The bidirectional Glenn anastomosis is typically performed in infants aged 3-10 months to decrease the amount of time during which the right ventricle is subject to volume overload. Cardiac catheterization is performed prior to this procedure to evaluate pulmonary vascular resistance, pulmonary artery anatomy, tricuspid valve regurgitation, and right ventricular function, all of which are important in determing the timing of the surgery and the way it should be done. Cardiac catherization is bascially a procedure where a long, thin, flexible tube called a catheter is put into a blood vessel in the arm, groin (upper thigh), or neck and threaded to the heart. Through the catheter, the doctor can do diagnostic tests and treatments on the heart.

       In place of the Glenn procedure, a surgeon could proceed with the Hemi-Fontan procedure. The hemi-Fontan procedure has the same physiologic factors as a bidirectional Glenn anastomosis but it includes a connection of the pulmonary arteries to an incision in the atriocaval junction. Furthermore, there are some advantages to conducting this procedure. It shortens the length of time of cardiopulmonary bypass and dissection required for the completion of the Fontan procedure, the third procedure that is done to help a child with HLHS. In addition, the routine augmentation of the branch pulmonary arteries helps optimize the anatomy for the completion of the Fontan procedure.