Plain roentgenographic estimation of systolic pulmonary artery pressure by the pulmonary arterial angle method

Chest roentgenograms of 125 patients (115 with pure or predominant mitral stenosis) were studied by the pulmonary arterial angle method to estimate systolic pulmonary artery pressure without prior knowledge of catheterization data. First the angle between the line drawn along the right upper lobe artery and the tangent drawn along the point of junction of superior and lateral borders of the right pulmonary artery was determined. Next the angle between the right middle lobe artery and the descending pulmonary artery is determined. The difference between these angles equals systolic pulmonary artery pressure. Catheter and angle values were identical in 26 patients. There was a 1- to 5-mm difference in 70, a 6- to 10-mm difference in 18, an 11- to 15-mm difference in 8, and a difference greater than 15 mm in 3.