(50 min interview with Systrom)
Emerge Australia Imagine Podcast Series, 1/18/24: “
Dr David Systrom”
“the silver lining..,at least with respect to research interests and funding, from the long COVID pandemic really has been additional money and interest in the direction of ME/CFS”
“I am excited globally about the very notion that you mentioned earlier that long COVID has spawned interest respect research treatments into ME/CFS. So that globally excites me..And so the fact that all of this has begun to come around not only for long COVID, but for ME is super exciting.”
“we all know that ME/CFS was given short shift for a long, long time and continues to be to a degree by the medical establishment. And yes, then along came long COVID and really got people's attention, both because of the incredibly high incidence and then prevalence, but then the similarities, as you mentioned in your introduction to ME/CFS.”
“first part was the discovery, initially with ME and then with long COVID, that there is evidence, we think, of neurovascular dysregulation during acute exercise. And we've come at that from a couple of major lines of evidence.”
“So pretty universally in both ME/CFS and long COVID, we will observe what we call preload failure. And these are exceedingly low pressures feeding the right heart. And in the upright position, many of our patients know gravity is the enemy.”
“What we're seeing is a tendency of blood to pull in the legs and the abdomen & failure of the autonomic nervous system to squeeze down the big veins, push physically blood back up northward to the right heart..see that w/these low filling pressures, again, called preload failure...we found something similar on the arterial side. And at the end of the day, I think it's mostly about lax blood vessels. They're abnormally dilated. And on the arterial side, what that means is an individual perfuses or sends blood flow inappropriately to organ systems that do not need it.
So our best guess is that blood is going to places like the gut and the kidney and even the skin, in large volume when it should be directed by the autonomic nervous system, toward the exercising muscle. And that fails to happen. And what we see is evidence of impaired oxygen extraction by the muscle. So the blood is going to where it's not needed. And what suffers is the oxygen delivery, the appropriate oxygen delivery to the muscle where the mitochondria can take it up and use it. So we see evidence of impaired oxygen extraction coming back at the tip of this pulmonary artery catheter at maximum exercise.”
“we've also increasingly recognized over recent time that these same nerve fibres normally play a major role in blood vessel tone. So what we found in that Philip Joseph paper was that nearly half of the patients that we did skin biopsies on and this invasive exercise test had evidence of the small fibre neuropathy by a skin biopsy. So that's how we come to the conclusion that this is quote, neurovascular dysregulation. The exercise test shows us abnormally dilated veins and arteries and abnormal blood flow. And the skin biopsy, which we marry in a sense to the exercise test, tells us that there is a very high prevalence of small fibre neuropathy.”
“Last little bit, this is unpublished. More recently, we've done dual skin biopsies with Peter Novak, who is a world renowned neurologist at Brigham Faulkner. Peter's Autonomic Function Lab does the initial superficial skin biopsy above the ankle.
That's the so-called epidermal biopsy, but additionally does one a little deeper up in the thigh. And what we can get then is sweat glands and their innervation by these small fibre nerves. And what we found is nearly two-thirds of patients with both ME and long COVID have evidence of small fibre neuropathy when we do the deeper biopsy and we get the sweat glands.”
"So we think we've begun to build a case for neurovascular dysregulation in both diseases as a cause for symptoms"
