A critical evaluation of the roentgen criteria of right ventricular enlargement.

We believe that right ventricular enlargement is "over-diagnosed" radiologically, and this becomes apparent when radiologic interpretation is attempted without the help of other data. We tested this impression in a study of 25 cases of tetralogy of Fallot and 40 cases of other types of congenital pulmonary stenosis. In these cases there was usually no right ventricular dilatation. The roentgen determination of right ventricular hypertrophy was found to be decidedly of limited value. There were few infants in the present study and the conclusion should not be construed as necessarily including this group. HE commonly accepted roentgen criteria of right ventricular enlargement are: 1. Enlargement of the outflow tract anteriorly with bulging into the lung-filled triangle of the anterior mediastinum, seen earliest in the right anterior oblique position. 2. Enlargement in the posteroanterior position usually upward and to the left, resulting in filling of the con-cavity in the left border between the knob of the aorta and the left ventricle. 3. In the left anterior oblique position, anteriorly, there is a bulge of the lower portion of the contour. An angulation may be observed at the upper end of this bulge. The diaphragmatic portion of the heart increases in length with displacement of the interventricular groove posteriorly, then upwards, on the lower contour.1 These criteria have, in general, been derived from postmortem comparisons and, in addition , such animal experiments as those of Nemet who applied metallic markers to the interventricular septum. Since the advent of angiocardiography, doubt has been cast on these criteria. Thus it has been pointed out that, in the left oblique position, it is the right atrium that presents on the right contour in most cases and not the right ventricle; furthermore that the indentation seen radiologically in the left oblique position and called the interventricular groove does not regularly correspond to the position of the interventric-ular septum.2 Moreover, in the posteroanterior view, the pulmonary conus (defined as the subvalvular portion of the right ventricle) does not ordinarily approach the left contour. 391 Early observers such as Assmann recognized this from anatomic studies. In the right oblique position, the differentiation of pulmonary conus and artery is difficult; the precise limits of the conus inferiorly are even more difficult to establish. We have felt, therefore, that the conventional criteria of right ventricular enlargement measure, most often, changes in the right atrium and pulmonary artery, either primary or …