Most common etiology in children is Tetralogy of Fallot, single ventricle with severe pulmonary stenosis.
Collaterals can develop in Tetralogy of Fallot who did not undergo total correction at right time, or can be there is single ventricle pathway like situation with severe pulmonary stenosis, or after operation e.g. Fontan or Glenn shunt.
Collaterals can form between great artery that supplies the body and lung vasculature.
We need to close these collaterals before proceeding for final repair of the concerned disease.
We need to take artery in leg known as femoral artery for accessing these collaterals. We define these collaterals by angiography. Then by hooking these abnormal channels, we either close these by coils, glue or gel foam etc.
Sedation during the procedure depends on age of the patient.