune cells involvedWho is actually in the tissue
A meaningful share of POTS looks immune-driven rather than purely mechanical.
Selected cell
B cell and antibodies
Produces antibodies. Some are useful, some are autoantibodies against autonomic receptors — one of the leading explanations for post-viral dysautonomia.
Autoantibodies against adrenergic and muscarinic receptors are found in a subset, offering a mechanism for the sudden post-infectious onset.
Schematic drawings, not micrographs. Immune findings here describe mechanism and association; none of them are diagnostic tests.
What it is
Postural orthostatic tachycardia syndrome is a sustained heart-rate rise of at least 30 bpm (40 in adolescents) within ten minutes of standing, without a large fall in blood pressure, with symptoms for at least three months. Dysautonomia is the broader umbrella of autonomic dysfunction, of which POTS is one form.
How the mechanisms produce this
- Where venous return is reduced — by compliant veins, low blood volume, or deconditioning — the reflex meets its target using heart rate alone.
- Described subtypes (hyperadrenergic, neuropathic, hypovolemic) point at different limiting factors and different first-line treatments.
- Mast-cell mediators dilate vessels and raise heart rate directly, so immune reactivity can be the limiting factor rather than tissue.
- Post-viral small-fiber injury is now the best-documented route into the neuropathic pattern.
What tends to help
- Fluids, salt and waist-high compression as the foundation, before medication.
- Recumbent-to-upright reconditioning, dosed against symptoms — and paused entirely if post-exertional malaise is present.
- Medication chosen by limiting factor: volume, rate, vessel tone, or sympathetic drive.
- Review current medications for classes that worsen the picture.
Where the evidence is thin
The randomized evidence base is thin; most of the strong evidence supports lifestyle and exercise rather than any specific drug.