Pulmonary hypertension associated with COPD

Abstract

Although the prevalence of pulmonary hypertension (PH) in individuals with chronic obstructive pulmonary disease (COPD) is not known precisely, approximately 10%-30% of patients with moderate to severe COPD have elevated pulmonary pressures. The vast majority of PH associated with COPD is mild to moderate and severe PH occurs in < 5% of patients. When COPD is associated with PH, both mortality and morbidity are increased. There are no clinical or physical examination findings that accurately identify patients with underlying PH. Radiographic imaging findings are specific but not sensitive indicators of PH. Echocardiography is the principle noninvasive diagnostic test but may be technically limited in a significant proportion of patients with COPD. Right heart catheterization is required for accurate measurement of pulmonary pressures. The combined effects of inflammation, endothelial cell dysfunction, and angiogenesis appear to contribute to the development of PH associated with COPD. Systemic vasodilators have not been found to be effective therapy. Selective pulmonary vasodilators including inhaled nitric oxide and phosphodiesterase inhibitors are promising treatments for patients with COPD associated PH but further evaluation of these medications is needed prior to their routine use.

Figure 1

Histologic evidence of vascular changes in a small pulmonary artery in a patient with COPD and associated pulmonary hypertension. Hematoxylin and eosin staining demonstrates marked medial and intimal thickening with resulting luminal narrowing (40X, original magnification). Photomicrograph was provided courtesy of Hai Bui, MD, Department of Pathology, Cincinnati VAMC, Cincinnati Ohio.

Figure 2

Pathophysiology of PH and right ventricular dysfunction associated with COPD. The combined action of hypoxemia, toxic tobacco smoke, pulmonary dysfunction, and polycythemia lead to endothelial dysfunction, growth factor production, and inflammation in the pulmonary vasculature. These processes cause elevation of pulmonary arterial pressures. PH may cause RV hypertrophy and subsequent RV contractile dysfunction and RV failure.

Figure 3

A. Posterior-anterior chest X-ray and B. Lateral chest X-ray demonstrating enlarged pulmonary arteries and severe hyperinflation. The metallic opacification is a left nipple ring. C. Chest CT scan at the level of the pulmonary outflow tract demonstrating a main pulmonary artery diameter greater than the adjacent aorta. D. Chest CT scan at the level of the lower lobes demonstrating segmental pulmonary arteries that are larger than the accompanying bronchi. E. Chest CT at the same level as Figure 3C using parenchymal windows to demonstrate severe emphysematous changes throughout the lung parenchyma.