POTS Explained

What is POTS and How is it diagnosed?

POTS or Postural Orthostatic Tachycardia Syndrome is a relatively simple diagnosis made on interval lying then standing (can be done with a small lean against the wall) heart rate measurements typically at 1 minute intervals out to 10 minutes usually combined with blood pressure readings. A rise in heart rate by more than 30 bpm at any time of this period meets the diagnosis. But there is a lot more to POTS than is typically understood.
POTS can be purely a heart rate rise but it can also occur with concurrent postural hypotension with a blood pressure drop of more than 20mmHg,

Looking for the presence of both features can alter management.

What are the Symptoms of POTS?

POTS is typically described as orthostatic (post standing) dizziness, racing heart (palpitations), as it progresses leads to exertional fatigue and brain fog. Depending on the associated conditions it can be combined with post exercise fatigue, bladder hypersensitivity/incontinence, poor sleep, generalised aches, leg swelling, occasional purple feet, intermittent body swelling, itch, rash.

What Can trigger POTS?

POTS can develop as a result of many different triggers but typically can occur in post viral illness, commonly seen in long Covid, even post many vaccinations and can present with Chronic Fatigue Syndrome (CFS) which has an overlap to a condition called Myalgic Encephalomyelitis (ME) and Fibromyalgia. It can be seen in connection to connective tissue disorders like Ehlers-Danlos with Hypermobility Disorders (HSD). There is overlap with Immunological conditions including Mast Cell Activation Syndrome (MCAS), Lupus, Hashimoto’s thyroiditis and Sjogren’s. It can occur in chronic gastroenterology or gynaecological conditions including endometriosis and can even be triggered post concussion. There is also some overlap seen in eating disorders especially with low BMI, also in some patients with ADHD, anxiety and depressive conditions partly from the conditions and partly from their treatment.

Why does POTS occur?

This is the more technical aspect of the condition and it does vary depending on the underlying associated condition. There are two main aspects of POTS involving nerve function and blood return.

The breakdown of the normal autonomic function (dysautonomia), can be from excessive sympathetic activation (hyperadrenergic) similar to taking excess caffeine or adrenaline with rapid heart rate rises or when the nerves developed impaired function (neuropathic POTS) leading to reduced muscular and vascular function.

Certain conditions can directly lead to poor venous blood return from inadequate leg muscle tone or vascular abnormalities. Leg muscle contraction is key to force blood back to the heart within the passive venous system.

There is evolving understanding that certain auto-antibodies maybe implicated in trigger the develop of POTS.

Why does POTS fluctuate in severity?

POTS isn’t a binary condition and you don’t feel normal with a rise of 29bpm and unwell at 30bpm. It is used as a cut-off but isn’t actually that helpful when it comes to management. POTS often gets worse when deconditioning progresses ie your cardiac fitness, muscle tone falls the symptoms worsen and it becomes even harder to function and it begins to spiral and worsen further.

How is POTS managed?

There are several key aspects to managing most POTS patients and a few factors that differ depending on the underlying aetiology and associated conditions.

Lifestyle and Aids:

1. Improve vascular hydration- typically encourage fluid intake to 2.5-3L/day and combine with various salts and electrolytes to retain the fluid within the blood stream. The use of electrolyte supplements, Powerade, Gatorade, Gastrolyte can be beneficial.

2. Improve leg and core muscle bulk and tone, this reduces the pooling and improves blood return to the heart. This is best achieved with floor and recumbent exercises to reduce symptoms, consider reformer pilates and exercise bikes.

3. Compression stockings with 20-30mmHg of compression that cover the entire legs are associated with both improved postural blood pressure and heart rate changes.

4. Pre standing muscle recruitment. A study looked at 2 techniques one called PREACT and one called TENSE showed an improvement in standing blood pressure by 4 and 5mmHg respectively on average in patients with large postural drops. SO if you are seated or lying for long periods these can be used to reduce symptoms. PREACT is 30 seconds of lifting and pumping your legs like riding a bike. TENSE involves crossing your ankles then tense the whole legs to force the blood up to the heart.

Medications for heart rate:

1. Ivabradine is the usual medication of choice. It comes in 5 and 7.5mg doses and is used to slow the heart beat in certain patients with heart failure. It also very helpful to settle the racing heart in POTS with no drop in blood pressure and has no common side effects. The tablet lasts up to 11 hours so 1 morning dose can usually last through most of the active day but an afternoon half or full tablet be used if required prior to exercise. As it is a private script it costs ~$40/box of 56 tablets.

