Dysautonomia is a condition where the autonomic nervous system is dysfunctional. In other words, automatic mechanisms are not working properly — think blood pressure, heart rate, body temperature, digestion of food, etc. Postural orthostatic tachycardia syndrome (POTS) is one type of dysautonomia.1
POTS can be triggered by multiple conditions, including hormonal changes, infections, emotional or physical trauma, connective tissue and autoimmune diseases. There can be a significant overlap with patients who have migraines, anxiety disorders and depression as well.2,3,4
Because specific biomarkers can be difficult to identify, these conditions are often underdiagnosed. One Chinese study estimated a prevalence of 6.8% in the pediatric and adolescent population, and while some studies have indicated no gender differences, others have demonstrated a higher prevalence in females with a ratio of up to 4:1.5,6 Nonetheless, some biomarkers have been identified, including decreased 24-hour urine sodium excretion, low plasma renin activity7 and elevated plasma norepinephrine levels when standing.8
In pediatrics, POTS is defined by excluding other disorders (arrhythmias, thyroid disease, anemia, etc.), six months of symptoms and a sustained heart rate increase of more than 40 points when changing from a laying to standing position (should have at least three to five minutes of standing before taking standing blood pressure) without a significant reduction in blood pressure.
The medical community is learning more about POTS, and it is becoming increasingly recognized, diagnosed and treated. Unfortunately, there is not a specific curative treatment that has been identified, thus management focuses on symptom control, as well as identifying and treating the underlying triggers as the mainstays of therapy.1
Typically, when an individual stands up, gravity pulls blood to the lower extremities and the autonomic nervous system will utilize signaling from decreased vessel wall tension and arterial baroreceptors to increase sympathetic and decreased parasympathetic responses. This results in vasoconstriction, increased heart rate and increased cardiac output to improve circulation.
This is aided by the renin-angiotensin-aldosterone system (RAAS), which increases absorption of water and sodium, as well as activating muscles in the lower extremities to compress and push blood flow superiorly. Finally, small veins help reduce the amount of blood pooling that can occur and continue forcing blood upward.
In dysautonomia, the above mechanisms used by the body to maintain cardiac output do not respond appropriately. This causes reduced venous return and therefore decreased cardiac output, leading to excessive tachycardia, hypotension and, potentially, syncope.1
The resultant decrease in cardiac output has a number of physiologic effects that result in the signs and symptoms observed in POTS patients. Patients often will experience dizziness, fainting, chest discomfort, shortness of breath, brain fog, headaches, nausea, weakness, acrocyanosis and tunnel vision. These symptoms are often exacerbated when changing from a lying to standing position. Other non-orthostatic symptoms can include generalized gastrointestinal discomfort and bladder symptoms.
Due to the broad range of symptoms, treatment strategies are often collaborative and multidisciplinary. Non-pharmacologic treatments are typically the first line. Initially, this should include avoidance of triggers, including long periods of standing upright, rapid changes in position and excessive heat. Increasing blood volume is also a mainstay and is accomplished by increasing fluid and electrolyte intake, as well as compression stockings.
Exercises, especially those tailored to patients with dysautonomia, can be employed and have been shown to improve symptoms and quality of life.1 A few particular protocols have been created to help formalize POTS specific exercises.9
Oftentimes, pharmacologic treatments are also required to help minimize symptoms if the above changes are deemed inadequate. These include oral rehydration tablets (salt pills) and oral iron therapy (if patients are iron deficient). Prescription medications can also be utilized, such as midodrine (an alpha-1 agonist) to constrict blood vessels, improving blood pressure and decreasing tachycardia.
Beta blockers can also be employed — especially to target symptoms of tachycardia that in some studies have shown to be more effective than midodrine for symptom relief.10 Finally, fludrocortisone has been suggested to improve sodium retention and increase plasma volume, though it has not been well verified in clinical studies.1
Because of the complexity of symptoms and comorbidities along with a broad range of treatments, pediatric cardiologists are often employed along with neurologists, physical therapists, mental health specialists and others to help manage this complicated condition.
