Right Ventricular Outflow Obstruction by a Membranous Septal Aneurysm in a Ventricular Septal Defect

Abstract

We report the case of a 5-year-old girl with a ventricular septal defect (VSD) complicated by stenosis of the right ventricular outflow tract due to a giant membranous septal aneurysm. The patient had a heart murmur at birth, and was diagnosed with membranous VSD and aortic coarctation. At 3 months old, the VSD showed signs of spontaneous closure and a mild left-to-right (LR) shunt was observed. Therefore, surgery for aortic constriction was performed as a follow-up for the VSD. At 4 years old, echocardiography revealed a giant membranous septal aneurysm protruding into the right ventricular outflow tract, and cardiac catheterization was performed. The Qp/Qs, right ventricular systolic pressure and pulmonary artery systolic pressure were 1.0, 79 mmHg and 26 mmHg, respectively, and right ventricular outflow stenosis was revealed. Although adult cases of membranous septal aneurysms that result in right ventricular outflow stenosis have been reported, pediatric cases are rare. Given such complications, careful observation is necessary for VSDs with a mild LR shunt.