Objective
We report a case of acute aortic insufficiency by AV leaflet entrapment after balloon valvuloplasty(BVP) of aortic valve(AV).

Method
A 4-year-old girl underwent surgical aortic valvuloplasty with leaflet extension for congenital aortic steno-insufficiency (AsR). After operation she suffered from dizziness and decreased activity. Postoperative echocardigram showed mild aortic stenosis(AS) of peak pressure gradient(PG) 42 mmHg and minimal AR. Five months after operation, she collapsed after complaining chest pain at playground. Neurologic and cardiac evaluation showed no significant finding but mild AS of above PG. We tried BVP of the AV because we thought her symptom was related with AS despite mild PG. The PG was 40 mmHg at catheterization. The AV annulus was 15-16 mm and the sinotubular junction was narrow on angiogram. Initially we tried BVP with 12 mm balloon, but there was no change of PG. During retrial with 14mm balloon, sudden bradycardia and hypotension developed, which recovered soon after medication. However, in a few minutes bradycardia reappeared which led to cardiac arrest. Angiogram during resuscitation showed open, fixed, thick leaflet causing aortic regurgitation and narrowing left coronary sinus. Under ECMO support she underwent emergency surgery. On operation field, there was no vessel or leaflet tearing, and the left coronary sinus was small.

Conclusion
Aortic cusp entrapment is a very rare complication of BVP that results acute aortic regurgitation and possible coronary insufficiency. In a case of aortic stenosis with small coronary sinus and sinotubular junction, this complication should be concerned and BVP should be done carefully.