What is happening in the body
The autonomic nervous system is the part of the nervous system you don’t think about. It runs in the background, keeping heart rate, blood pressure, breathing rate, digestion, and body temperature in the right range as the situations around you change. It has two arms that work in opposition:
- The sympathetic arm is the “go” pedal — it speeds the heart, narrows blood vessels, and prepares the body to move.
- The parasympathetic arm is the “rest and digest” pedal — it slows the heart and lets the gut do its work.
In dysautonomia, those two arms stop balancing each other properly. Heart rate and blood pressure no longer respond to standing, eating, or temperature changes the way they should. The heart itself is structurally normal — the problem is in how it’s being told to behave.
POTS specifically
Postural orthostatic tachycardia syndrome is the most common form of dysautonomia we see in adults under 50, and it disproportionately affects women. The defining feature is a heart rate that jumps when you stand up and stays elevated:
- In adults: a rise of at least 30 beats per minute within 10 minutes of standing.
- In adolescents (under 19): a rise of at least 40 beats per minute.
- Critically, blood pressure does not drop significantly. (If it does, we are dealing with orthostatic hypotension instead, which is a different problem.)
When you stand, gravity pulls roughly half a liter of blood downward into the legs and abdomen. A healthy nervous system tightens those vessels within seconds and the heart rate only nudges up. In POTS, the vessels don’t tighten well, and the heart compensates by racing — sometimes by 40, 60, even 80 bpm — to push enough blood up to the brain.
Common triggers and associations
POTS often appears after a clear inciting event:
- Post-viral. A flu-like illness, mononucleosis, or COVID-19 is a frequent trigger. Long-COVID-related POTS has become a large part of our practice.
- Autoimmune conditions. Some patients have antibodies that interfere with autonomic receptors.
- Hypermobile Ehlers-Danlos syndrome and other connective-tissue disorders. Stretchy blood vessels don’t constrict as effectively.
- Deconditioning after prolonged bed rest, surgery, or pregnancy.
- Mast cell activation, which often coexists with POTS and EDS.
Symptoms
POTS rarely shows up as just a fast heart rate. The fuller picture often includes:
- Brain fog and trouble concentrating
- Palpitations, especially on standing
- Lightheadedness, near-fainting, and sometimes true fainting
- Profound fatigue, often disproportionate to activity
- Exercise intolerance — feeling worse, not better, after workouts
- Gut symptoms: early fullness, nausea, bloating, constipation, or diarrhea
- Headaches, temperature dysregulation, and cold or mottled hands and feet
Related syndromes sit on a spectrum with POTS: orthostatic intolerance (similar symptoms without meeting the heart-rate criterion), neurocardiogenic (vasovagal) syncope (the classic faint with a clear drop in heart rate and blood pressure), and pure autonomic failure.
How we diagnose it
The diagnosis is clinical, supported by two simple tests:
- Active stand test. We measure heart rate and blood pressure lying flat, then again at 1, 3, 5, and 10 minutes standing. This is often enough to make the diagnosis.
- Tilt-table test. A motorized table tilts you to roughly 70 degrees while we monitor heart rate, blood pressure, and symptoms. This is especially useful when fainting is part of the picture.
We also rule out look-alikes — thyroid disease, anemia, dehydration, medication side effects, and the inappropriate sinus tachycardia and SVT we see in the EP clinic. An echocardiogram and basic labs are routine.
How we treat it
The treatment plan has layers, and we usually start at the bottom and add as needed.
Foundation (everyone)
- Salt and fluids. We aim for roughly 8–10 grams of salt and 2–3 liters of fluid daily, assuming no contraindication. This expands blood volume.
- Compression. Waist-high compression garments (20–30 mmHg) reduce venous pooling in the legs and abdomen.
- Graded recumbent exercise. Starting with recumbent bike, rowing machine, or swimming — anything that builds cardiovascular fitness without forcing the upright posture that triggers symptoms. We progress slowly over months. This is the single most evidence-based treatment.
- Avoid the triggers we can control: prolonged standing, heavy meals, hot showers, alcohol, and sudden position changes.
Medications (when needed)
- Beta-blockers (low-dose propranolol or metoprolol) blunt the heart-rate response.
- Ivabradine slows the sinus node without lowering blood pressure — particularly useful when blood pressure is already on the low side.
- Midodrine tightens blood vessels and raises standing blood pressure.
- Fludrocortisone helps the kidneys hold onto salt and water, expanding blood volume.
- We often combine these in low doses rather than push any single one to its maximum.
What to expect at your visit
We’ll go through your symptom timeline — when it started, what triggered it, what makes it better or worse. We’ll do an active stand in the office, review monitor data, and order a tilt-table if it adds useful information. Expect us to spend time on the non-drug pieces; they do the heavy lifting. Improvement usually comes in months, not days, but most of our POTS patients get substantially better with a consistent plan.