The Angiocardiographic Measurement of the Normal Great Vessels

Since the early roentgenographic era, many methods have been employed to estimate the size of body structures by the measurement of their roentgen images. In cardiac roentgenography, distortion has been reduced to a minimum through the use of teleroentgenography. A comprehensive review of roentgenographic measurement of the heart has recently been made by Ungerleider (1). Measurement of the diameter of the aorta has been a controversial subject, and methods for its accomplishment have been many. All projections have been employed to delineate the ascending, transverse, and descending aorta. The width of the superior mediastinum in the frontal projection affords a poor estimate of the aortic diameter, as it may be widely altered by arteriosclerotic tortuosity or hypertensive unfolding of the aorta. The best aortic measurement in the frontal projection, that between the outermost point of the aortic knob and the barium-filled esophagus, is subject to variation in the thickness of the esophageal wall and of the tissues between it and the aorta. The method gives no impression of the thickness of the aortic wall. The customary left anterior oblique measurement, though occasionally satisfactory in the presence of arteriosclerotic or syphilitic calcification of the aorta, is generally misleading because of the difficulty in outlining the inner or inferior margin of the aorta (2). Many methods of determining the degree of enlargement of the pulmonary arterial tree suffer from the fact that the measurements are indirect (3). Standards have varied widely with the method used, and interpretation of figures has been difficult. The roentgen diagnosis of syphilitic aortitis has depended largely upon the intimal deposition of calcium in the aorta, often a late manifestation. The aorta in its ascending portion is indistinguishable from the cardiac shadow, and thus that portion of the vessel earliest affected in syphilitic disease is not demonstrated by conventional methods. Early pulmonary heart disease is not detected because of the failure of the conventional roentgenogram to afford accurate measurements of the pulmonary artery. With the advent of a practical method of angiocardiography in 1938 (4), measurements of the great vessels have become simple and reliable, and comparable results are obtained by independent observers. Not only may the caliber of the aorta and pulmonary artery, as well as of their branches, be measured, but often the thickness of the vessel wall may be clearly demonstrated. The Aorta One hundred normal aortas visualized angiocardiographically have been analyzed. The various projections were employed and were found to check within one or two millimeters of each other in a given case. Presumably, variations were based on the different distances between aorta and film in different projections, since the aorta is round in normal subjects.