Coronavirus can cause deadly blood clots, as revealed by a study by Irish doctors. At work, they found that the infection can cause “hundreds of small” blockages in the lungs, and these clots can damage lung function.
The investigation, led by James O’Donnell, a consulting hematologist at the National Center for Coagulation at St James Hospital, Dublin, continued US reports that blood clots are likely responsible for a “large number” of deaths from coronavirus, even after a patient is discharged from the hospital.
The study emphasizes these risks and explains that ethnicity plays an important role in the effects of blood clotting. The Chinese are at a lower risk of blood clots overall, probably due to genetic differences.
As the team in Ireland explains, blood clotting is more risky for Caucasians, specifically venous thromboembolism. “Ethnicity has significant effects on the risk of thrombosis, with a three to four times lower risk in Chinese compared to Caucasians and a significantly higher risk in African Americans,” explains the study, published in the British Journal of Haematology. “Given these data, it is clearly important to determine if there are differences in coagulopathic characteristics in COVID-19 infected Caucasians compared to Chinese patients,” adds the report.
“Given that thrombotic risk is significantly affected by race … our findings raise the intriguing possibility that pulmonary vascular disease (disorder of the blood vessels in the lungs) may contribute to the unexplained differences that are beginning to emerge, highlighting racial susceptibility to COVID-19 mortality”, Details the work.
The death rate per 100,000 people in the United States was 15.27 on April 24, compared to just 0.33 in China, according to mortality analyzes from Johns Hopkins University.
Research from the National Coagulation Center at St James Hospital in Dublin studied 83 seriously ill patients with COVID-19. 81% were Caucasian, 12% Asian, 6% African, and 1% Hispanic. The patients were, on average, 64 years old, and 80% had underlying health problems. More than a quarter (27%) were admitted to the ICU during their illness. At the time of publication, 60% had recovered and 15.7% of patients had died.
Doctors measured various aspects of the patients’ blood to see how quickly it clotted, which is called a clotting test.
One indicator, called D-dimer levels, was above the normal range at 67% of the total at the time of hospital admission. D-dimer is a substance that remains in the blood when a clot has occurred, so high levels indicate a problem.
The results revealed that patients who showed increased blood clotting activity were more likely to need to be admitted to the Intensive Care Unit (ICU).
Scientists suggest that abnormal blood clotting occurs in the lungs specifically, causing many “micro clots.” “Our novel findings demonstrate that COVID-19 is associated with a unique type of blood clotting disorder that is primarily concentrated in the lungs,” said the author, Professor James O’Donnell. “This undoubtedly contributes to the high levels of mortality seen in patients with COVID-19.”
In addition to pneumonia that affects the small air sacs inside the lungs, we also found hundreds of small blood clots in all of the lungs. This scenario is not seen with other types of lung infections.
“Understanding how these micro clots form within the lung is critical in order to develop more effective treatments for our patients, particularly those in high-risk groups,” he explained.
The authors of the article said it is not clear how the virus leads to blood clotting, but one theory is based on ACE2 receptors. ACE2 receptors have been said to function as the gateway for the coronavirus to the body and “facilitate” infection.
And they have been causally linked to a lower risk of infection and disease severity in smokers, because nicotine is thought to affect ACE2 expression in several ways.
Professor O’Donnell and colleagues said that ACE2 receptors are expressed in cells of the lungs, including endothelial cells of organ blood vessels. Endothelial cells play a very important role in regulating blood flow and in the prevention of blood clotting. Therefore, the damage caused directly by the virus could cause rapid coagulation activation.
But another theory is that clots form as a result of an excessive immune reaction called a “cytokine storm.” Cytokines are chemical signaling molecules that guide a healthy immune response. They tell immune cells to attack the body’s viral molecules. In some patients, this process is accelerated and the immune cells begin to destroy healthy tissues, which is known as a cytokine storm.
The cytokine storm associated with COVID-19 infection will have a major impact on thrombin generation. Thrombin is an enzyme that catalyzes blood clotting. She is involved in stopping a wound as small as a paper cut from bleeding. It helps create a fibrous mesh that prevents blood flow with a protein called fibrin. Fibrin can deposit in the lungs, causing excessive clotting.
Considering all this, the scientists said that the acute respiratory distress syndrome (ARDS) seen in COVID-19 patients may be the result of a “double whammy” of damage to the lungs. Both ventilation of the lungs, which is the flow of air to the lungs, and perfusion, which is the flow of blood to the capillaries outside the lungs, may be damaged. This, in turn, would lower oxygen levels in the body because it disrupts a vital process called gas exchange.
Gas exchange is when the inhaled oxygen reaches the bloodstream and then into the vital organs. It occurs at a junction in the lungs between small sacs in the lungs called alveoli and blood from small vessels on the outside called pulmonary capillaries.
For gas exchange to be effective, the alveoli must always be adequately ventilated and perfused.
The micro clots “explain why blood oxygen levels drop dramatically in a severe COVID-19 infection,” said Professor O’Donnell.
Other researchers investigating the relationship between blood clots and COVID-19 say that the unique form of COVID-19 may allow it to adhere to blood vessels as it invades the body, damaging them and causing leakage. Or the cytokine storm can lead to damage to leaking blood vessels that cause blood pressure to plummet, increasing the chance that clots will form.
Jamie Garfield, a pulmonologist at Temple University Hospital in Philadelphia who cares for a COVID-19 patient, told the magazine Science that this was “probably” the true reason for many coronavirus deaths.
Although this study focused primarily on clotting in the lungs, blockages near the heart can lead to a heart attack, another common cause of death in infected people. And clots on the chest can cause strokes.
For example, 38% of Dutch ICU patients had blood clots, according to an April 10 study published in Thrombosis Research.
Between 20 and 40 percent of COVID-19 patients at Emory University in Atlanta, Georgia, have developed blood clots – even after being put on blood thinners.
“One of the things we discovered about COVID is that it causes clotting problems, that is, thrombosis (blood clots) found in both the great vessels and the microvasculature,” said Paul Saunders, a physician at the Maimonides Medical Center, in dialogue with him DailyMail. “That has been found at multiple sites in the body – for example, blood clots in the legs, small clots in all the lungs, as well as large pulmonary emboli.”
Other data suggests that clots that start in the lower body can migrate to the lungs, causing a deadly block called pulmonary embolism.
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