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COVID-19 Not Just Lung Disease, Can Also Cause Dangerous Blood Clots: Experts

According to Dr Amrish Kumar, Aakash Healthcare, Delhi, 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

COVID-19 Not Just Lung Disease, Can Also Cause Dangerous Blood Clots: Experts
  • COVID-19 infection is about blood vessels as much as about lungs: Experts
  • We are dealing with five-six such cases per week on average: Doctor
  • The virus invades blood vessels: Doctor

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

Also Read: COVID-19 Vaccine Delivery By Age May Mitigate Deaths And Severe Health Impacts: Study

The India experience is similar, said experts, stressing that the infection is about the blood vessels as much as about the lungs.

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

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, added Dr Amrish Kumar, consultant, cardio-thoracic vascular department, Aakash Healthcare in southwest Delhi’s Dwarka locality.

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.

Dr Satwik drew attention to the COVID-clot connection in a tweet earlier this week in which he posted a picture of a blood clot cast retrieved from the lower limb arteries of a COVID-19 patient.

What COVID clots look like. COVID produces blood clots. The incidence of heart attack, stroke, or limb loss due to an arterial clot in COVID varies from 2 per cent-5 per cent. We pried these out of the lower limb arteries of a COVID patient. We were able to save the limb, Dr Satwik said on May 5.

Also Read: Chef Vikas Khanna Sends COVID-19 Emergency Relief Material To India

Explaining his tweet, which attracted a lot of attention and questions too, Dr Satwik said the COVID-19 patient had an acute circulatory cut off because of the clots, and the limb was threatened.

So we had to physically do a surgical procedure and extract these clots, otherwise there would have been gangrene, and he would have ended up with an amputation. We were successfully able to take the clots out and save the limb, the surgeon explained.

Authors of a Lancet paper published in November last year said studies suggested there is increased association between COVID-19 and the risk of thromboembolism (TE) or obstruction of a blood vessel by a blood clot. The authors of the paper concluded that TE rates of COVID-19 are high and associated with a higher risk of death.

We have been understanding the pathophysiology of COVID-19 for over a year now. When it first hit China and the global west, it was thought that it was typical viral pneumonia. Severe cases of acute COVID were being labelled as similar to the acute respiratory distress syndrome (ARDS), which leads to respiratory failure, Dr Satwik noted.

However, a series of autopsies on COVID patients and their lungs revealed that what the doctors were seeing was not typical ARDS. “…in addition to that, they were finding clots in the microcirculation of the lungs. So it was then kind of understood that COVID is as much a disease of blood vessels as much it’s a disease of the lungs,” Dr Satwik added. 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, Dr Kumar added.

Also Read: Proning Do’s And Don’ts, What Experts Have To Say

Studies have shown that around 20 to 30 per cent of hospitalised COVID-19 patients have developed this complication, he told PTI.

Because blood vessels are everywhere on the body, these clots could form anywhere, Dr Satwik said. Some of these clots occupy big blood vessels and become macroscopic blood clots.

But otherwise we are seeing diffused microscopic clots in microcirculation in various organs, he noted.

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.

The signals that COVID-19 is linked to CVT, as well as portal vein thrombosis a clotting disorder of the liver is clear, and one we should take note of, said Oxford’s Maxime Taquet, one of the authors of the study.

Explaining how the virus causes blood clots in COVID-19 patients, Dr Satwik said 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, the surgeon said.

As a result, he said, some clinicians were using blood thinners as part of the treatment and getting success.

What we have understood is these micro clots need immediate retrieval in order to save the limbs, Dr Satwik added.

He also said it is very difficult to know the prevalence of clots in the entire population infected with COVID. Although it is difficult to determine the vulnerability of COVID-19, individuals with existing cardiovascular morbidities are the ones who will suffer thrombotic complications, Dr Satwik said.

According to Dr Kumar, in COVID-19 patients, the clots seem to form in the tiny vessels of the lungs rather than the major vessels, adding that clots in the lungs usually happen in the case of typical strokes or heart attacks or deep vein thrombosis.

Risk of COVID-19 patients associated with blood clots are stroke (clot in the cerebral artery), clots in the lungs, heart attack, deep vein thrombosis, and thrombosis in both upper and lower limb arteries. Stroke can cause paralysis, but we have not seen any such so far in our hospital, Dr Kumar added.

