In an attempt to improve left ventricular function and growth, prenatal balloon aortic valvuloplasty has been performed at some centers to widen the stenotic aortic valve and help the fetal heart develop more normally.
This procedure is generally done under maternal anesthesia. Ultrasound images guide placement of the needle. Anesthesia is also administered to the fetus and the needle is then inserted through the fetal chest wall and into the fetal heart. A thin tube (catheter) with a special balloon attached is inserted and the balloon is inflated to expand the narrowed valve so blood can flow through it more easily. The tube and the needle are then removed.
Success of the procedure depends on many factors, including position of the fetus within the womb. Early studies have shown that the valve was expanded in at least half of fetuses undergoing the procedure. Some mothers experienced bleeding after the procedure and needed to have an emergency caesarean section. The long-term risks and benefits of the procedure remain unknown.
As most fetuses with aortic stenosis with remain stable in the mother’s womb, fetal balloon aortic valvuloplasty has usually been limited to fetuses with poor prognosis, who are likely to progress to hypoplastic left heart syndrome. Typical findings in such fetuses include:
- Valvular aortic stenosis
- Severe left ventricular systolic dysfunction
- Left-to-right flow at the atrial septum or patent foramen ovale (PFO), an opening in the wall between the left and right atria of the heart
- Retrograde flow in the transverse aortic arch
- Gestational age between 20 and 28 weeks of age (although valvuloplasty may be considered past 28 weeks if the fetus has also developed hydrops or swelling)
Serial fetal echocardiography should be performed every two-four weeks, both in mothers who undergo a fetal therapeutic procedure and those who do not. These echocardiograms will assess and monitor cardiac function and growth of the structures of the heart to compare the results of fetuses that undergo therapy and those that do not.