When the blood thickens – Treating arterial thrombosis in COVID-19 patients

Various studies have confirmed an increased risk of arterial thrombosis in COVID-19 patients. If left untreated, these clots can compromise the blood circulation to the limb leading to gangrene and amputation as the only choice. Dr Raghuram Sekhar, consultant, vascular and endovascular surgery, Kokilaben Dhirubhai Ambani Hospital and Medical Research Institute shares his experiences with treating arterial thrombosis in 20 COVID-19 patients at KDAH

 As doctors and researchers learn more about COVID-19, they are discovering newer complications that the SARS-CoV-2 virus can bring about. While the primary area of attack is the respiratory system and the disease in the initial part of the pandemic was thought to mainly affect the lungs and present as a viral pneumonia, it is now recognised that the novel coronavirus can impact organs throughout the body.

COVID-19 has a significant impact on the cardiovascular system with the infection leading to various cardiovascular syndromes such as acute coronary syndrome, cardiac arrhythmias, and myocardial damage. One other complication of the cardiovascular system that can lead to long-term morbidity and disability arises from COVID-19 causing hypercoagulability, that is, increasing the tendency of blood to thrombose or clot. This increased risk of forming blood clots in the circulatory system has also been seen earlier in the other coronavirus diseases – SARS and MERS.

While the fact that this can lead to venous thromboembolism and pulmonary embolism, with consequent right ventricular dysfunction or failure is known, the alarming rise in occurrence of clots in arteries of the limbs is something vascular surgeons are encountering with increasing regularity. These clots are not always fatal and are very much manageable and curable provided the patient comes in time. These are however not ordinary clots and it is necessary for both the doctor and the patient to understand this. The clots occur in the extremities and may form in the upper and lower limbs (arms and legs).

There is a particular mechanism why these clots form and the nature of the clot is way different. The cause of the hypercoagulability can be traced to hypoxia or low oxygen levels in COVID-19 making the blood thicker or more viscous and stimulating thrombosis or clotting in the circulatory system. Hypercoagulability can also result from abnormal functioning of the endothelial cells that line the interior surface of blood vessels. The virus attacking blood vessel cells causes inflammation, excess generation of thrombin and formation of clots, big and small.

Various studies have confirmed this increased risk of arterial thrombosis in COVID-19 patients. If left untreated, these clots can compromise the blood circulation to the limb leading to gangrene and amputation as the only choice.

It is important to take a different approach with counselling of the patient at an early stage. Treating clots in COVID positive patients might not be as linear as say an appendicitis operation. While like any surgical emergency, earlier done, the better are the treatment outcome and result, choice of options in therapy and exercising them appropriately and judiciously is paramount to outcomes.

At Kokilaben Dhirubhai Ambani Hospital, we have treated around 20 patients with clots in their peripheral arteries. These COVID-19 patients had co-morbidities but their co-existing chronic condition such as diabetes or hypertension was stable with regular treatment and a disciplined medication routine. In three of the cases, the patient’s RT-PCR was negative but their CT scans indicated COVID-19 infection. The false negative swab test, with CT scan showing a classic picture has now been documented in COVID literature, and is one of the limitations of the RT-PCR test. This is critical as the limitations of the RT-PCR should not lull the treating doctor and patient into a false sense of security and the delay action in treating the blood clots.

This is an interesting trend that is seen, but definitely needs more cases and research to substantiate further. Our experiences with a large number of cases has enabled us to put a protocol in place to treat patients suspected of arterial thrombosis. Our experience has been positive and we have had very good results in the cases that were treated early.

When to treat and how to treat

It is important to decide when to treat and how to treat. If there is a negative RT-PCR and patients have these clots, the CT scan must be checked for lesions in the lungs. The symptoms may be in the form of mild cold, cough, and fever but CT scan will show lesions. Laboratory tests such as D-dimers, prothrombin time, and platelet count, can help in identifying patients at increased risk of blood clot formation. Anticoagulant therapy has been associated with lower mortality in patients.

Patients may not take cognizance of these mild symptoms that indicate onset of infectivity but at the beginning of the second week, they develop clots. In most cases, we have seen clots begin to develop at the end of the first week and beginning of the second week. This is a time when we are probably lowering our guard, thinking the worst is over. This leads to many patients going home without being treated with a blood thinning agent, and in 10-12 days they have numbness, tingling in the affected limb/s and massive clots that are difficult to treat with traditional method such as putting a catheter and then bursting or dissolving them with clot dissolving agents, and require open vascular surgery. In extreme cases, they present with excruciating pain in the affected limb with difficulty in movement of the limb.

The clots found in COVID are very sticky, hard and bulky and in addition to treatment through catheters using chemical to dissolve the clot, we have performed open vascular surgery to remove the clots physically and even bypass surgery to maintain circulation. Patients’ symptoms at presentation vary from numbness in hands/feet to severe pain in muscles of affected limb. Change in color of the skin of the affected limb to blue / black, or loss of movement of the toes/fingers is an ominous sign

The cases successfully treated at KDAH include 11 patients who came with very sticky clots where open vascular surgery was performed to scrape the clot out of the blood vessel and restore circulation to the affected limb.

Four cases presented in the first  week of positivity and were subjected to endovascular therapy using catheter directed clot dissolving drugs and suction of clots of which one had to be converted to open vascular surgery. All four cases were thus successfully salvaged. Five patients unfortunately came late and were advised major amputation of the limb, two of whom lost both lower limbs.

The hypercoagulability in COVID infections can also lead to clots being formed in the vessels supplying the heart and the brain leading to a heart attack and/or a stroke. Therefore, it is important that even after the vascular surgery, patients should continue to take blood-thinning tablets for an extended period, undergo regular physiotherapy and follow up with the doctor regularly.

We now have appropriate protocols in place for COVID related arterial thrombosis. All COVID patients are rigorously and repeated screened for early evidence of arterial thrombosis. While anticoagulation with blood thinners remains the mainstay, even after discharge of the patient home, appropriate surgery gives rewarding results when performed timely. Endovascular catheter directed therapy for chemically dissolving clots and thrombosuction is best in the first week of diagnosis of florid CCOVID infection, when the limb is immediately threatened and waiting is not an option.

COVID-19 has thrown many surprises, but as our experience with 20 patients shows, if we are prepared and implement proper treatment in time, we can save lives and limbs!