Also Read: Russia’s Single-Dose Sputnik Light Vaccine Has 79.4 Per Cent Efficacy, Effective Against All New Coronavirus Strains: Russian Direct Investment Fund

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

NDTV – Dettol Banega Swasth India campaign is an extension of the five-year-old Banega Swachh India initiative helmed by Campaign Ambassador Amitabh Bachchan. It aims to spread awareness about critical health issues facing the country. In wake of the current COVID-19 pandemic, the need for WASH (WaterSanitation and Hygiene) is reaffirmed as handwashing is one of the ways to prevent Coronavirus infection and other diseases. The campaign highlights the importance of nutrition and healthcare for women and children to prevent maternal and child mortality, fight malnutrition, stunting, wasting, anaemia and disease prevention through vaccines. Importance of programmes like Public Distribution System (PDS), Mid-day Meal Scheme, POSHAN Abhiyan and the role of Aganwadis and ASHA workers are also covered. Only a Swachh or clean India where toilets are used and open defecation free (ODF) status achieved as part of the Swachh Bharat Abhiyan launched by Prime Minister Narendra Modi in 2014, can eradicate diseases like diahorrea and become a Swasth or healthy India. The campaign will continue to cover issues like air pollutionwaste managementplastic banmanual scavenging and sanitation workers and menstrual hygiene


Coronavirus has spread to 196 countries. The total confirmed cases worldwide are 26,78,24,983 and 52,79,148 have died; 22,84,48,447 are active cases and 3,40,97,388 have recovered as on December 9, 2021 at 3:47 am.


3,46,66,241 9,419Cases
94,742 1,009Active
3,40,97,388 8,251Recovered
4,74,111 159Deaths
In India, there are 3,46,66,241 confirmed cases including 4,74,111 deaths. The number of active cases is 94,742 and 3,40,97,388 have recovered as on December 9, 2021 at 2:30 am.

State Details

State Cases Active Recovered Deaths

66,40,888 893

9,964 157

64,89,720 1,040

1,41,204 10


51,78,892 5,038

41,615 887

50,95,263 4,039

42,014 112


29,99,098 399

7,284 155

29,53,565 238

38,249 6

Tamil Nadu

27,32,648 703

7,946 36

26,88,142 728

36,560 11

Andhra Pradesh

20,74,217 181

2,011 3

20,57,749 176

14,457 2

Uttar Pradesh

17,10,502 10

139 7

16,87,452 3


West Bengal

16,20,803 574

7,576 0

15,93,659 568

19,568 6


14,41,514 65

404 28

14,16,010 36

25,100 1


10,50,760 255

1,931 11

10,40,403 264

8,426 2


10,07,075 37

341 9

9,93,140 27

13,594 1


9,54,984 40

236 16

9,45,792 24



8,27,873 67

417 45

8,17,361 22


Madhya Pradesh

7,93,288 14

140 1

7,82,619 13



7,71,904 29

223 15

7,61,626 14



7,26,259 9

36 6

7,14,133 3



6,77,546 205

3,871 19

6,69,673 185

4,002 1


6,18,042 134

2,541 24

6,09,374 158



6,03,578 22

350 0

5,86,614 20

16,614 2


3,49,383 16

129 7

3,44,113 23



3,44,402 17

192 3

3,36,799 14


Jammu And Kashmir

3,38,198 151

1,639 38

3,32,070 111

4,489 2

Himachal Pradesh

2,27,753 69

722 14

2,23,174 81

3,857 2


1,79,307 65

441 37

1,75,478 28



1,37,377 320

3,049 10

1,33,819 309

509 1


1,29,128 23

230 1

1,27,022 22



1,25,429 23

325 5

1,23,119 28



84,888 14

94 11

83,968 3



84,631 12

240 11

82,916 23



65,515 7

67 2

64,628 5


Arunachal Pradesh

55,298 3

29 2

54,989 5



32,390 8

200 2

31,785 6



32,143 1

116 2

31,328 3



21,749 14

230 17

21,304 31


Dadra And Nagar Haveli


0 0





11 0



Andaman And Nicobar Islands

7,691 1

3 0

7,559 1


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