While COVID vaccines have saved millions of lives worldwide by reducing the overall severity of the disease, almost one in ten of those recovered still end up with persistent symptoms after the onset of the original disease.
These patients present with a staggering set of over 200 symptoms, including dizziness, diarrhea, shortness of breath, fatigue, and a debilitating brain fog that can linger for months or even years.
It is disappointing that even long-term patients with COVID describing breathing problems show normal results in standard clinical breath tests, says respiratory specialist Michael Nicholson of St. Joseph’s Health Care in London.
But a new imaging technique has already clearly revealed the source of the breathing problem.
“The findings allowed us to show that it has a physiological effect on [patient] lungs that correlate with their symptoms, ”Nicholson says.
(Alexander Mathison)
The scan shows the extensive damage that COVID-19 can cause to our delicate respiratory system. Whether it is the virus itself or the body’s response to it, some mechanism has effectively cut off the function of patients’ pulmonary vessels, cutting off many of the smallest, where the extremely important gas exchange takes place.
Researchers led by physicist at Alexander Mattison University in the West instructed 40 volunteers – 34 with post-acute COVID-19 syndrome and 6 without – to inhale a polarized xenon gas isotope. The gas resonates with a certain frequency in MRI, which allows researchers to monitor the activity of the small airways and blood vessels in real time.
“For those who are symptomatic after COVID, even if they have not had a severe enough infection to be hospitalized, we see this abnormality in the exchange of oxygen across the alveolar membrane in red blood cells,” said Western University biophysicist Grace. Paraga.
“What we saw on MRI was that the transition of oxygen to red blood cells was suppressed in those symptomatic patients who had COVID-19 compared to healthy volunteers.
Because flu symptoms are the most obvious and common signs of COVID-19, it is often dismissed as just another respiratory disease, but COVID-19 is actually also a vascular disease, which means it can interfere with the circulatory system. The viral particles are directed directly at the endothelial cells that line the walls of our blood vessels and the heart.
Vascular damage is reflected by MRI scan; CT scans also confirm abnormalities in the finest blood vessels in our lungs.
Moreover, a previous study has already demonstrated a change in the distribution of blood from smaller to larger blood vessels in the lungs of hospitalized patients with COVID.
The team proposes several potential mechanisms for change in gas exchange, which were witnessed, illustrated in the diagram below.
Possible mechanisms for impaired gas exchange. (Matherson et al., Radiology, 2022)
The vessels may lose their flexibility, which reduces the amount of blood available to bind xenon to (B), new blood flow patterns due to changes in the vessels elsewhere may bypass the blood away from the gas exchange regions (C) or there is a physical blockage that prevents the blood from reaching it (D).
Matheson and colleagues warn that the small sample size limits their ability to summarize, but insist on further research. And whatever the mechanism behind this, it’s clear that catching the virus can really upset the circulatory system.
Despite easing restrictions in many parts of the world, the global pandemic continues, and any SARS-CoV-2 infection risks 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 walk without panting,” explains one study participant, an Olympic bobsled gold medalist. Alex the Digger. .
“The message for me is that we need to remember that this virus can have very serious long-term consequences that are not trivial. In my case, before I got sick, I didn’t think it would really affect me. “
This study was published in Radiology.
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