Postural Tachycardia Syndrome (PoTS)
Overview
When to see a cardiologist
Symptoms of PoTS
Causes of PoTS
Complications of PoTS
Overview of PoTS
Postural tachycardia syndrome (PoTS) is a condition where the heart rate increases when someone goes from sitting or lying down to standing up. The main symptom is feeling a fast heartbeat (palpitations) when standing, which only goes away when sitting or lying down again. Symptoms usually start in early adolescence or between the ages of 30 and 50. In adolescents, this condition affects girls more than boys, around 70% versus 30%. In adults, it almost exclusively affects women.
To diagnose PoTS, doctors use either an active stand test or a head-up tilt test. During the active stand test, the patient's blood pressure and pulse are measured while lying down, and then again while standing up over a period of 5 minutes. If the heart rate significantly increases without a big drop in blood pressure, it confirms a diagnosis of PoTS. The head-up tilt test involves a similar change in position, but the patient is strapped to a table that tilts from lying down to a near-vertical position. The same measurements are taken during this test. Both tests can be used for diagnosing PoTS.
When considering a diagnosis of PoTS, it's important to rule out other medical conditions that can cause similar symptoms and may require different treatments. Many of the tests that a person with possible PoTS may undergo will be focused on ruling out other problems.
When to See a Cardiologist
Many different sorts of doctor can specialise in seeing patients with PoTS, including cardiologists, neurologists, rheumatologists, paediatricians and primary care physicians (GPs).
Cardiologists can be particularly helpful to differentiate between PoTS and other causes of palpitation symptoms including abnormal heart rhythms (arrhythmias) such as supraventricular tachycardias, atrial tachycardias and atrial fibrillation. Some patients with PoTS also have symptoms in common with fainting disorders, so it can be useful to see a cardiologist to rule out conditions such as orthostatic hypotension and reflex (vasovagal) syncope, which can cause lightheadedness and loss of consciousness, similar to severe cases of PoTS.
Symptoms of PoTS
The core symptom of PoTS is experiencing palpitations when standing up, accompanied by dizziness, lightheadedness or fatigue. The symptoms are not present when lying down. It is normal to experience a transient rise in heart rate on first standing up, but if the heart rate stays high and causes other associated symptoms, this is suggestive of PoTS. The symptoms should have been present for three months or more to diagnose PoTS.
Causes of PoTS
A wide variety of mechanisms can contribute to PoTS, and more than one mechanism may be present in an individual patient. Common problems found in patients with PoTS include dehydration, failure of heart rate and blood pressure control (“autonomic dysregulation”), overstimulation of adrenergic signalling and, in some patients, autoimmune diseases.
Some other conditions are known to commonly coexist with, but not necessarily cause PoTS. Examples of conditions commonly found alongside PoTS include Ehlers Danlos Syndrome type III (hypermobility type), mast cell activation syndrome and postural hypotension.
Complications of PoTS
The main complication of PoTS is an inability to stand, which can lead to poor mobility and all the complications that flow from this. Patients with PoTS may find it difficult to live an active life, which can lead to other medical problems.