Understanding postural orthostatic tachycardia syndrome

We sat down with Shaun Ranada to speak about his research into postural orthostatic tachycardia syndrome (POTS) a debilitating condition that affects the body’s autonomic nervous system. Ranada is a primary care paramedic and a PhD student in the Cardiovascular and Respiratory Sciences program at the University of Calgary under the supervision of Drs. Satish Raj, MD, PhD, and Robert Sheldon, MD, PhD. His research is looking at the impact of carbon dioxide on this condition with the goal of finding treatments. 

What is POTS? 

Postural orthostatic tachycardia syndrome (POTS) is a condition that affects the body’s autonomic nervous system, which controls things like heart rate and blood pressure. POTS is diagnosed by a heart rate increase of 30 beats per minute or more while standing (or by 40 beats per minute for teens), without a drop in blood pressure. This increase in heart rate comes with symptoms—like chest pain, light-headedness, nausea, blurred vision, and mental clouding. This makes it hard for patients with POTS to tolerate standing, which severely limit their ability to participate in daily activities at school, work, or home. 

How common is POTS? 

POTS affects up to one per cent of the population, though the exact number of people with the condition is unclear. While anyone can develop POTS, it’s most common in young women. In fact, more than 85 per cent of those diagnosed are women of child-bearing age, and most people are between 15 and 25 years old when they find out they have it.

What causes POTS? 

The cause of POTS isn’t fully understood, and it likely results from multiple factors, which makes it challenging to diagnose and treat effectively. What we do know is the body’s automatic response to standing up is abnormal. When a healthy person stands up, gravity causes blood to move down to the lower parts of the body, like the legs and abdomen. To keep blood flowing to important organs like the heart and brain, the body automatically responds by tightening blood vessels and slightly increasing the heart rate. When POTS patients stand, this increase in heart rate is excessive and they experience a myriad of debilitating symptoms. 

How is it treated? 

There are no treatments specifically approved by the FDA or Health Canada for POTS. Instead, the condition is often managed with lifestyle changes and medications that, although they aren’t officially designed for POTS, may help. Since treatments don’t work the same for everyone, doctors create personalized plans for each patient, often combining different strategies. Non-medication approaches include regular aerobic exercise, wearing compression stockings and increasing salt and water intake. Medications commonly used to treat POTS include fludrocortisone, which helps the body hold on to fluids, beta-blockers to lower heart rate and vasoconstrictors to help squeeze blood vessels. 

Tell us about your research 

Some POTS patients experience something called postural hyperventilation, which can worsen symptoms and increase heart rate. Postural hyperventilation has three main factors: standing up, deeper breathing and low blood carbon dioxide (CO₂). When POTS patients stand, they start breathing more deeply, which causes them to exhale too much CO₂, leading to low levels of CO₂ in their blood. We are studying which of these factors contribute most to the increase in heart rate and symptoms in POTS patients, with the goal of identifying new treatments. We are also looking at whether breathing CO₂ reduces heart rate and symptoms in POTS patients, as a new treatment option.

Why is research in this area important? 

The lack of knowledge about and research into POTS has resulted in the under-representation of POTS in research funding, and poor and inadequate healthcare for patients. Patients with POTS are commonly misdiagnosed with anxiety or panic disorders and sent home from the clinic with no concrete answers or ways to improve their condition. As a result, many POTS patients feel unseen, and feel like they are living with an "invisible" illness. Research into POTS is crucial for raising awareness and improving outcomes for those affected. It will help doctors better understand this commonly overlooked condition, leading to quicker recognition, diagnosis and more effective treatments. Ultimately, research will help make this "invisible" disorder more visible.