Fetal Heart Conditions – What You Should Know
Overview
Some babies develop serious heart problems while still in the womb. One of the most concerning is a condition called aortic stenosis, where a valve in the baby’s heart becomes too narrow. If left untreated, this can lead to a much more severe condition called hypoplastic left heart syndrome (HLHS)—where the entire left side of the heart is too small to support the baby’s body after birth.
Without treatment after birth, HLHS is fatal. Even with surgery, children face long-term health risks, including possible delays in brain and nervous system development. Current surgeries can help about 75% of these babies survive five years or more, but they require multiple operations and lifelong care.
Can It Be Treated Before Birth?
In some cases, doctors may be able to perform a special fetal heart procedure during pregnancy to try to prevent HLHS from developing. This is still considered experimental and is only offered at select specialized centers.
The procedure involves:
- Inserting a thin needle through the mother’s belly and into the baby’s heart
- A tiny balloon is guided through the needle and inflated to open the narrow heart valve
- This may help the heart grow more normally and reduce the need for major surgeries after birth
Other Heart Conditions
Other fetal heart issues, such as:
- Pulmonary stenosis (narrowing on the right side of the heart)
- HLHS with blocked blood flow inside the heart
- Fetal heart block (abnormal electrical signals in the heart)
…are also being studied for possible before-birth treatments.
Fetal intervention for select cardiac disease is currently in the investigational stage. One area of interest is fetal critical aortic stenosis, which has been shown to evolve into hypoplastic left heart syndrome (HLHS). It is believed that fetal aortic stenosis develops into HLHS because of blood flow changes in the heart that occur while the baby is in the womb. In newborns with HLHS, the left heart is too small to support the systemic circulation, and affected newborns die without intervention. Surgical repair after birth (staged surgical palliation) results in a five-year survival rate of about 75%. However, survivors face lifelong risks including long-term neurodevelopmental deficits.
Aortic stenosis may be relieved in utero via aortic balloon valvuloplasty, and has been shown both in animal studies as well as in human fetuses to promote left ventricular growth, in some cases preventing the development of HLHS. This procedure is performed using a needle that is placed into the fetal heart through which the balloon catheter is passed. Other congenital heart malformations, such as pulmonary stenosis, HLHS with restricted atrial septum, and congenital heart block, have also been targeted as potentially amenable to fetal intervention.