Quadricuspid aortic valve as a cause of severe aortic regurgitation.

Quadricuspid aortic valves (QAVs) constitute a rare congenital malformation, with an incidence ranging from 0.008 to 0.048%. We report a case of severe aortic regurgitation associated with a QAV, which was diagnosed intraoperatively using transesophageal echocardiography. Since the first case described in 1862, 186 QAVs have been reported. In most cases, QAVs are associated with valve regurgitation, with a concurrent stenosis in some patients, while only a small number of QAVs are functionally normal. Once the diagnosis has been made, echocardiographic follow-up is recommended, as progression to severe valve regurgitation is common. Antibiotic prophylaxis is advisable for dental, and "dirty" surgical procedures, to minimize the risk of infective endocarditis.