Clinical Features and Symptoms of Postural Tachycardia Syndrome

Case study

This article presents the case of a woman who was working as an aviation diesel mechanic with the U.S. Navy.¹ She developed back and abdominal pain in October 2015, which progressively worsened, causing her to fall sick and faint up to 10 times a day, despite multiple hospital visits.¹

In 2022, she was diagnosed with a rare nervous system disorder known as postural tachycardia syndrome (PoTS), which affects the flow of blood when in an upright position.¹ This led her to experience an elevated heart rate, light-headedness, and repeated episodes of fainting.¹ With no available cure, she was confined to her house and dependent on medication to reduce her bouts of fainting. She also required external help to assist her with most day-to-day functions.¹

In 2022, she was diagnosed with a rare nervous system disorder known as postural tachycardia syndrome (PoTS), which affects the flow of blood when in an upright position.¹ This led her to experience an elevated heart rate, light-headedness, and repeated episodes of fainting.¹ With no available cure, she was confined to her house and dependent on medication to reduce her bouts of fainting. She also required external help to assist her with most day-to-day functions.¹

Background

Postural tachycardia syndrome (PoTS) is a chronic disorder of the autonomic nervous system which affects multiple organ systems.² It is characterized by a sudden spike in the heart rate and drastic drops in blood pressure on maintaining an upright body position, with a rapid return to normalcy in a supine position.² It is an uncommon condition affecting only 0.2% of the general population, with an estimated 500,000-1,000,000 cases recorded in the United States. Its incidence is much higher among females, and mostly affects the age groups of 15-25 years^.2,3

Clinical presentation and symptoms

PoTS presents in three different forms with diverse pathologic mechanisms:

1. Neuropathic PoTS: It is the most common form of PoTS, accounting for 50% of the diagnosed population.² It involves a dysfunction of the postganglionic sudomotor fibers of the feet along with denervation, leading to disruption of signals in the lower limbs.² This affects the process of venoconstriction during an upright posture, allowing excessive pooling of blood in lower limb vessels.²
2. Hypovolemic PoTS: Patients with this form of PoTs present with low blood volume and have very low levels of plasma renin and aldosterone.² In comparison with the healthy population, these patients exhibit dysregulated levels of angiotensin enzymes, leading to abnormal blood pressure levels.²
3. Hyperadrenergic PoTS: This form of PoTS is characterized by high levels of plasma norepinephrine levels leading to a sharp rise in systolic blood pressure at an upright position.²

While an abnormal blood flow and vascular pressure are commonly observed, patients with PoTS experience a range of other symptoms such as fatigue, headache, chest pain, and cognitive impairment.³ Interestingly, the dysregulation of the autonomic nervous system has a wide-ranging effect on other organs.³

Since gastrointestinal (GI) activity is strongly influenced by autonomic nervous regulation, many patients with PoTS also report GI symptoms which range from mild dysmotility to complete intestinal failure, requiring total parenteral nutrition or surgery.³

Diagnosis and treatment

A diagnosis of PoTS requires a thorough patient evaluation across multiple parameters³ as follows:

1. Evaluation of the patient’s medical history to determine the triggers, time of onset, severity, and physical manifestations.³
2. Comprehensive cardiac and neurologic examinations, such as the Holter’s test, exercise stress test, blood and thyroid tests, and electrocardiography (ECG).³
3. A head-up tilt test with non-invasive beat-to-beat hemodynamic monitoring.³

Since PoTS has several manifestations with different mechanistic approaches, a single broad treatment strategy is not effective for all patients.³ A combination of both nonpharmacologic and pharmacologic interventions is found to be effective against the symptoms of PoTS, including:

1. A structured exercise program for patients with POTS.³
2. Increasing salt concentrations and fluid intake to increase blood volume.³
3. Reducing pooling of venous blood at an upright position by using compression garments.³
4. A variety of medications such as β-blockers, midodrine, fludrocortisones, central sympatholytic agents, pyridostigmine, ivabradine, octreotide, and erythropoietin.³

The use of drugs that block the norepinephrine reuptake transporter should be avoided, since they are known to exacerbate the symptoms of PoTS.³

Educating patients about this condition helps them avoid potential triggers and ensure better management of their symptoms.³

Conclusion

Postural tachycardia syndrome (PoTS) represents a rare condition of the autonomic nervous system which critically effects the homeostasis of the cardiovascular system, limiting the patient’s functioning drastically. While a cure for this condition does not exist currently, a combination of pharmacologic drugs, diet, and exercise can greatly improve the patient’s quality of life.

References 

1. Woman ‘allergic to gravity’ can only stand for three minutes at a time without getting sick or fainting | National Post. (2022). Retrieved 12 September 2022, from https://nationalpost.com/news/world/woman-allergic-to-gravity-can-only-stand-up-three-minutes-at-a-time-without-fainting
2. Safavi-Naeini, P., & Razavi, M. (2020). Postural Orthostatic Tachycardia Syndrome. Texas Heart Institute journal, 47(1):57–59.
3. Vernino, S., Bourne, K., Stiles, L., Grubb, B., Fedorowski, A., & Stewart, J. et al. (2021). Postural orthostatic tachycardia syndrome (POTS): State of the science and clinical care from a 2019 National Institutes of Health Expert Consensus Meeting – Part 1. Autonomic Neuroscience, 235:102828.