Experts Explain: What are Blood Clots in COVID, Do you need to Worry

New Delhi: Experts say that there is increasing evidence to suggest that COVID-19 is not just a disease of the lungs as initially thought but it can also cause dangerous blood clots, which needs to be immediately removed to save limbs in some cases.

Studies have shown that the prevalence of blood clot formation known as deep vein thrombosis (DVT) in hospitalised COVID-19 patients is 14-28 per cent and is a lower 2-5 per cent for arterial thrombosis. Experts said that India is experiencing a similar, stressing that the infection is about the blood vessels as much as about the lungs.

Dr Ambarish Satwik, vascular and endovascular surgeon at Delhi's Sir Ganga Ram Hospital, said that they are dealing with five-six such cases per week on average. This week, it has been one a day of such complications.

On the other hand, Dr Amrish Kumar, consultant, cardio-thoracic vascular department, Aakash Healthcare in southwest Delhi's Dwarka, said that the prevalence of blood clot formation in COVID-19 is high in patients who have conditions such as type-2 Diabetes Mellitus, although the exact incidence remains unknown.

While DVT is a serious condition that occurs when a blood clot forms in a vein located deep inside the body, arterial thrombosis is a clot that develops in an artery. Arteries are blood vessels that carry oxygen-rich blood away from the heart to the body, while veins carry blood low in oxygen from the body back to the heart.

When COVID first hit China and the global west, it was thought that it was typical viral pneumonia. Severe cases of acute COVID-19 were being labelled as similar to the acute respiratory distress syndrome (ARDS), which leads to respiratory failure.

Experts said that in a COVID-19 patient, when blood vessels are injured, they produce a protein that attracts platelets and other clotting factors that come together to form a clot. Studies have shown that around 20 to 30 per cent of hospitalised COVID-19 patients have developed this complication. Because blood vessels are everywhere on the body, these clots could form anywhere. Some of these clots occupy big blood vessels and become macroscopic blood clots.

According to a University of Oxford study published in April, the risk of rare blood clotting following COVID-19 is around 100 times greater than normal. The research found that the rare blood clotting known as cerebral venous thrombosis (CVT) - a blood clot of a cerebral vein in the brain - is more common after COVID-19 than in any of the comparison groups, with 30 per cent of these cases occurring in the under 30s. According to its finding, the study covered 500,000 COVID-19 patients. The risk would be 39 in a million.

Explaining how the virus causes blood clots in COVID-19 patients, experts say that the virus is known to attach itself to the inner lining of the lung, and right next to these air sacs are very thin blood vessels or capillaries. The virus invades these blood vessels and starts affecting the inner lining of these blood vessels which produces a dysfunction within the blood vessels which produces these clots.

It's very difficult to know the prevalence of clots in the entire population infected with COVID-19.

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