Pulmonary vascular changes begin early during the course of the disease .
Initially, these changes are characterised by thickening of the vessel wall and endothelial dysfunction .
These are followed by increased vascular smooth muscle and infiltration of the vessel wall by inflammatory cells, including macrophages and CD8+ T lymphocytes .
In advanced stages of the disease, there is collagen deposition and emphysematous destruction of the capillary bed . Eventually, these structural changes lead to pulmonary hypertension and right ventricular dysfunction (cor pulmonale) .
Fig. 4. - Pulmonary muscular artery from a patient with chronic obstructive pulmonary disease, showing prominent intimal thickening and luminal narrowing. a) Immunostaining with monoclonal antibody against a-smooth muscle actin, showing abundant proliferation of smooth muscle cells in the intima. b) Orcein stain showing abundant deposition of elastic fibres in the intimallayer. Internal scale bar=42.2 mm.