Echocardiographic Study of the Ventricular Septal Defect with Subaortic Ridge

ABSTRACT

PURPOSE: The easy recognition and characterization of a discrete or fixed subaortic ridge by echocardiography provides a method for prospective study of the coexistence of ventricular septal defect (VSD) and subaortic ridge. In the presence of a VSD, a subaortic ridge may be clinically silent, but the obstruction can progress if the VSD is surgically or spontaneously closed. This study was carried out to test the hypothesis that the presence of a subaortic ridge associated with a VSD is related abnormal shunt flow through the septal defect. METHODS: Serial two-dimensional echocardiographic diagnosis of the coexistence of VSD and subaortic ridge was done prospectively in 271 patients. The VSD was morphologically characterized as perimembranous, muscular, or subarterial according to the components of its borders. Also, defect size of the VSD was characterized. The presence of septal malalignment was established when the outlet septum was deviated anteriorly or posteriorly. The subaortic ridge was recognized when an echo-bright localized protusion into the left ventricular outflow tract extending from the margin of the septal defect. RESULTS: The prevalence of a subaortic ridge was 8.86% (24/271). The mean age of patients at the initial detection of a subaortic ridge was 11.3+/-9.8 months. Among the 24 patients with a subaortic ridge 14 patients (p<0.01) had more than moderate defect in size of VSD. 16 patients (16/24) had malalignment VSD (p<0.01). A subaortic ridge was found in 20 (9.9%) patients with perimembranous VSD, 4 (8.3%) with subarterial VSD. CONCLUSIONS: The presence of a subaortic ridge associated with a VSD is related to a more than moderate sized defect and/or a malaligned ventricular septum. It is possible that the increased turbulence adjustance to the area of the VSD could favor the development of an abnormal fibrous tissue below the aortic valve.