The doctors at Vanderbilt often are ahead of other centers on research in POTS. However, this summer they were usurped by a doctor in Texas who did some fascinating research into primary POTS patients. These patients (to my understanding only 19 which is a small sample size indeed) were all young women (with maybe a man or two for good measure) who had adolescent onset POTS. In many cases, POTS strikes young women in their teen years following puberty and perhaps some viral or bacterial infection. The theory has been that these teens have a primary form of POTS as a result of deconditioning or a partial dysautonomia. The study done in Texas showed that, in actuality, these young people had small hearts that produced inadequate stroke volumes.
What does that mean? Well, stroke volume is the amount of blood your heart pumps out into the body with each beat. This amount multiplied by the heart rate creates a number called cardiac output (ml stroke volume X bpm heart rate= cardiac output). Cardiac output is therefore the amount of blood pumped by the heart every minute. As the stroke volume decreases, the body increase the heart rate to compensate and maintain a normal cardiac output, hence the hallmark tachycardia of the POTS patient.
It was also observed that for whatever reason, these young women also had lower blood volume than normal. The study was fascinating, in that is found a clear and measurable deficit in stroke volume and blood volume. But the researchers did not stop there. They wanted to show a way to change this state in their patients. And so they used recumbent exercise in the form of a rowing machine, to recondition their patients. They also found that for these young women, the exercise helped them to increase their blood volume (although there is no accounting for outlying factors such a fluid intake) and improve stroke volume. We all know that the more fit an individual is, the more efficient the heart works. This study capitalized on this concept, by reconditioning the patients in a manner that was tolerable for the patients (difficult to do for people whose heart rates are miserably high).
This study offers great hope for many POTS patients, but comes with several serious caveats. One, the sample size was small. Two the sample size was limited to those who were young and had a form of POTS that is poorly understood to start with. There was no sample for those with other forms of POTS, concurrent disease and disorders, or secondary POTS. These were otherwise healthy participants, with a clear pathophsyiological abnormality, and a clear treatment option. Reality is never that controlled, therefore these results cannot be generalized. But worse, they negated any sense of respect for their work from the POTS community at large by carelessly referring to their newly identified syndrome as "the Grinch syndrome" (so called because of the small heart). It is hard to take any scientist seriously who relates you and your condition to a Dr. Seuss character. Still, this information could be helpful to some.
In my, I was willing to try, and so investing in a small rowing machine for home use. After looking at the box on my floor for two months while my Hickman insertion site healed, I finally assembled it today. Well, in all honesty a friend of mine did it while I looked on and added comic relief. When it was completed, I sat on my new machine with anticipation. Then I flailed around on the thing for a few minutes while I tried to coordinate my motions enough to make the thing work. Once I figured it out, it was surprisingly easy. Or so I thought.
After a few minutes I was not only out of breath, but my heart rate was 180 and my muscles were burning. I crawled off with jello legs and sat nearby while my friend easily did three times the work. I was actually rather impressed that I did it at all. But within a few hours, my pride was quashed by the burning pain my shoulder (never a great joint that has nagged me for years now) and the movement of cramps running up and down my back muscles. It was charming. Still, for me it was a revelation. Is this something that I can truly do? It was hard when doing it, and it would seem that can build up to more slowly without the orthostatic challenge of an upright exercise. So although my body hurts madly, I feel a little bit of hope again. And that alone is worth the trouble. :)
