Definition and Overview
Long COVID (post-COVID condition) refers to symptoms that persist for more than 12 weeks after SARS-CoV-2 infection and are not explained by other causes. Approximately 10-30% of COVID-19 infected people experience long Covid, affecting tens of millions of people worldwide.
Autonomic dysfunction is one of the most common symptoms of Long Covid and includes orthostatic intolerance, tachycardia, fatigue, cognitive impairment (brain fog), and digestive symptoms. The American Autonomic Society has released an official statement on Long Covid POTS in 2021.
Epidemiology
prevalence rate
POTS or orthostatic intolerance is found in approximately 30-60% of Long Covid patients. In a study based on the standing tilt test, abnormal findings were reported in approximately 67% of Long Covid patients.
risk factors
- Women (approximately 2 to 4 times more common than men)
- 25-50 years old age group
- History of autonomic symptoms before COVID-19 infection
- Underlying diseases such as EDS, MCAS, etc.
pathophysiology
proposed mechanism
The exact mechanism of Long Covid autonomic dysfunction has not yet been fully elucidated, but several mechanisms have been proposed.
- Autoimmune mechanism: SARS-CoV-2 infection disrupts autonomic function by inducing autoantibodies against autonomic receptors (adrenergic receptors, muscarinic receptors).
- Vagus nerve dysfunction: Damage to the vagus nerve due to direct nerve invasion by the virus or inflammation.
- Microvascular damage: Microcirculation disorder and vascular dysregulation due to endothelial cell damage
- Deconditioning: Decreased cardiovascular adaptation due to reduced activity during infection.
- Persistent inflammation: Chronic low-intensity inflammation due to residual viral antigen or reactivation.
- Mast cell activation: Mast cell instability triggered by infection.
symptoms
Cardiovascular autonomic symptoms
- Tachycardia, palpitations when standing up
- Orthostatic dizziness, presyncope
- exercise intolerance
- Chest pain, chest tightness
systemic symptoms
- Extreme fatigue (including post-exertional malaise, PEM)
- Cognitive impairment (brain fog): difficulty concentrating, memory loss, difficulty finding words.
- sleep disorder
- headache
digestive symptoms
- Abdominal pain, bloating, nausea
- diarrhea or constipation
- loss of appetite
Other
- Temperature regulation disorder
- abnormal sweating
- Sensitivity to light and sound
diagnosis
standing evaluation
- Active standing test: Heart rate increase of 30 bpm or more within 10 minutes of standing (POTS standard)
- Head-up tilt test: more accurate evaluation
autonomic nerve test battery
- HRV analysis, Valsalva maneuver, deep breathing heart rate variability, QSART
Differential diagnosis
- Exclude medical causes that cause orthostatic intolerance, such as anemia, thyroid dysfunction, and adrenal insufficiency.
- Check for presence of autonomic dysfunction before infection
treatment
Non-drug treatment (1st line)
- Fluid and salt intake: 2-3 L of water per day, 10-12 g of salt.
- Compression clothing: abdominal compression band, thigh-high compression stockings (30-40 mmHg)
- Progressive exercise program: Initially begins with recumbent exercise and gradually transitions to standing exercise. A variant of the Levine protocol (CHOP protocol) is utilized.
- Sleep hygiene, stress management
medication
If non-drug treatment is not sufficiently controlled, add it step by step.
- Ivabradine: Selective inhibition of sinoatrial node, tachycardia control
- Midodrine: α1 agonist, relieves orthostatic symptoms by constricting blood vessels
- Fludrocortisone: mineralocorticoid, securing intravascular volume
- Propranolol: Controls tachycardia in low doses (10-20 mg).
- Pyridostigmine: Inhibits acetylcholinesterase, enhances autonomic nerve transmission
Cognitive Impairment (Brain Fog) Management
- Cognitive pacing: Balancing activity and rest
- Use memory aids
- Getting adequate sleep
- Improvement of cerebral blood flow through exercise
Progress and prognosis
The natural history of Long Covid autonomic dysfunction varies greatly from person to person. Many patients show gradual improvement over 6 to 18 months, but in some cases, symptoms persist for more than 2 years. Starting appropriate non-pharmacological treatment early and maintaining a progressive exercise program are the most important factors in promoting recovery.
Since reinfection can worsen autonomic dysfunction, infection prevention (vaccination, hygiene rules) is also part of management.