INSIGHT WITH POTS: PRACTICAL APPLICATIONS
Postural Orthostatic Tachycardia Syndrome (POTS) has been discovered only recently. Therefore, the research into this condition is new and usually involves small groups of people. The American Autonomic Society focused on research in the 2007 Streeten Lecture in Vienna, Austria. The overall goal of that presentation was to compare and contrast POTS with physical deconditioning. Individuals interested in POTS might find my review of that presentation to be interesting.
What is POTS? POTS is marked by normal heart rhythm at rest with no evidence of underlying heart disease, but with a sustained increase in heart rate of more than 30 bpm with 10 minutes of upright posture. However, there is no sustained or marked drop in blood pressure in this upright position. Even with normal blood pressure, patients frequently complain of lightheadedness, weakness, palpitations, blurred vision, breathing difficulties, nausea and headaches. These symptoms resolve when they return to the supine position.
Is POTS psychogenic? Because doctors can’t find anything “obviously” wrong with patients who have POTS, they may conclude that this problem is psychogenic (all in your head). To study this more completely, investigators from the Mayo Clinic did careful research evaluation of 14 patients with the diagnosis of POTS. When patients have a tilt table test, gravity pulls blood to the legs when patients are upright. In order to mimic these changes, special trousers can be placed on a person and then subjected to a vacuum. This is called lower body negative pressure (LBNP). Patients with POTS showed exactly the same response to LBNP as they did with being tilted upright.
Then, to test if this might be psychologically induced, the investigators tried to trick patients by telling them they were going to turn on the vacuum and create negative pressure but in fact the machine created its typical sound, but no vacuum was created. None of the patients had an increase in their heart rate. In addition, these patients did not have an excessive heart rate response to mental stress. There is no doubt about it: for patients with POTS, this increase in heart rate is the real deal.
POTS and the perception of discomfort: On the other hand, this testing of the psychological aspects of POTS also demonstrated something else. That is, patients with POTS are much more sensitive to things that happen to their bodies and they report it in a much more dramatic way than other people do. This is called somatic hypervigilance. For example, when tested for their pain threshold, individuals with POTS have a tendency to report their response more intensely than other people. This includes both their sensitivity to anxiety, and how much they notice changes within their body. The most dramatic increase for POTs patients was their tendency to consider an event to be a catastrophe when compared to control patients.
Are the changes of heart rate and venous pooling really abnormal? One problem that patients have with POTS is that they learn it is related to the autonomic nervous system and then they go to the Internet. When they look up autonomic disorders, they find postural orthostatic tachycardia syndrome. Nearby, either on the same page or with a link, they may find other things like pure autonomic failure (PAF). Unlike POTS, PAF is a horrible disease with relentless disease progression and agonizing clinical problems for which there is no effective treatment. So, are the changes with POTS really abnormal? Does this bear any similarity to other diseases of autonomic dysfunction?
Meticulous research in POTS patients has determined that there is only one group of people who respond in exactly the same way. Those are astronauts who were studied prior to space flight and on the landing day. Their responses are nearly identical.
Space flight gives us a unique opportunity because we can study people before and after the situation occurs. Most POTS patients are running around enjoying life before they develop their problems, so we don’t have a “before” and “after” evaluation. What we have learned about space flight is that lack of gravity causes the amount of blood volume to be reduced and it causes the heart to get smaller. This is characteristic of deconditioning. It supports the idea that POTS is a manifestation of exaggerated deconditioning. It also gives us a clue as to why certain drugs may be effective. The medicine Florinef helps to increase the blood volume. Midodrine helps to improve the blood pressure in spite of the low blood volume.
So, what is the next step? This research leads us to several conclusions. First, POTS is not psychogenic. That is, it is not “all in your head” but this racing heart is the real thing. At the same thing, the perception that patients have is likely to be exaggerated compared to that of another person who might have a similar increase in heart rate. We do have considerable control over this aspect of things. Usually, when people tell us to “chill out” they do so because we have become excessively concerned about something going wrong in our lives. We know is it difficult to control our responses at these times, but it is possible and sustained daily effort in this regard might be beneficial.
Second, it should be very reassuring for everyone who has POTS to know that this is not a major medical problem, and it holds nothing in common with the serious disorders of autonomic function that are described on Internet websites. In fact, the only thing it really resembles is the change that occurs in astronauts who have been subjected to zero gravity.
Although we haven’t been able to do much research for patients with POTS, we have poured billions of dollars into the space program, so we know a lot about astronauts. We know that space travel is associated with a loss of blood volume and with decrease in the size of the heart. We also know that the only truly effective treatment for this is exercise. For astronauts, just being back in the influence of the earth’s gravity represents a form of exercise. It turns out the same thing is true for people with POTS. Some find that raising the head of the bed just a few inches provides just a little extra gravitational stress and helps relieve symptoms. The most important aspect of our understanding of POTS is that symptoms can be dramatically improved by endurance exercise training. Patients with POTS will exercise and have an exaggerated sense of fatigue afterwards. First of all be reassured that is completely normal. Secondly, use that to adjust your exercise intensity so you can do this with commonsense.
Final statement: It is very important that patients who have POTS understand that physicians have worked hard to learn more about this syndrome and that the medical community now has a major understanding of this problem. The most important facts to emerge from scientific study are that this problem is typically temporary, that it is not truly a disease state like the other autonomic abnormalities, and that it will definitely get better with exercise and attention to fluid status. For some patients, medications may be helpful during that reconditioning program.
Felix J. Rogers, D.O.
June 9, 2009
Insight with POTS: Practical Applications, June 2009