[Septal subaortic hypertrophy. Apropos of 23 cases]

Septal subaortic enlargement is seen by two-dimensional echography and involves localized hypertrophy of the basal part of the interventricular septum, the thickness of which is greater than or equal to 13 mm. The present study relates to 23 septal subaortic enlargements. Means thickness of the enlargement was 17.0 mm and the longitudinal parasternal length was 22.1 mm. SAM was noted in 2 cases and mesosytolic closure of the sigmoid sinuses in one case. Left ventricular volume was much reduced in one third of cases, especially when enlargement was great. Compliance disorders were marked in one third of cases. Only the longest and thickest enlargements caused obstruction, which was noted in 18% of cases. Enlargement was most often associated with valvular (56% of cases) or hypertensive (48 P of cases) pathologies. No specific clinical, radiologic or electrical signs were noted; anomalies were due to pathology associated with the enlargements. A stable trend was generally seen in subaortic hypertrophy after a mean period of 33 months. Nevertheless, moderate increases in hypertrophy were seen in 20% of cases. In the great majority of cases, enlargement did not correspond to obstructive hypertrophic cardiomyopathy according to Goodwin's criteria, and etiology remains uncertain due to lack of histological data.