Isolated congenital absence of a single pulmonary valve cusp.

Isolated absence of a single pulmonary valve is extremely unusual. We present a 16-year-old male with the absence of one cusp resulting in significant pulmonary regurgitation, right ventricular enlargement, and dilatation of the main pulmonary artery and its branches. Surgery consisted of creating a valve cusp from the posterior wall of the pulmonary artery at the base of the pulmonary trunk. Follow-up at 3.5 years revealed good results with only mild pulmonary stenosis and regurgitation.