Estimation of right and left ventricular size by ultrasound: A study of the echoes from the interventricular septum

Abstract

A technic utilizing pulsed reflected ultrasound has been developed for estimating the size of both the right and left ventricles. The key to this technic is the recording of echoes from the interventricular septum. These echoes have been recognized previously but never have been described in any detail. With the septal echoes it is possible to obtain a right ventricular dimension between the echo originating from the anterior epicardial surface of the right ventricle to the right side of the interventricular septum. A left ventricular internal dimension is also obtainable between the left side of the septum and the echoes stemming from the endocardial surface of the posterior left ventricular wall. These ultrasound measurements were obtained during end-diastole in 26 normal subjects, 23 patients with atrial septal defects and large left to right shunts proved by cardiac catheterization and 12 patients with angiographically proved marked aortic or mitral regurgitation and dilated left ventricle. In the normal group the mean right ventricular dimension was 1.5 ± 0.4 cm. (range 0.5 to 2.1). The mean left ventricular dimension was 4.5 ± 0.5 cm. (range 3.5 to 5.3). The patients with the atrial septal defects had an increased mean right ventricular dimension of 3.7 ± 1.1 cm. (range 2.2 to 6.3), which differed significantly from the normal ( p < 0.001). The group with the dilated left ventricles had a normal right ventricular dimension but the mean left ventricular internal dimension was 6.9 ± 0.9 cm. (range 5.5 to 9.0). This measurement was significantly higher than in the normal group ( p < 0.001). These results are very promising and suggest that a qualitative and possibly quantitative estimate of right and left ventricular size is feasible using this technic. Besides facilitating measurements of the right and left ventricles, recognition of the interventricular septal echoes represents an important contribution to echocardiography because these echoes can be a source of confusion when examining for pericardial effusion or mitral stenosis. In addition, the location and motion of the interventricular septum introduces a new area of investigative and diagnostic possibilities for this increasingly popular technic.