margarita25
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Blood Clots CV
Many patients are developing small-clots in their lungs, reducing the amount of oxygen they can move into their bodies. For others, their blood is clogging dialysis machines (which has been a problem due to the amount of kidney failure this illness is also causing).
“I’m a hematologist, and this is unprecedented,” says Jeffrey Laurence of Weill Cornell Medical College, who has been in the field for three decades. “This is not like a disease we’ve seen before.”
Nearly every patient he has seen for blood disorders in the past month and a half has had Covid-19. “I’ve never had so many consults in my life. These people are clotting, and we can’t shut it off.”
Blood clots are also causing other unexpected problems for Covid-19 patients. For example, Broadway actor Nick Cordero, who has been hospitalized since March with severe Covid-19, had his right leg amputated earlier this month after doctors were unable to control clotting there.
What causes blood to clot?
When we get injured, we depend on our blood’s ability to clot to stop the flow of blood. Clotting is a complex process that involves small cell fragments called platelets congregating and changing shape, proteins that help even more cells bind together, and the secretion of substances called blood clotting factors. If any of these processes go off course, people can experience excessive bleeding, which can be life-threatening.
On the other end of the spectrum, sometimes clots form inside blood vessels (or, more rarely, arteries) without an injury. These can cause serious harm and sometimes death. There are many risk factors for developing internal blood clots, including smoking, obesity, heart disease, and others. And, now, it looks like Covid-19 is a risk factor as well.
Some clots remain in the place where they form and are known as thrombosis. This can cause severe pain and swelling. These clots can also travel to — or form in — a major organ, where they can do even more serious damage.
For example, a clot in the leg can travel up to the lungs, cutting off blood flow and causing a pulmonary embolism (which can lead to death or permanent lung damage). A clot can also flow to the heart, triggering a heart attack. And one in or near the head can block blood flow in part of the brain, bringing on a stroke.
What clots are doing to Covid-19 patients
Small early studies and case reports about the link between the novel coronavirus and blood clots are now pouring in. For example, one team in the Netherlands followed 184 severe Covid-19 patients who were receiving treatment in three different intensive care units. They found that 31 percent of these people had some sort of blood clotting issue, a percentage they call “remarkably high.”
Other data is emerging with similar implications. “In patients with severe disease, various forms of blood clots are estimated to occur in 15-35 percent of patients,” Behnood Bikdeli, a cardiology fellow at Columbia University Medical Center, tells Vox. And these clots, especially the small ones, “could impact the illness severity and involvement of many of the organs,” he says. (He and an international team of dozens of researchers published an April review of clotting issues in the Journal of the American College of Cardiology.)
Laurence has been studying small blood clots in HIV/AIDS patients for decades. In March, a dermatologist sent him a photo of surprising skin lesions on a young man who was severely ill with Covid-19. Laurence was stunned. “It’s a picture of microvascular clotting, where you can see exactly where the vessels have clotted,” he says. He started wondering if something similar might be happening in the lungs.
Just hours later, another doctor called, giving him access to an autopsy of a different Covid-19 patient. Not only did this individual have small clots in the skin — but also in his lungs. (Laurence and his colleagues published descriptions of these and three other cases of severe clotting in an April Translational Research paper.)
The presence of small clots in the lungs is disturbing, but it also might help to explain a puzzling trend medical staff have noticed in some Covid-19 patients. When people develop more advanced illness, their lungs can become stiff, making breathing on their own very difficult. This leads to a drop in oxygen in the blood if they are not on mechanical ventilation.
But health care workers have seen many patients with low oxygen levels but who still have fairly flexible lungs, Laurence explains. This points to the presence of “microvessel clots [in the lungs] shutting off the ability of people to bring oxygen into their blood,” he says. (He also noted that sustained time on a ventilator can, itself, increase lung stiffness, which could have been throwing off clinicians who were seeing that as an outcome of the illness, and perhaps along the way missing signs that something else was going on.)
Laurence also describes the multitude of people sick with Covid-19 whose blood clots are plugging up the dialysis machines in their wards. Beyond that, he says, even “as the nurses are drawing their blood, it’s clotting in the tubes, and they’re on full doses of Heparin” and other blood thinning medications. “Everyone is seeing a similar kind of thing,” he says. (More in article)
How Covid-19 might be causing blood clots
Scientists still don’t understand exactly what is triggering this excessive blood clotting. (Some viruses, such as the Ebola virus, cause extreme bleeding, but others, such as HIV, can trigger small clots.) And it’s not yet clear if these changes in the blood are from the virus itself or the body’s immune response to the infection.
One of the hypotheses has to do with how the virus gains entry to our cells. Researchers have found that this coronavirus manages to sneak into our cells via a specific type of receptor known as ACE2. These are prominently found in the lungs, which might explain why so much of the virus’s damage has been centered there. But ACE2 receptors are also very common along the walls of blood vessels throughout the body, Oxley explains. So it’s possible that its presence there is spurring additional inflammation of the vessels, prompting the formation of blood clots.
Laurence also points to this inflammatory problem. “It is this insidious feedback loop of inflammation,” he says. And once it’s going, he says, “you can’t intervene in that system effectively.”
To be sure, sustained immobility, such as in a hospital bed, can increase the risk for blood clots, but the rates currently being reported in Covid-19 patients is way above what would normally be expected, Laurence notes.
What can be done
With the new evidence about this virus’s potential effect on the blood, doctors at many major medical facilities have begun administering low doses of preventative blood thinners to Covid-19 patients.
It’s a tricky move, though, because too much blood thinner can cause a patient to bleed internally and possibly die. To gauge the best doses, many physicians are going off of a patient’s D dimer levels, which is a biomarker for the presence of blood clots. New clinical trials have quickly spun up (including a multi-state one in the US to test one type of powerful blood thinners, known as tPA (tissue plasminogen activator) in Covid-19 patients, as STAT News reports). And Bikdeli and others have formed an international collective “to provide interim consensus-based guidance,” he says. “What is needed most is high-quality data.”
But these preventative treatments won’t help those who’ve had strokes or other major blood-clot complications before receiving medical care. And that number, though still small, is real, as the five young stroke victims from New York City show. (More in article)
Coronavirus’s new mystery: It’s causing strokes in healthy people
Ugggh yeah I was reading about “micro clots” the other day and it totally freaks me out and gives me the heebie jeebies moo, like nails on a chalkboard. Got goosebumps now in fact...
