32 Fetal Intervention
II. RATIONALE FOR FETAL CARDIAC INTERVENTION
A. The cardiac defect
1. The cardiac defect can have a negative impact on postnatal survival (e.g., hypoplastic left heart syndrome [HLHS] with severely restrictive or intact atrial septum).
2. The defect significantly affects quality of life.
a. Single ventricle with Fontan circulation (aortic stenosis that evolves to HLHS with a single right ventricle [RV] as the systemic ventricle).
b. Pulmonary atresia with intact ventricular septum that can lead to hypoplastic right heart syndrome and single-ventricle circulation with a single morphologic left ventricle (LV) as the systemic ventricle.
3. It can lead to fetal demise, as could occur with the evolution of severe tricuspid or mitral insufficiency with progressive severe pulmonary or aortic outflow tract obstruction, respectively.
III. TREATMENT
A. Fetal aortic stenosis
1. Fetal intervention is currently only justifiable for a severe form of aortic stenosis that has a high likelihood of evolving into HLHS or in which heart failure has evolved as a result of the severe LV dysfunction and/or mitral insufficiency.
2. Mild or even moderate forms of fetal aortic stenosis do not usually result in LV hypoplasia or fetal heart failure. The fetus can undergo neonatal balloon aortic valvuloplasty (Figs. 32-1 and 32-2) with satisfactory results and long-term outcomes.
3. The postnatal outcomes for HLHS vary among institutions.
a. The best reported survival ranges from 80% to 90% for the first-stage Norwood surgery and 70% to 80% through the Fontan stage.
b. The long-term survival beyond 20 years of age is unknown.
c. In the context of progressive heart failure or fetal hydrops, the likelihood of survival if the fetus is not at a truly viable age and size for intervention is extremely low.
4. Fetal intervention can be justified if the intent is to prevent progression of severe aortic stenosis to HLHS or fetal hydrops.
a. We select patients we believe will have HLHS at birth but whose LV is still within the normal range at the time of diagnosis.
b. Fetal echocardiography shows features of fetal aortic stenosis with evolving HLHS.
d. Contraindications to fetal intervention.
e. Fetal cardiac intervention team.
f. Outcomes and follow-up after fetal intervention for aortic stenosis.