[Changes of the liver blood vessels in the pulmonary trunk stenosis at compensation and decompensation]

Changes of liver blood vessel structure were studied in 23 pups with the model of compensated pulmonary trunk stenosis and in 8 animals with decompensated stenosis during 6-24 months after the establishment of stenosis. The liver of 10 age-matched dogs was used as a control. Material was studied using histological, morphometric and stereometric methods. It was found that after the establishment of pulmonary trunk stenosis and compromise to venous blood outflow from the liver, the tone of the arteries increased as well as the resistance to the blood flow. Besides the venous-arterial reaction, the bundles of oblique-longitudinal smooth muscle cells and musculo-elastic sphincters were shown to be formed in the intima of the afferent vessels, while in the efferent vessels the hypertrophy of the muscular folds took place. In decompensated stenosis, the hypoxia was combined with the relaxation of the walls of both afferent and efferent vessels, the number of arteries with the adaptational structures was decreased, while the muscular folds of hepatic veins underwent atrophy. The failure of adaptation mechanisms resulted in the development of chronic liver venous congestion.