Washington (AFP)

After 18 days in intensive care in Los Angeles, doctors treating Canadian actor Nick Cordero, seriously ill with the new coronavirus, amputated his right leg. A permanent clot blocked the circulation of blood.

This is one of the dark discoveries of the pandemic: Covid-19 disease, initially perceived as a virulent respiratory condition, attacks much more than the lungs. We have already noticed that other organs, such as the kidneys, are affected.

Clots in blood vessels can suffocate the limbs. When they form in the veins of the leg (phlebitis), they can dislodge themselves and go up towards the lungs, block the artery there and put them at a stop (pulmonary embolism). In the heart, they can cause a heart attack. When they go to the brain, it's a stroke.

All of these scenarios have been observed in Covid-19 patients who had no risk factors other than having contracted the new coronavirus.

In his department at NYU Langone, Shari Brosnahan, a resuscitator specializing in the lungs, told AFP that it is still rare. But the number of cases where clots come up through the veins more than doubled during the pandemic in his critically ill patients.

The relative youth of some patients is a surprise.

Shari Brosnahan currently has two forties in intensive care, one of whom risks losing a hand and the other, all four members.

"The fingers can often develop dry gangrene," she explains.

Normally, against clots, blood thinners like heparin are given. But it does not always work and sometimes causes internal bleeding, as at Nick Cordero, according to his wife who informs her fans on Instagram.

"This clotting is not like regular clotting," says the doctor.

Many have "micro clots", she says, "down to the capillaries", which are the smallest blood vessels. Impossible in this case to operate, unlike large clots in a lung or brain. Amputation is then often the only possible end.

- A key or more? -

At the New York veterans hospital, Cecilia Mirant-Borde, a resuscitator for 25 years, says that almost all of the patients in her department are treated with anticoagulants, or even more dangerous drugs that destroy clots.

She explains to AFP that she has discovered countless micro clots in the lungs, which would clear up another Covid-19 mystery: why artificial respirators seem so ineffective. In fact, blood cannot circulate well in the lungs because of clots ... and leaves in the body without being oxygenated. There is nothing the respirator can do about it.

First in China, then in Europe, and now in the United States, doctors learn on the job and try to document the phenomenon.

"I have seen hundreds of clots in my career, but I have never seen so many extreme abnormal cases," Behnood Bikdeli, an internal medicine specialist at Columbia University Medical Center, told AFP.

He participated in an international collaboration of 36 experts who recently published their recommendations in the Journal of the American College of Cardiology.

The enigma remains: why this coagulation?

Perhaps this is due to the cardiovascular or pulmonary history of many patients, says the doctor. Perhaps the clots are a consequence of the inflammatory outbreak associated with the disease. "Any acute illness, in itself, predisposes to the creation of clots," says Behnood Bikdeli quite simply.

A final hypothesis is that the coronavirus acts directly on the coagulation.

But at this stage, nothing is proven.

Shari Brosnahan is only half surprised.

"Viruses often do strange things," says the doctor, noting that the mononucleosis virus (Epstein-Barr) has been linked to leukemia, or the HPV virus to cervical cancer. "We are just discovering the strange things that this virus produces".

The variety of complications of Covid-19 may seem confusing, but research on the underlying mechanism (s) has only been started for four months.

"It is possible that everything is caused by a single thing, and that a single solution exists", imagines Shari Brosnahan.

© 2020 AFP