Right and light ventricular dimensions as determinants of ventricular septal motion.

Echocardiographic studies were performed in 86 patients with right ventricular volume overload. In 45 of these 86 patients, 58 echocardiograms were performed at different intervals in the postoperative period. For control purposes, 60 normal subjects and 18 patients with right ventricular pressure overload were also examined. The right ventricular end-diastolic dimension (RVED) and the left ventricular end-diastolic dimension (LVED) were measured on the echocardiograms. The RVED/LVED ratio was significantly elevated in patients with right ventricular volume overload. In all groups, a RVED/LVED ratio above 0.65 was usually associated with an abnormal motion of the septum; and on this basis the subjects with abnormal septal motion could clearly be separated from those with normal motion. After surgery, significant reductions of the RVED/LVED ratio were observed in patients whose septal motion reverted to normal. The RVED/LVED ratio remained significantly higher, usually above 0.65, in patients with persistent abnormal septal motion. These findings suggest that the relative sizes of the right and left ventricular cavities are probably major determinants of ventricular septal motion. Abnormal motion may result from a change in the end-diastolic shape of the septum.