Wired:

An infant named Grace, who underwent the world’s first heart “stent” procedure in the womb was discharged to go home last week, according to a press release from Children’s Hospital Boston, the center where the landmark operation took place.
The stent was placed in the developing fetus at 30 weeks of pregnancy on Nov. 7 to treat a heart defect called hypoplastic left heart syndrome (HLHS). She was born Jan. 10 and underwent the first part of a definitive three-stage corrective operation three days later. The physicians credit the earlier stent placement with protecting her lungs and making her recent operation run more smoothly than usual for these types of cases.
With HLHS, the most common heart disease-related cause of death during the first week of life, the left side of the heart is underdeveloped and can accept very little blood. Frequently, there is a hole that lets blood from the left side flow to the right before leaving the heart. In Grace’s case, however, there wasn’t a hole, so blood accumulated on the left side and backed up into her lungs, which over time can cause serious damage.
To prevent the lung damage that would occur as the pregnancy went on, Dr. James Lock, from Children’s Hospital Boston, and colleagues decided to create a connection between the left and right sides of Grace’s heart using a stent, which acted like a tiny channel for the blood.
Under ultrasound guidance, the doctors inserted a small catheter into the mother’s abdomen and uterus and then into the fetal heart. After two holes were created in the wall between the left and right sides of the heart, the stent was placed.