Background: As many as forty to fifty per cent of children with Down syndrome are born with a cardiac anomaly. Sinus of Valsalva aneurysm in this syndrome is extremely rare, only three previous reports, and of adult onset.
Case Report: An asymptomatic 9 and a half year boy with Down syndrome presented with a cardiac murmur at routine examination. Clinical examination, transthoracic and transesopahageal echocardiography revealed the presence of a ruptured sinus of Valsalva aneurysm from the non - coronary sinus protruding into the right atrium. The child underwent successful surgical repair with full recovery.
Conclusions: This fourth case report of sinus of Valsalva aneurysm occurring in association with Down syndrome is the youngest to date. Physicians caring for Down syndrome patients ought to be aware of this late onset cardiac malformation. Serial echocardiographic assessment of the aortic sinus of Valsalva in these patients may offer early detection.

Keywords: Heart Defects, Congenital - ultrasonography, Down Syndrome - complications, Child, Aortic Rupture - ultrasonography, Sinus of Valsalva - ultrasonography