Figure 6b. Posteroanterior chest radiographs show subtle but physiologically important differences between normovolemic and oligemic cases, especially with regard to pulmonary BV, which can most easily be seen through the cardiac shadow. (a) Case 7. A patient with mixed AS and AI. The radiographic severity index is 1, the lungs are normovolemic, mild left ventricular enlargement is present, and the vascular pedicle is narrow (4.8 cm). Catheterization data include stroke volume of 90 mL, wedge pressure of 14 mm Hg, pulmonary arterial pressure of 19 mm Hg, and cardiac output of 5.5 L/min. (b) Case 1. A patient with AS. The radiographic severity grade is 5, the lungs are oligemic, mild biventricular enlargement is present, the vascular pedicle is narrow (4.6 cm), and the azygos vein is very small. Note also the convex main pulmonary artery (arrow). Catheterization data include stroke volume of 31 mL, wedge pressure of 27 mm Hg, pulmonary arterial pressure of 35 mm Hg, and cardiac output of 3.3 L/min.