Q. Pulmonary Arterial System Changes ?

a) Pulmonary Plethora

With increased pulmonary arterial blood flow, pulmonary branches are visualized beyond the inner 2/3 of the lungs. Vessels in upper and lower lobes are dilated to the same degree. The number of end on vessels seen is 5 or more in both lung fields (or 3 or more in one lung field).

b) Pulmonary Arterial Hypertension

The features of pulmonary arterial hypertension are:

i) Central arterial enlargement, manifesting as an increased convexity of the pulmonary conus.

ii) Enlarged descending pulmonary artery, of more than 16 mm. Right descending arterial calibre of more than 25 mm is in keeping with Primary Pulmonary Hypertension.

iii) Sharp pruning of peripheral vasculature.

iv) Features of right ventricular hypertrophy and dilatation.

c) Pulmonary Oligemia

With reduced pulmonary flow, pulmonary vascular markings are markedly reduced, with vessels appearing attenuated. This is diagnosed radiographically only in patients with markedly decreased pulmonary flow.