Natural history of discrete subvalvar aortic stenosis: management implications.

Discrete subvalvar aortic stenosis (DSVAS) represents a unique cardiac lesion. As compared to most other congenital heart defects, DSVAS is virtually never recognized in early infancy, but appears to be an “acquired” lesion, albeit with anatomic precursors (1–4). The stenosis is caused by a fibrous ridge in the left ventricular (LV) outflow tract just proximal to the aortic valve. An abnormal angle between the muscular and conal ventricular septum appears to be an important causative factor, but a definitive etiology has not been established (5–7). Some investigators have considered the disease to be a form of cardiomyopathy (8), and there are patients with DSVAS who develop an unusually profound LV myocardial hypertrophic response. However, more often there does not appear to be a global cardiomyopathic component. In the vast majority of cases, LV hypertrophy regresses after relief of outflow obstruction, as would be expected in a patient with valvar aortic stenosis.