Radiography of the Child's Heart.—While the radioscopic pic ture of the heart of older children shows no deviations from that of adults, the shadow of the heart in infancy and early childhood offers especial peculiarities on account of the proximity of the heart to the thymus gland and to the high potion of the diaphragm.
In normal infants almost the same picture is seen in radiograms of the thorax, as well in adventral as in addorsal projection; flanked on either side by bright areas corresponding to the lungs, with shadows of the ribs passing horizontally across them, a central shadow is noted, narrow above, Wide below, corresponding to the heart The lower portion of the shadow spreads out more to the left than to the right; the left and right ventricles. The outline of the upper part runs parallel to that of the vertebral column or is somewhat concave, spreading a little to each side of the shadow of the vertebral colunm.
This shadow which begins at the first OF second dorsal vertebra in the radi ograms, follows the upper chest ver tehrre and at the fourth, fifth, or sixth dorsal vertebra spreads out gradually, forming concave outlines asymmetri cally downward, which surround the convex outlines of the ventrieles of the heart. It must be noted that, in early childhood, the small upper portion of the central shadow must be due chiefly to the thymus gland, for the thymus, as is well known, surrounds the large vessels at their exit from the heart-sac, so that the large blood vessels can be imagined in the middle of this shadow. This differs from the radiogram of the adult thorax, in which the outlines of the upper portion of the central shadow are formed by the vena cave, and pulmonary aorta. Besides, here also the large blood vessels cause but a small dark zone in the Rontgen picture, passing a little laterally beyond the shadow of the vertebral column, and spreading beyond the shadow of the ver tebral colutnn only when dilatation of the vessels occur.
Rantgen examination of the normal infant's thorax shows a central shadow, in shape like a flask with a bulMng body and narrow neck. The cervical portion of this flask-shaped central shadow extends from the first or second to the fifth or sixth dorsal vertebra. Its lateral lines just approximate those of the shadows of the vertebne (Fig, SO). As we commonly find this pirture in normal children entirely with out symptoms, in whoni the dulness caused by the thymus gland does not extend beyond the edges of the .ternitin, it. should be considered
the normal shadow-picture of the young child, corresponding to both thymus gland and large vessels above, while the body of this flask shaped shadow belongs to the. mass of the heart.
By means of radioscopy the position of the apex. the size of the heart and its motility can be establlshed in the shadows projected. By fixing the position of the nipples, the relations of the edges of thc heart to the rnammillary line are easily noted.
In order to prevent errors in estimating the relations of size and position of the pictures of Hie thorax in the Rontgen prints viewed, attention must be directed to the fact that only radiograms should be considered in which the tubes have been set up above the child in the median line, and at some distance from the child (in small children 50 em. from focus to plate; in larger children, 60 to SO cm., Kienbock).
Hochsinger's investigations have shown that exact estimations of the cardiac dulness have always agreed with the shadow of the heart in the Rontgen pictures. Radiography has proved invaluable in childhood for exactly estimating the position of the heart. Thus congenital median position of the heart is recognized at the first glance. The rela tions in the size of both sides of the heart are shown in an extraordinary manner. But radiography is most important in the diagnosis of (Hata tion of the pulmonary artery due to persistent ductus Botalli, of aneurysm of the aorta and pulnionary artery, and also in the cliagnosis of pulmonary stenosis (see further on).
A means of differentiating whether the dilated pulmonary artery receives blood only from the right ventricle or also from a patulous duetus Botalli depends, according to de la Camp, on the nature of the pulsation of the shaded portion of the Itontgen picture. When a patu lous ductus Botalli persists, a systolic pttlsation, simultaneous with that of the areh of the aorta, but far more diffuse, occurs. As regards the shadows of the other blood vessels Ole upper arches of thc heart shad ow, Fig. 100) it should be noted that information upon the position and size of the arch of the aorta, its regular origin and course, can be ob tained; from dilatation and visible pulsation of the right upper shadow arch, dilatation or irregular origin of the aorta can be determined.