Morphofunctional characteristics of the vessels of the small circle of blood circulation in those who died from severe and extremely severe forms of new coronavirus infection

Abstract

BACKGROUND: An important feature of COVID-19 is the development of pronounced hypercoagulation with an increased risk of thrombotic damage to the pulmonary vascular bed, mainly the pulmonary arteries. Thrombosis of the pulmonary blood vessels causes a local violation of hemodynamics with the development of hyperemia, edema, which leads to a decrease in ventilation of the lung tissue area and serves as one of the causes of respiratory failure. AIM: This study aimed to conduct a morphological and morphometric analysis of the vascular bed of lung tissues in deceased with severe and extremely severe forms of new coronavirus infection who were on inpatient treatment in the period 2020–2022. MATERIALS AND METHODS: A pathomorphologic study of 129 autopsy cases with a confirmed diagnosis of a new coronavirus infection COVID-19 was performed. Morphometric analysis and statistical data processing of the pulmonary vascular system in histologic preparations stained with hematoxylin and eosin stain, orcein stain and Martius Scarlet Blue (MSB) stain was performed. The control group consisted of 14 patients who died of cardiovascular disease with bilateral focal confluent pneumonia. RESULTS: It was found that the proportion of thrombosed vessels in the lung tissues of the deceased was 27.6%. In 87.2% of cases, thrombosis develops in small arteries (lumen diameter 30-500 microns) and small veins (lumen diameter 40–500 microns). The vascular-functional indices of Kernogan and Vogenworth were statistically significantly increased in small arteries and small veins of the 4th order (p=0.001), small arteries (p=0.001) and small veins of the 5th order (p=0.014) compared with the control group. CONCLUSIONS: Diffuse involvement of small caliber blood vessels in the pathological process reflects the severity of specific hemocoagulopathic disorders in the lung tissue. Such disorders lead to the development of ventilation-perfusion disorders and entail an increase in right ventricular failure.