Left ventricular outflow tract obstruction after partial atrioventricular septal defect repair

Narrowing of the left ventricular outflow tract has been associated with partial atrioventricular septal defect (PAVSD) in about 3% of patients. Because of the predisposing anatomy, hemodynamically significant obstruction in the subaortic area may appear after repair of ostium primum atrial septal defects.

From 1984 to 1998, 40 patients underwent surgical correction of PAVSD by patch closure. The mean age at the initial repair was 5.8 years (range 3 months to 22 years).

Nine patients had 12 subsequent operations for hemodynamically significant subaortic obstruction. The mean age at PAVSD repair was 17 months (3 to 42 months) (p < 0.001 compared with others). Follow-up work-up was obtained due to symptoms in 5 patients and an abnormal echocardiogram in 4 asymptomatic patients. Subaortic stenosis developed at a mean of 5 years (range 4 months to 10 years), and 6 or more years in 4 patients. The mean age at subaortic stenosis repair was 6 years (range 2 to 12 years). Nine patients underwent subaortic fibromuscular resection. Of these, 4 developed recurrent stenosis and 2 have undergone additional operations.

Left ventricular outflow tract obstruction after PAVSD repair may be more frequent than reported. Because of the progressive nature of the process, echocardiography should be utilized liberally on patients to uncover subclinical stenosis. Long-term follow-up is essential for diagnosis due to delayed appearance and lack of reliable clinical signs.