A Pathophysiological Study of 10 Cases of Hypoxic Cor Pulmonale

SUMMARY A pathophysiological study of the pulmonary vasculature in 10patients with hypoxic cor pulmonale and severe airways obstruction(five treated and five untreated with long-term oxygen) is presented.The media of muscular pulmonary arteries was normal or atrophicbut, in the intima, there was active deposition of longitudinalmuscle, fibrosis and elastosis. In the arterioles a medial coatof circular smooth muscle bounded by a new internal elasticlamina had developed, while there was deposition of longitudinalmuscle and fibrosis in the intima. In five cases the lumen wassubdivided into parallel tubes, found by serial section to leadinto alveolar capillaries. These features are distinctive ofhypoxaemia and obstructive airways disease. Changes continueduntil death. The conspicuous longitudinal muscle may be attributableto stretching of vessels round distorted terminal airways; furtherexploration into mechanisms is required. The hypothesis thatvascular changes follow hypoxic vasoconstriction is no longertenable. No correlations were found between quantitative pathologicalfindings and arterial blood gas tensions, pulmonary artery pressureor haematocrit. There were no differences between patients treatedor not treated with oxygen which might suggest that it arrestspathological changes. Thus, once a patient is given oxygen,survival probably depends as much on progressive mechanicalchanges in the lung as on continuing hypoxaemia.