Although COVID-19 vaccines have saved millions of lives worldwide by reducing the overall severity of the disease, nearly one in ten of those recovered still have continued symptoms after the initial disease has passed.
These patients present with an astonishing number of more than 200 symptoms, which include dizziness, diarrhea, shortness of breath, fatigue, and debilitating brain fog, which can last for months or even years.
Frustratingly, even long-term patients with COVID who describe breathing-related problems show normal results in standard respiratory clinical trials, says respirator Michael Nicholson of St. Louis. Joseph’s Health Care London.
But a new imaging technique has now clearly revealed the origin of the respiratory problem.
“The findings allowed us to show that there was a physiological impact [patient] lungs that correlate with their symptoms, ”says Nicholson.
(Alexander Matheson)
The scans show the great damage that COVID-19 can cause to our delicate respiratory organs. Whether it’s the virus itself or the body’s response, some mechanism has effectively curtailed the function of patients ’lung vessels, cutting off many of the smaller ones where the important gas exchange takes place.
The researchers, led by Western University physicist Alexander Matheson, instructed 40 volunteers, 34 with post-acute COVID-19 syndrome and 6 without, to inhale a polarized xenon gas isotope. The gas resonates at a signature frequency under magnetic resonance imaging, allowing researchers to observe the activity of the airways and blood vessels in real time.
“For those who are symptomatic post-COVID, even if they had not had an infection severe enough to be hospitalized, we are seeing this abnormality in the exchange of oxygen across the alveolar membrane into red blood cells,” he said. says the Western University doctor. biophysics Grace Parraga.
“What we saw on MRI was that the transition from oxygen to red blood cells was depressed in those symptomatic patients who had had COVID-19, compared with healthy volunteers.”
Because flu symptoms are the most obvious and common signs of COVID-19, it is often ruled out as another respiratory disease, but COVID-19 is also a vascular disease, meaning it can interfere with the circulatory system. . The virus particles go directly to the endothelial cells, which line the walls of our blood vessels and heart.
Vascular damage is reflected on MRI; CT scans also confirm abnormalities in the thinner blood vessels in our lungs.
In addition, a previous study has already shown a change in the blood distribution of smaller to larger blood vessels within the lungs of patients hospitalized with COVID.
The team proposes several potential mechanisms for altering the gas exchange they witnessed, illustrated in the diagram below.
Possible mechanisms for interrupting gas exchange. (Matherson et al., Radiology, 2022)
Vessels may be losing their flexibility, which reduces the amount of blood available for xenon to bind to (B), new blood flow patterns from changes in vessels elsewhere may be driving blood away from the blood vessels. gas exchange regions (C), or there. it is a physical blockage that prevents blood from reaching it (D).
Matheson and colleagues warn that the small sample size limits their ability to generalize, but call for further research. And whatever the mechanism behind this, it’s pretty clear that catching the virus can wrap up the circulatory system.
Although restrictions are reduced in many parts of the world, the global pandemic continues and every SARS-CoV-2 infection runs the risk of vascular damage, from clotting problems to heart disease.
“I was on oxygen for almost two months after COVID, and it took me almost three months to get to a place where I could go for a walk without breathing air,” explains one of the study participants, the Olympic gold medalist. by bob Alex Kopacz. .
“The message that brings me home is that we need to remember that this virus can have very serious long-term consequences, which are not trivial. In my case, before I got sick, I didn’t think it would really affect me. . “
This research was published in Radiology.