P.O.T.S.
Postural Orthostatic Tachycardia Syndrome (P.O.T.S.) is a condition defined by excessive heart rate increments upon upright posture. A normal heart rate is between 60 and 80 beats per minute. The heart rate of a P.O.T.S. patient increases by at least 30 beats per minute when the patient stands up and/or increases to at least 120 beats per minute when the patient stands up. These large increases in heart rate usually occur within 10 minutes of standing up. It is estimated that a P.O.T.S. patient uses about three times as much energy as a healthy person does just to stand. Exercise and strenuous activities such as housework can severely exacerbate symptoms. In many cases simple tasks such as bathing and meals are exhausting. Patients may also experience dizziness, chest pains, shortness of breath, blurry vision, sweating and tingling sensations in the legs when standing. Veins in the legs become dilated, which causes blood “pooling” (extra blood collects there) and the legs may become a reddish colour as a result. Other symptoms include difficulty swallowing, fevers, chills, hypoglycaemia and numbness. Sleep problems are also common with P.O.T.S. and as a result patients also experience fatigue and problems with memory and concentration. Research shows that P.O.T.S. patients’ quality of life is similar to those with congestive heart failure and chronic obstructive pulmonary disease. Most patients have to make some radical adjustments to their lifestyle in order to cope with this disorder. There are two main forms of P.O.T.S:
1. Partial Dysautonomic (the most common form of P.O.T.S.)
2. Hyperadrenergic P.O.T.S. |
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This is the most common primary form of P.O.T.S. Partial Dysautonomic P.O.T.S. usually begins suddenly and out of the blue. As well as the symptoms mentioned above, these patients usually suffer from a much greater than normal degree of blood pooling when standing, which causes the heart rate to increase. |
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Image from the Indian Pacing Electrophysiology Journal |
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Patients who have Hyperadrenergic P.O.T.S. experience a gradual and progressive onset of symptoms as opposed to an abrupt onset. Hyperadrenergic P.O.T.S. patients experience significant tremors and sweating in the extremities when standing. Over half of these patients suffer from migraines and many have the need to urinate more frequently than normal whenever they are standing even if only for a short period of time. The main difference between this form of P.O.T.S. and other forms, is that in addition to orthostatic tachycardia (rapid heart rate when standing), patients with Hyperadrenergic P.O.T.S. often display orthostatic hypertension (high blood pressure when standing). Patients with this form of P.O.T.S. also react differently to certain medications than patients with Partial Dysautonomic P.O.T.S.
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There is often a family history of this disorder. Research indicates that Hyperadrenergic P.O.T.S. may be caused by a single genetic mutation. This in turn leads to a sequence of events that present themselves as the symptoms of Hyperadrenergic P.O.T.S. Many patients develop P.O.T.S. following pregnancy, surgery, a virus or infection. Some other triggers of P.O.T.S. include adverse reactions to medications or immunisations, or exposure to toxic chemicals. Ehler’s-Danlos Syndrome has recently been recognised as a trigger of P.O.T.S. and there is strong evidence to suggest links between P.O.T.S. and Hypermobility Syndrome and Myalgic Encephalopathy, which are being researched. |
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There are lots of different types of test for P.O.T.S. but the most commonly used test is the “tilt table test” where the patient is strapped to a table that is gradually tilted. The patient’s blood pressure and heart rate are measured throughout the test. Reactions to certain drugs may also be tested in order to determine a diagnosis of P.O.T.S. and blood and urine tests will be taken to rule out any other possible causes of the symptoms |
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There is no cure for P.O.T.S. but there are various medications available to treat the symptoms. These have varied success from one patient to the next, depending on their specific symptoms and any other underlying conditions. Although it is the last thing a P.O.T.S. patient feels like, exercise can help in many cases because it stimulates the body to produce norepinephrine, which constricts the veins, thus limiting the extent of blood pooling. Some dietary changes may also prevent symptoms from being aggravated. Click here to view and print our awareness leaflet about P.O.T.S. |
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P.O.T.S.