EVALUATION OF LEFT VENTRICULAR ENLARGEMENT IN THE LATERAL PROJECTION OF THE CHEST.

Abstract

TEFT VENTRICULAR enlargement is probably the most frequent chamber enlargement in the adult heart, yet its detection is often difficult. According to Parkinson (3) the enlargement is more posterior than lateral in most patients. In all probability the left ventricle is enlarged in both directions in the majority of cases, but there are so many exceptions that roentgen studies in both posteroanterior and lateral views are commonly used. Eyler and his associates in 1959 (1) made an original and ingenious suggestion for the determination of left ventricular enlargement in the lateral view. They described an abnormal change in the relationship of the left ventricle to the inferior vena cava and the left leaf of the diaphragm. They noted that if the left ventricle extended posteriorly beyond the upper end of the vena cava more than 1.5 cm, it probably was a sign of left ventricular enlargement. It has been our experience, however, that the junction of the inferior vena cava and the right atrium is poorly defined in a great many cases. More recently, the incorporation of the shadow of the inferior vena cava into that of the left ventricle in the lateral view has been recommended as a sign of left ventricular enlargement, specifically for the differentiation of interatrial from interventricular septal defects (2). The determination of left ventricular enlargement is likewise of great importance in the differentiation of mitral stenosis from mitral insufficiency and for the estimation of the degree of aortic insufficiency associated with aortic stenosis. In a few cases the demonstration of enlargement of the left ventricle may be the most important diagnostic sign of cardiac disease. It is the purpose of this paper to define two measurements easily obtained from the lateral chest film and to determine their degree of efficacy in evaluating left ventricular size. Methods and Materials Figure 1 is a diagrammatic cross section of the heart at the level of the junction of the inferior vena cava and the posterior wall of the right atrium. It is apparent that enlargement of the left ventricle posteriorly will displace its posterior margin behind the inferior vena cava. If the right atrium enlarges posteriorly the inferior vena cava will move with it. The normal relationships of the inferior vena cava, left ventricle, and left leaf of the diaphragm on lateral view are shown in Figure 2. Injection of contrast material into the inferior vena cava (Fig. 3) demonstrates that the linear shadow seen on the lateral chest roentgenogram is in fact the posterior margin of the inferior vena cava. Measurement A is defined as the distance which the left ventricle extends posteriorly to the posterior border of the inferior vena cava at a point 2 em cephalad to the crossing of the cava and the left ventricle. This measurement is made on a plane extending posteriorly which parallels the horizontal plane of the vertebral bodies.