The Glenn Procedure (or hemiFontan) is the 2nd of three open-heart surgeries for children born with Hypoplastic Left Heart Syndrome. This surgery occurs somewhere between 6 and 8 months of age. It is a surgery in which a detour (shunt) is created from the aorta to the pulmonary artery. The bidirectional shunt is performed by connecting the superior vena cava to the right branch of the pulmonary artery using fine sutures, and dividing or tying up the pulmonary artery. Now, venous blood from the head and upper limbs will pass directly to the lungs, bypassing the right ventricle. The venous blood from the lower half of the body however will continue to enter the heart (this will be corrected in the 3rd surgery).
The venous blood from the upper body is re-directed first, because that is the larger part of a baby’s body. As the body grows, the lower body becomes larger, bringing the need for the 3rd surgery (The Fontan).
Recovery for the Glenn Procedure is much shorter, on average, than that of the Norwood, and oxygen saturation will improve along with overall energy. Since HLHS babies operate with a single ventricle, the Glenn Procedure will decrease the overall volume load on the single ventricle.
So why is the Glenn Procedure done so soon after the Norwood? If you remember, the Norwood-Sano procedure places a shunt in the heart that is attached to the pulmonary artery. As your baby grows, so will his heart…the shunt, however, won’t grow and will begin to stretch. It will get to a point where both ends of that shunt will begin to narrow and you’ll notice your baby’s sats begin to trend downward just a little. This is one of the signs that it’s time for the Glenn Procedure and the Norwood is definitely not a long-term solution. In fact, during the Glenn Procedure, the Sano Shunt is removed.
For more information, check out this incredible video by the Children’s Hospital of Philadelphia (CHoP): http://www.youtube.com/watch?v=fUPVkKvPGe4