pathology: POTS (postural tachycardia syndrome)

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POTS (postural tachycardia syndrome)

Definition of

Dysautonomia (orthostatic circulatory dysregulation) that has been little researched to date, in which a change in position results in tachycardia, either by more than 30 bpm (40 in under 20-year-olds) or to more than 120 bpm (when standing) with barely reduced blood pressure (RRsyt max. minus 20 mmHg, RRdia max. minus 10 mmHg) during the first 10 min after standing up or in the tilt table test.
Several forms can be distinguished. In one form, two of the three orthostatic regulation mechanisms in the lower extremity fail: venous and arterial constriction, resulting in orthostatic hypovolemia. Venous pooling thus occurs with accumulation of blood in the low-pressure system through dilated veins, which reduces the preload of the heart and results in a reduced supply to the brain and an increase in the pulse rate: physiologically, the blood volume drops by 300 ml after 3 min and by 600 ml after 10 min during the transition to standing. With POTS, this volume is doubled. This triggers an increase in pulse rate via baroreceptors.
This may be caused by increased vascular permeability of the capillaries in the legs. While orthostasis regulation should physiologically be completed after 1-2 min, in POTS more and more volume is often lost through the capillaries to the interstitium.

In addition to the lack of response to adrenaline to stabilize blood volume through vasoconstriction in the lower extremity, in some cases there is also a hypoadrenergic situation. Part of this group shows centrally increased sympathetic activity (adrenergic form with increased sympathetic activity).

Also discussed is an inadequate response of baroreceptors in the carotid artery in an upright position with normal function in a flat position.

There also appears to be a neuropathic form with denervation of cardiac and sudomotor (sweat gland-controlling) sympathetic nerve fibers.

A smaller proportion of those affected also appear to suffer from general hypovolemia (hypovolemic form).

A striking anamnestic finding is that 50% had a viral infection before the first occurrence of POTS, and connections with previous vaccinations are also being discussed. Some of the affected patients have irritable bowel syndrome (irritable colon), which is usually associated with increased blood flow to the intestines and therefore reduces the available blood volume.

Finally, prolonged physical rest in the past can also lead to a reduced orthostasis regulation capacity due to a reduced cardiac output (here primarily: stroke volume). Prolonged bed rest is therefore a predisposing factor.

Studies show a 20% compared to physiological 10% increased drop in brain supply in POTS, corresponding to 10 mmHg compared to physiological 4 mmHg, which correlates directly with hyperventilation and hypocapnia. Anxiety or panic intensify this effect.

It mainly affects younger people (peak age 15-50) who are otherwise organically healthy, but who often suffer from one or more functional disorders such as migraines, irritable bowel syndrome, irritable bladder syndrome, pain disorders, fatigue syndromes, sleep disorders, nausea, dizziness, feeling wrapped up in absorbent cotton. There is a clear overlap with CFS.

Women are more frequently affected than men (5:1). The symptoms often begin before the age of 18 and are often progressive
In Germany, a prevalence of 0.1 – 1% is assumed, in the USA 1-3 million people are affected.

The prognosis is rather favorable, multimodal, behavioral therapy and, to a lesser extent, medication measures usually lead to a significant improvement, in 50% within 1-3 years even untreated to spontaneous improvement.

Cause

  1. Autoimmunological processes following viral or bacterial infections, including Covid-19
  2. Vaccinations
  3. Traumas
  4. Stress
  5. Past or ongoing stressful phases of life

Predisposing

  1. Fibromyalgia
  2. Ehlers-Danlos syndrome (approx. 80% show POTS)
  3. Hypovolemia (renal function ? impaired RAAS ?)
  4. Sensitive-anxious disposition
  5. Prolonged bed rest

Diagnosis

  1. Tilt table test (head-up tilt test) with continuous non-invasive hemodynamic monitoring
  2. Schellong test 1 (standing after lying down) and 2 (moderate exertion such as climbing stairs after lying down)

Symptoms

  1. Dizziness
  2. possibly syncope
  3. Tiredness
  4. Drowsiness
  5. Headache
  6. Concentration disorders,
  7. Hyperhidrosis
  8. Trembling
  9. Visual disturbances
  10. Dyspnea, tachypnea
  11. Heat intolerance
  12. Chest pain
  13. Feeling of weak legs
  14. Stress intolerance, reduced resilience
  15. Fear, panic
  16. Possibly barely controllable exhaustion after the onset of symptoms
  17. Sleep disorders (in 40%) due to nocturnal tachycardia, daytime sleepiness, disturbed sleep structure
  18. Tendency to hyperventilation with consecutive hypocapnia and cerebral hypoperfusion

Complications

  1. Reduction in earning capacity (in 25%)
  2. Depression
  3. Risks of syncope
  4. Bedriddenness

DD

  • orthostatic hypotension

Therapy

  1. Improvement within 5 years in 50%, but 81% are not fully recovered. A multimodal therapy is required in any case.
  2. Behavioral adaptations: Slow down changes in position by raising the upper body, avoid standing for long periods of time
  3. Reduce risk factors: Obesity, rest and inactivity, hyperventilation, diuretics, Ca-channel blockers, mineralocorticoid antagonists, beta-blockers (are not always a risk factor)
  4. Adequate fluid (at least 2 l / d) and salt intake (at least 10-12 g / d) or NaCl infusions.
  5. Generally sufficient exercise and physical training, especially endurance training (!) and strength training are important measures, even if they are uncomfortable in an upright position! Initially, only recumbent forms of exercise can be practiced: Swimming, recumbent bike, all forms of strength training while lying down. There are special treadmills with a compression range up to the hips or chest.
  6. Sleep discipline (including: no alcohol before going to bed, no caffeine 6-8 hours before, nap no longer than 30 minutes, do not stay in bed for too long after waking up)
  7. Compression stockings and other compression measures, including tone-enhancing training of the abdominal muscles
  8. Avoid overheating and saunas
  9. Alcohol cessation
  10. Avoid larger, heavier meals
  11. Discontinue all medication that promotes dysregulation, such as diuretics, in consultation with the attending physician
  12. Respiratory intervention: if there are signs of POTS symptoms, increased diaphragmatic breathing helps, as this transports more blood cranially. Breathing technique to avoid hyperventilation and hypocapnia.
  13. Cryotherapy (pronounced, but also moderate), especially of the legs, from Kneipp and shorts at low temperatures to the cold chamber.
  14. Pharmacological: there is no single approved drug against POTS. Therefore, all attempts are experimental and often unsuccessful with: Mineralocorticoids, a1-agonists, beta-blockers, melatonin, acetylcholinesterase inhibitors, anti-allergics, immunoglobulins, possibly serotonin reuptake inhibitors (for more pronounced anxiety) and a few others
  15. Psychotherapy to alleviate anxiety, panic and depression that exacerbate POTS symptoms.
  16. Symptomatic therapy of comorbidities with interaction with POTS.