Quadricuspid aortic valve associated with non-obstructive sub-aortic membrane: a case report and review of the literature.

Quadricuspid aortic valve (QAV) is a rare congenital cardiac entity. The recognition of QAV has clinical significance because QAV causes aortic valve dysfunction, commonly aortic regurgitation. QAV is often associated with other congenital cardiac abnormalities. Our case represents, to the best of our knowledge, the first reported case of QAV with a non-obstructive sub-aortic membrane.