You are shown a posteroanterior (PA) and lateral chest radiograph of a 75-year-old woman. What is the MOST likely diagnosis?

The radiograph shows marked enlargement of the central pulmonary aeries with abrupt tapering, or pruning. This finding is consistent with pulmonary aerial hypeension. Although patients with atrial septal defect can develop pulmonary aerial hypeension, in this case, the lungs are markedly hyperinflated consistent with emphysema. In addition, the central pulmonary aeries are typically more markedly enlarged in patients with Eisenmenger physiology. Although chronic pulmonary emboli can result in pulmonary aerial hypeension, the lung volume would not be affected. The hyperinflation of the lungs in this case represents emphysema as the cause of the pulmonary aerial hypeension. Pulmonary venous hypeension occurs when the left ventricle is unable to pump the volume of blood that it receives. This results in elevated left atrial pressures and pulmonary venous hypeension. On chest radiographs, the findings of pulmonary venous hypeension include cephalization of the vasculature and enlargement of the vessels, interstitial and alveolar edema - findings that are not present in this case. The radiograph shows marked enlargement of the central pulmonary aeries with abrupt tapering, or pruning, consistent with pulmonary aerial hypeension. In addition, there is marked hyperinflation of the lung with diminished lung markings, consistent with emphysema. In severe cases of emphysema, there is obliteration of the capillary bed. If the volume of affected lung is large enough, pulmonary aerial hypeension will occur.