The effect of pulmonary hypertension on the elastic structure of the pulmonary trunk.

Microscopic studies of the pulmonary trunk in pulmonary hypertension of 28 cases and control groups of 65 cases ranging from the age of 1 to 83 years were carried out.The elastic configuration of the media of the pulmonary trunk was classified into 5 types and relationship between the severity of the pulmonary hypertension and changes of the elastic fibers in the media was carefully studied.As a result, increase of the elastic fibers even in the acquired severe pulmonary hypertension was observed.This finding is compatible to the views of Meyer although the methods of observation differ and is contradictory to the conclusions of Heath and Saldaiia.Marked changes of the elastic fibers in the media of pulmonary trunk was not found in dogs injected with lycopodeum spores, which may be due to the short duration of pressure loading.A close relationship of the elastic fibers with the smooth muscle cells was observed in the electron microscopic studies of animal experiments.