2. Verapamil/Diltiazem are Calcium Channel Blockers and these will also drop the heart rate similar to Ivabradine with a long acting version lasting up to 18 hours and a faster onset short acting tablet lasting ~6 hours. These tablets will drop blood pressure a small amount but often patients feel well due to the concurrent normalisation of the heat rate, These can have the side effects of constipation, ankle swelling an headaches but are generally well tolerated. These can be used in isolation or in conjunction with Ivabradine. A good option for overnight suppression for patients with overnight palpitations, especially as they are cheaper than Ivabradine,

3. Beta blockers are the stronger cousin to the Calcium Channel Blockers. These also have longer lasting options like atenolol (18 hours), medium like metoprolol (12 hours) and short acting like propranolol (~6 hours). They do drop blood pressure a little more than the calcium channel blockers and can have more side effects (tiredness, fatigue, nightmares, but can have a mood stabilising effect making people less stressed. They will worsen asthma in those who suffer from it. Similar to the calcium channel blockers are a good option for night time and sometimes in the morning combined with Ivabradine.

Medications for Dizziness:

1. For those with the postural drop and dizziness despite the lifestyle changes and stockings the addition of Fludrocortisone 0.05-0.2mg in the morning can help retain extra fluid in the system.

2. Midodrine is one of the stronger medications to drive up blood pressure and can be taken once, twice or three times a day as it is not long lasting and can be adjusted to dose effect to drive up blood pressure so once standing the blood pressure does not drop too low but it also speed up the heart rate further.

Other medications:

It is worth considering whether certain tablets that exacerbate the condition can be reduced, stopped or swapped as some worsen the postural hypertension including anti-hypertensives, diuretics, pain relief, anti-depressants.

Other medications can increase the heart rates including: stimulants and anti-depressants.

Research Areas:

Intravenous infusions of IVIG (Antibodies) are used in many neurological and haematological conditions and are now being trialled to counter those patients with autoantibody issues to help switch off the condition.

Road to Recovery…

Often POTS is difficult to cure or switch off in short period unless the associated conditions are also short likely some post viral conditions. Typically POTS will condition whilst there is ongoing deconditioning and inability to exercise and do muscle strengthening. The main purpose of the medications and lifestyle changes is to help facilitate progressive improvement in physical function, return to normal activities and improvement in symptoms until a level is reached that the medications can be weaned down, the stockings can come off and the postural changes disappear.

Further information:

Information can be found on the POTS foundation pages in various countries including Australia: https://potsfoundation.org.au/

Various assessment sheets and diagnostic criteria for overlap conditions can be found here: https://potsfoundation.org.au/diagnosing-pots/

There are multi-disciplinary clinics specialising in POTS and its overlap conditions as most cases are more than just isolated POTS.

Consideration for referral to a Cardiologist with interest in POTS, ideally with the lying standing results or a holter can be used but is typically incorrectly reported as normal (as most reporters are just looking for abnormal rhythm and not rates. Look for excessive tachycardia with minimal activity, sudden rises in heart rate, hourly maximum heart rates >100bpm all day and night and changes in heart rate variability.

Depending on the overlap conditions present referrals may include Immunology for MCAS or auto-antibody concerns (Hashimoto's); Rheumatology may provide assistance with Fibromyalgia, Neurology with post concussions syndromes, gastroenterology or gynaecology for chronic abdominal issues, Psychiatry/Psychology for eating disorders, anxiety and depression, ADHD management

The cornerstone is a graded exercise program mainly aiming on leg and core strengthening and slow increase in cardiac fitness as your body’s exercise threshold allows. Programs can be obtained to be performed on your own but often is best to be run by a supervised physiotherapist or exercise physiologist, ideally with experience in POTS. An incorrect or too aggressive approach may lead to excessive symptoms and prolonged recovery post sessions and inexperienced programs will not understand the intricacies of managing this condition.

Last comments:

POTS in itself is not a cardiac condition and does not require cardiac involvement but the diagnosis can be made simply when assessed properly and requires a coordinated approach and experienced teams to help address early and correctly.

POTS is commonly missed as a diagnosis along with the overlap syndromes for quite some time and the delay in diagnosis often leads to worsening deconditioning, worsening of symptoms and a much longer protracted recovery.