Postural tachycardia syndrome (PoTS) is an abnormal increase in heart rate that occurs after sitting up or standing. It typically causes dizziness, fainting and other symptoms.
It’s sometimes known as postural orthostatic tachycardia syndrome.
PoTS affects many different people, but is most common in girls and women aged 15 to 50.
Some people have mild symptoms, while others find the condition affects their quality of life. PoTS often improves gradually over time, and there are a number of self-care measures and medications that can help.
What happens in PoTS
Normally when you sit up or stand, gravity pulls some of your blood down to your belly area, hands and feet. In response, your blood vessels quickly narrow and your heart rate increases slightly to maintain blood flow to the heart and brain, and prevent blood pressure dropping.
This is all done without needing to think about it by the autonomic nervous system – the nervous system in charge of automatic body functions.
In PoTS, the autonomic nervous system doesn’t work properly. There’s a drop in blood supply to the heart and brain when you become upright and the heart races to compensate for this.
Symptoms of PoTS
You can develop PoTS suddenly, or it can come on gradually over time.
It causes a range of symptoms that occur within a few minutes of sitting up or standing. Lying down may relieve some of the symptoms.
Typical symptoms of PoTS include:
- dizziness or light-headedness
- heart palpitations
- shaking and sweating
- weakness and fatigue
- poor sleep
- chest pain
- feeling sick
- shortness of breath
Some people notice that things such as feeling hot, eating, strenuous exercise and being on their period make their symptoms worse.
The symptoms can have a number of causes, such as medication or low blood pressure, so it’s a good idea to seek a proper diagnosis. Sometimes it can be misdiagnosed as anxiety or panic attacks.
Tests for PoTS
A diagnosis of PoTS is made if your heart rate increases by 30 beats per minute (bpm) or more (40bpm in those aged 12-19) after 10 minutes of standing, or if it increases to more than 120bpm.
You may have a range of tests to confirm a diagnosis and rule out other conditions, including:
- the tilt table test – your heart rate and blood pressure are measured while lying on a bed, and the bed is then tilted into a more upright position while further measurements are taken
- the active stand test – your heart rate and blood pressure are measured after lying down, immediately upon standing, and after 2, 5 and 10 minutes
- an electrocardiogram (ECG) – a test of your heart’s electrical activity
- an echocardiogram – an ultrasound scan of your heart
- 24-hour ambulatory blood pressure and heart rate monitoring – small devices attached to your belt take regular readings while you’re doing normal activities
- blood tests – to test your kidney, liver and thyroid function, and measure blood count and your calcium and glucose levels
Treatments for PoTS
Self-care measures can sometimes help reduce the symptoms of PoTS. If these don’t work, you may need to take medication.
There’s currently no medication licensed for the treatment of PoTS, but your specialist might suggest trying a medication “off label”, such as:
- a beta-blocker or ivabradine – which decreases the heart rate
- midodrine – which narrows the blood vessels
- fludrocortisone – which decreases the amount of sodium lost in your urine
- selective serotonin reuptake inhibitors (SSRIs) – a type of antidepressant that can affect how your nervous system works
If a medicine is used “off label”, it means it hasn’t undergone clinical trials for this use, but many experts believe it’s likely to be effective and your doctor will discuss the possible benefits and risks with you.
Causes of PoTS
In many cases, the cause of the problem with the nervous system in people with PoTS is unknown.
Teenagers will sometimes develop PoTS and find it gradually disappears a few years later. Sometimes it can develop suddenly after a viral illness or traumatic event, or during or after pregnancy.
Some of the other known causes are:
- joint hypermobility syndrome – a condition (often inherited) that results in unusually flexible joints and abnormally elastic blood vessels
- other underlying conditions – such as diabetes, amyloidosis, sarcoidosis, lupus, Sjogren’s syndrome or cancer
- poisoning – with alcohol or certain metals
- inheriting a faulty gene that causes too much of the “fight or flight” hormone noradrenaline to be produced
PoTS also occurs quite commonly alongside chronic fatigue syndrome (CFS).