Haemodynamic and pathological study of the effect of chronic hypoxia and subsequent recovery of the heart and pulmonary vasculature of the rat.

Abstract

It is shown that when rats are exposed to chronic hypoxia in a decompression chamber they develop an increase in right ventricular mean pressure, right ventricular hypertrophy, and a characteristic form of hypertensive pulmonary vascular disease. The pulmonary vascular lesions consist of muscularization of the pulmonary arterioles, accompanied in a proportion of rats by medial thickening of the smaller muscular pulmonary arteries. When the animals are removed from the hypoxic environment, there is a progressive reduction of the right ventricular pressure and a regression of the pulmonary vascular disease. The results show that in rats the pulmonary hypertension and associated pulmonary vascular disease induced by chronic hypoxia are reversible. The findings support the hypothesis that the organic basis for the pulmonary hypertension in human subjects with chronic hypoxia is a muscularization of the small pulmonary arterial vessels, and that removal of the hypoxia produces regression of the pulmonary vascular changes and associated pulmonary hypertension.