Covid-19 infection and blood clots: How to prevent, identify and treat?

Dr. Santosh B. Patil

The ongoing global pandemic of coronavirus disease 2019 (COVID-19) may cause, in addition to lung disease, a wide range of non-respiratory complications. Among these, thromboembolic complications due to abnormal clotting of blood in the arteries as well as veins present as an important issue and may occur in up to 30% of COVID-19 patients in the intensive care unit (ICU). These complications are found to occur during the period of actual illness as well as during the recovery period following the illness. It's unclear exactly how COVID-19 leads to blood clots. However, the infection has been found to activate various cells and molecules in the body that are involved in the clotting process. Blood clots can develop in various organ systems of the body and presentation can vary depending on the organ system involved.

1)Blood clots in arteries of legs/arms:

The formation of blood clots in the arteries of the legs or arms can result in acute ischemia (leg/arm attack). Symptoms can include sudden onset pain in the legs/arms, cold limbs, skin discoloration, absent pulse, loss of movement/sensation and blackening of the toes/fingers. A CT angiogram can confirm the diagnosis and give an idea about the extent of blockages.

2) Deep venous thrombosis:

Thrombosis of the deep veins of the legs is a common occurrence in Covid-19 infected patients and presents as swelling, pain and skin discoloration of the legs. USG Colour Doppler test confirms the diagnosis of DVT. A CT venogram may be advised to look for the proximal extent of the clots.

3) Blood clots in the lung arteries:

Blood clots in the arteries of the lungs, known as pulmonary thromboembolism, present as severe chest pain, increased difficulty in breathing and decreased oxygen saturation. CT pulmonary angiogram can confirm the diagnosis of pulmonary thromboembolism. Patients with DVT are more prone to develop pulmonary embolism as a clot from the veins of the legs can break off and travel to the arteries of the lungs.

4) Stroke:

Stroke in Covid-19 patients can happen due to the formation of blood clots in the arteries supplying the brain or in the veins draining blood from the brain. Patients present with various symptoms such as weakness of arms and legs, slurring of speech, facial weakness, giddiness, imbalance and loss of consciousness. CT/MRI brain with angiogram/venogram helps to identify the brain damage and the blockages in the vessels of the brain.

5) Heart attack:

COVID-19-related inflammation raises the risk of heart attack by activating the body's clotting system and disrupting the blood vessel lining, thereby causing blockages in the arteries of the heart. Burning or tightening in the chest radiating to the arms and neck, sharp, stabbing chest pain, unusual shortness of breath are some of the symptoms of a heart attack. Timely diagnosis and intervention by a cardiologist are needed in these patients.

6) Blood clots in the intestinal arteries:

Blood clots in the arteries supplying the intestines cause acute bowel ischemia. Symptoms include severe abdominal pain, vomiting, diarrhoea/constipation and blood in stools. CT angiogram of the abdomen helps to identify the clots in the intestinal arteries.

7) Blood clots in the renal vessels:

Thrombosis of the renal arteries can cause sudden onset flank pain, acute renal failure and decreased urine output. Blood clots can also develop in the renal veins, which can present as loin pain, vomiting, hematuria and decreased urine output. A contrast-enhanced CT scan identifies these blood clots and helps in treatment planning.

How to Prevent:

Guidelines suggest prophylaxis with blood-thinning agents for all hospitalized patients with COVID-19 in the absence of contraindications, such as active bleeding. These blood thinners can be continued during the recovery period in patients with a high risk of developing clotting complications.

Treatment options:

Therapeutic anticoagulation with blood-thinning agents forms the mainstay of treatment of clotting complications. If these complications are identified early, a vascular specialist doctor can perform certain procedures to remove the blood clots. A vascular interventional radiologist can offer mechanical thrombectomy / intra-arterial thrombolysis, which are minimally invasive procedures performed through a pinhole. These procedures rapidly clear the fresh thrombus and give early symptom relief as well as prevent long-term complications. Timely interventions in these patients can be lifesaving and help to reduce mortality and morbidity significantly.