There has been a lot of interesting news about POTS recently. I want to share one study in particular with you that I think you will find interesting.
Since it was first categorized, specialists have speculated about the origins of postural orthostatic tachycardia syndrome (POTS). Early studies such as this one suggested that, due to the presence of ganglionic acetylcholine receptor antibodies in some POTS patients, POTS may be autoimmune in origin. Additionally, in some patients POTS is triggered by an autoimmune condition such as Sjogren’s, lupus, or diabetes.
More recently, researchers have tested the hypothesis that POTS may have an autoimmune basis by testing POTS patients for adrenergic receptor autoantibodies. The study and its results were published in the Journal of the American Heart Association and are very technical and nature. I’m not a doctor, nor do I play one on t.v., so I admit to struggling with some of the contents of the journal article. However, Dysautonomia International gave a good summary here that I highly recommend.
Essentially, POTS patients and healthy control subjects were tested for alpha andrenergic receptor (α1AR) autoantibodies. Andrenergic receptors are protein receptors that are present on the surface of many cells. These protein receptors bind with certain chemicals such as epinephrine (adrenaline) and norepinephrine. This stimulates the sympathetic nervous system which is responsible for the “fight or flight” response, and the receptors send messages for the body to react by dilating pupils, increasing heart rate, etc.
As I have mentioned in the past, it is not unusual for some POTS patients to experience an overexaggerated adrenaline response at inappropriate times. I sometimes get adrenaline rushes as inopportune times, such as when I’m sitting in a meeting. Client’s don’t seem to appreciate my sudden desire to “fight or flight” 🙂
Antibodies are proteins that fight off foreign invaders to your body, such as a virus or bacteria. Autoantibodies are antibodies that have malfunctioned and are attacking your own cells. So, andrenergic receptor autoantibodies attack the andrenergic receptors on your cells.
According to Dr. Kem (who authored the journal article):
These autoantibodies interfere with the system which controls the ability of blood vessels to constrict, which is needed to prevent a drop of blood pressure as a person stands. In POTS patients, this inadequate response to standing leads to a generalized increase of activity in the body’s sympathetic nerve system, which frequently normalizes the blood pressure. This increased nerve activity, however, increases the heart rate which is a prominent symptom in POTS. (as quoted on Dysautonomia International blog)
The results of the study showed that, compared to the healthy control subjects, the POTS patients showed elevated levels of the autoantibodies, suggesting the autoantibodies may be responsible for the abnormal heart rate response in POTS patients.
So what does this mean? POTS may be autoimmune in nature in some patients.
Why does that matter? As Dr. Kem stated, “We hope to eventually develop treatments to block these autoantibodies, without blocking the target receptor proteins at the cell surface at the same time.” Certainly more research is needed, and these findings may not apply to ALL cases of POTS, but it could mean that there is a more effective treatment on the horizon.
And THAT, my friends, is good news.
“Rivers know this: there is no hurry. We shall get there some day.” – A.A. Milne, Winnie-the-Pooh
Smell ya later.