Deaths in the Covid-19 pandemic were not only caused by acute respiratory failure, but also microthrombosis of small vessels, associated with severe damage to organs other than the lung, such as the heart and kidneys, were found. This is the conclusion reached by a study coordinated by the University of Padua and conducted by a team of researchers from the Universities of Yale (USA) and Birmingham (UK), and the University Hospitals of Padua, Papa Giovanni XXIII (Bergamo), Asst Bergamo Est Seriate, and Fatebenefratelli Sacco (Milan), published in the Journal of Hepatology.
Although the main cause of mortality from Covid-19 had been attributed to hypoxic respiratory failure from acute respiratory distress syndrome (ARDS), small vessel thrombosis (microthrombosis) associated with severe functional impairment in multiple organs in addition to the lung, such as the heart and kidney, has been reported. Microthrombosis has also been observed in the liver, and although liver involvement was often present in patients with Covid-19, the significance of these alterations remained uncertain. Co-author of the study is Paolo Simioni, director of the Department of Medicine in Padua and of the Clinica Medica prima.
“At the cellular level – he explains – our study has shown that portal vein microthrombosis is supported by a response induced by Sars-CoV-2 infection that affects a type of vascular cell that is still very neglected, called ‘pericyte’, on the outside of the vessel, where it forms a lining sheath around the endothelium, the layer of cells that is in direct contact with the blood flow. This type of cell, once infected, activates the vascular secretion of coagulation mediators, including Tissue Factor and von Willebrand Factor, responsible on the one hand for the state of local hypercoagulability, with consequent thrombosis, and on the other for the dilation of the small pulmonary arteries with consequent reduction in oxygen saturation in the arterial blood”.
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