Cardiac Abnormalities of the Fetus

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.