BACKGROUND:Unicuspid anatomy of the aortic valve is infrequent but may require intervention by age 40 for severe regurgitation. We propose a new repair technique for the regurgitant unicuspid valve by converting it into a bicuspid aortic valve. METHODS:Between November 2003 and September 2007, 20 patients underwent regurgitant unicuspid aortic valve repair: 13 had aortic regurgitation (AR) and 7 had combined regurgitation and stenosis. Four patients had previously undergone balloon valvuloplasty for critical aortic stenosis. The aim of the repair was to construct a bicuspid valve with two normal commissures and unrestricted cusp motion. The fused cusp tissue was divided anteriorly and a new commissure of normal height was created. Noncoronary and right coronary cusps were extended with autologous pericardium. Concomitant operations included ascending aortic replacement in 7 and resection of subaortic stenosis in 1. RESULTS:No early or late deaths occurred. Intraoperative echocardiography revealed minimal or no AR in 19 patients. Follow-up was 4 to 47 months. One patient underwent valve re-repair for recurrent and progressive aortic regurgitation 3 years postoperatively. All other valves remained stable throughout the follow-up period. Freedom from relevant aortic insufficiency (> or = II) at 4 years was 77%; freedom from reoperation was 67%; and freedom from valve replacement was 100%. CONCLUSIONS:The regurgitant unicuspid aortic valve can be repaired successfully and reproducibly by converting it into bicuspid anatomy. The functional results are comparable with those obtained in reconstructed bicuspid aortic valves. With this approach, replacement can be avoided in most patients with regurgitant unicuspid aortic valves.