Perivascular fibrosis of muscular pulmonary arteries in chronic obstructive pulmonary disease.

We performed a morphometric analysis of peribronchiolar and perivascular fibrosis in lungs obtained at autopsy from six patients with chronic bronchitis, six with pulmonary emphysema, and four normal control subjects. The areas of fibrosis outside the smooth muscle layer of bronchioles and outside the external elastic lamina of muscular pulmonary arteries were measured and their thickness was then calculated by assuming a round airway or artery. Patients with chronic bronchitis had significantly thicker peribronchiolar fibrosis in bronchioles of 1 mm or less in diameter and also thicker perivascular fibrosis of the adjacent muscular pulmonary arteries than the other two groups. The extent of perivascular fibrosis was significantly correlated with peribronchiolar fibrosis only in the muscular pulmonary arteries adjacent to the bronchioles but not in those away from the bronchioles. These findings suggest direct extension of chronic inflammation from bronchioles to the adjacent muscular pulmonary arteries in chronic bronchitis but not in pulmonary emphysema. Such perivascular fibrosis might lead to sustained pulmonary hypertension.