Patients in Georgia can access crucial care for autonomic disorders close to home. For the treatment of autonomic disorders in children, Wellstar pediatric cardiologists see patients in six metro Atlanta offices. Call (470) 956-9171 to make an appointment with Dr. Jeffrey Sacks or one of his colleagues.
Dr. Jeffery Sacks
Dr. Sacks is a pediatric cardiologist with Wellstar Center for Cardiovascular Care. He received his medical degree from and completed his pediatric residency at Emory University School of Medicine in Atlanta. Dr. Sacks completed his pediatric cardiology fellowship at the Sibley Heart Center, now Children’s Healthcare of Atlanta Cardiology. Dr. Sacks is board certified as a pediatric cardiologist and is a member of the American Academy of Pediatrics and the American College of Cardiology.
References
1 Goldstein DS, Holmes C, Frank SM, Dendi R, Cannon RO 3rd, Sharabi Y, Esler MD, Eisenhofer G. Cardiac sympathetic dysautonomia in chronic orthostatic intolerance syndromes. Circulation. 2002 Oct 29;106(18):2358-65. doi: 10.1161/01.cir.0000036015.54619.b6. PMID: 12403667.
2 Chen G, Du J, Jin H, Huang Y. Postural Tachycardia Syndrome in Children and Adolescents: Pathophysiology and Clinical Management. Front Pediatr. 2020 Aug 20;8:474. doi: 10.3389/fped.2020.00474. PMID: 32974246; PMCID: PMC7468430.
3 Olshansky B, Cannom D, Fedorowski A, Stewart J, Gibbons C, Sutton R, Shen WK, Muldowney J, Chung TH, Feigofsky S, Nayak H, Calkins H, Benditt DG. Postural Orthostatic Tachycardia Syndrome (POTS): A critical assessment. Prog Cardiovasc Dis. 2020 May-Jun;63(3):263-270. doi: 10.1016/j.pcad.2020.03.010. Epub 2020 Mar 25. PMID: 32222376; PMCID: PMC9012474.
4 Bryarly M, Phillips LT, Fu Q, Vernino S, Levine BD. Postural Orthostatic Tachycardia Syndrome: JACC Focus Seminar. J Am Coll Cardiol. 2019 Mar 19;73(10):1207-1228. doi: 10.1016/j.jacc.2018.11.059. PMID: 30871704.
5Lin J, Han Z, Li X, Ochs T, Zhao J, Zhang X, et al.. Risk factors for postural tachycardia syndrome in children and adolescents. PLoS ONE. (2014) 9:e113625. 10.1371/journal.pone.0113625
6 Boris JR. Postural orthostatic tachycardia syndrome in children and adolescents. Auton Neurosci. 2018 Dec;215:97-101. doi: 10.1016/j.autneu.2018.05.004. Epub 2018 May 12. PMID: 29778304
7 Raj SR, Biaggioni I, Yamhure PC, Black BK, Paranjape SY, Byrne DW, Robertson D. Renin-aldosterone paradox and perturbed blood volume regulation underlying postural tachycardia syndrome. Circulation. 2005 Apr 5;111(13):1574-82. doi: 10.1161/01.CIR.0000160356.97313.5D. Epub 2005 Mar 21. PMID: 15781744.
8 Shannon JR, Flattem NL, Jordan J, Jacob G, Black BK, Biaggioni I, Blakely RD, Robertson D. Orthostatic intolerance and tachycardia associated with norepinephrine-transporter deficiency. N Engl J Med. 2000 Feb 24;342(8):541-9. doi: 10.1056/NEJM200002243420803. PMID: 10684912.
9 Fu Q, Levine BD. Exercise and non-pharmacological treatment of POTS. Auton Neurosci. 2018 Dec;215:20-27. doi: 10.1016/j.autneu.2018.07.001. Epub 2018 Jul 4. PMID: 30001836; PMCID: PMC6289756.
10 Lai CC, Fischer PR, Brands CK, Fisher JL, Porter CB, Driscoll SW, Graner KK. Outcomes in adolescents with postural orthostatic tachycardia syndrome treated with midodrine and beta-blockers. Pacing Clin Electrophysiol. 2009 Feb;32(2):234-8. doi: 10.1111/j.1540-8159.2008.02207.x. PMID: 19170913.
