Mechanisms of Pulmonary Vascular Changes - Chronic Obstructive Pulmonary Disease - page 464

II. PULMONARY VASCULAR REMODELING IN COPD

In addition to alterations in vascular tone, vessels can undergo profound
fibrocellular changes that lead to an enlargement of the vessel wall; an active
process broadly defined as vascular remodeling. In the pulmonary vascular
bed, remodeling affects preferentially small and precapillary arteries and is
the principal pathological feature of pulmonary hypertension. Morphological
changes in pulmonary arteries have been identified at different degrees of
COPD severity.

A. Mild-to-Moderate COPD

Morphological characteristics of pulmonary muscular arteries in patients
with mild-to-moderate COPD have been assessed in lung specimens
obtained by surgical resection of lung carcinoma. These specimens provide
information on the early changes occurring in patients with a mild degree of
lung function impairment, since the patients must tolerate the resection of a
lung or lobe. These cases provide the opportunity to establish correlations
between functional measurements performed before surgery and structural
changes assessed in resected specimens.
Morphometric studies of pulmonary vessels in these patients have con-
sistently shown an enlargement of the intimal layer, with reduction of the

Figure 1 Morphometric measurements in pulmonary muscular arteries of nonsmo-
kers (white bars), smokers with normal lung function (dashed), patients with mild
COPD (gray) and patients with severe emphysema (black). Bars indicate mean values
of the proportion of total arterial surface occupied by muscularis, intima, and lumen.
p < 0.05 compared with nonsmokers; # p < 0.05 compared with smokers; y p < 0.05

compared with mild COPD.