SIZE, LOCATION, AND GRAVITATIONAL CHANGES OF NORMAL UPPER LOBE PULMONARY VEINS

In a previous study, the upper lobe pulmonary venous distention after exhaustive exercise was assessed in chest roentgenograms. The efficacy of evaluating upper lobe veins in future studies depended on several anatomic considerations.

Fifty venous angiocardiograms obtained in the recumbent position and 50 examinations performed in the sitting position were reviewed. The opacified pulmonary vessels were measured at main pulmonary artery and aortic arch levels. The level of vessel bifurcation and the vessel direction were tabulated. The relationship between artery and ipsilateral vein was noted. Comparison of vein size in the recumbent and sitting positions was made.

The upper lobe pulmonary veins are most consistently visualized at the main pulmonary artery level. Superimposition of artery and vein occurs in 40 to 50 per cent of examinations; otherwise, the vein is almost invariably lateral to the artery. The pulmonary vessels are most likely vertical in the left upper lobe and either vertical or oblique in the right upper lobe. The upper lobe veins vary considerably in diameter, and bifurcate below the aortic arch level in 40 per cent of the examinations. Significant gravitational changes in normal pulmonary vein diameters occur.

Although the normal upper lobe pulmonary veins are usually too small to identify, detection of upper lobe pulmonary veins on a chest roentgenogram does not necessarily indicate pulmonary venous hypertension or flow redistribution. However, considerable significance can be ascribed to the initial detection or to the diameter change of the pulmonary veins in serial chest roentgenograms. The failure to consistently identify upper lobe veins in patients known to have pulmonary venous hypertension is probably related to the frequency of superimposition of the artery and vein.

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