Echocardiographic assessment of subvalvular aortic stenosis before and after operation

The development of two-dimensional and Doppler echocardiography has provided a noninvasive technique for the diagnosis and serial assessment of patients with subvalvular aortic stenosis. The clinical records and echocardiographic data were reviewed of all patients with subaortic stenosis diagnosed between 1983 and 1991. Of the 77 patients identified (45 male and 32 female), 28 had isolated subaortic stenosis and 49 had associated cardiac lesions. The most frequently encountered associated lesions were ventricular septal defect (n = 19) and coarctation of the aorta/interrupted aortic arch (n = 14). Serial echocardiographic studies, performed in 38 of the 77 patients, documented significant progression of the left ventricular outflow tract gradient in 25 patients (66%) and development of aortic regurgitation in 25 patients (66%). Surgical resection was performed in 36 patients. The preoperative outflow tract peak gradient was 62.9 ± 31 mm Hg (range 0 to 153), whereas the immediate postoperative gradient was 14.4 ± 14 mm Hg (range 0 to 67). The two patients with a significant residual gradient (37 and 67 mm Hg, respectively) in the immediate postoperative period had severe subaortic stenosis preoperatively with marked left ventricular hypertrophy and intracavitary gradient. The immediate postoperative echocardiograms demonstrated no worsening of aortic regurgitation in any patient and regression of regurgitation in one patient from mild to none. Intermediate-term follow-up studies were available for review in 13 postoperative patients at a mean of 4 years postoperatively. In 2 (15%) of these 13 patients, subaortic stenosis recurred; however, the degree of aortic regurgitation did not increase in any patient. Thus, in patients with subaortic stenosis, progression of the left ventricular outflow tract gradient and development of mild aortic regurgitation are common. After surgical repair, recurrence of subaortic stenosis and progression of aortic regurgitation are rare. Two-dimensional and Doppler echocardiography are extremely useful techniques for the diagnosis and serial assessment of patients with subvalvular aortic stenosis.