Discrete subaortic stenosis: an acquired heart disease.

OBJECTIVE

To determine the anatomic variables in the left ventricular outflow tract in patients with subaortic stenosis.

METHODS

Between 1982 and 1996, 36 patients were operated on with the 'discrete' form of subaortic stenosis (DSS). The mean time of follow up was 7.4 years with a range of 4 months-14 years. There were 25 male and 11 female patients. Mean age at operation was 7.1 years with a range of 9 months-47 years.

RESULTS

At the time of surgery, the mitral valve apparatus and interventricular septum were found to be rotated 60-90 degrees in a counterclockwise fashion with anterior displacement into the left ventricular outflow tract in 30 (83%) patients. Subaortic ridge resection with a deep septal myectomy was performed in 32 patients and the remaining four patients had subaortic ridge resection alone. The reoperation free rate at 5 and 10 years were 74+/-9% and 60+/-12%, respectively. Reoperations for recurrent disease were performed in 10 (27.7%) patients. No operative or late follow up deaths were encountered.

CONCLUSION

We conclude that DSS is an acquired disease due to a pre-existing anatomic alteration in the mitral valve apparatus and interventricular septum. In addition, recurrence rates are high and physicians should not be mislead by the benign nomenclature its name implies.