Effect of Fetal Aortic Valvuloplasty on Outcomes

Effect of Fetal Aortic Valvuloplasty on Outcomes. A Prospective Observational Cohort Study With a Comparison Cohort

In one of the most severe congenital heart defects, hypoplastic left heart syndrome (HLHS), the left ventricle is underdeveloped and the prognosis is worse than in most other heart defects. The underdevelopment can occur gradually during fetal growth caused by a narrowing of the aortic valve. At some international centers, such fetuses are treated with a balloon dilation of the narrowed valve, but there is no scientifically sound evidence that this treatment is effective.

The aim of this study is: 1/ to evaluate whether balloon dilation during the fetal period of a narrowed aortic valve can reduce the risk of the left ventricle becoming underdeveloped and the baby being born with a so-called univentricular heart (HLHS); 2/ to investigate whether such treatment improves the prognosis for this group of children with a very complex and severe heart defect and 3/ to also describe side effects and risks in fetuses and mothers of the fetal procedure.

Routinely collected pre- and postnatal clinical data will be entered into a digital database and echocardiographic examinations will be uploaded to a server. A core lab will measure and analyze all echocardiographic examinations according to protocol. The growth of the left heart structures and the postnatal outcome will be compared between the intervention and non-intervention groups.

The decision whether a fetal balloon dilatation shall be attempted is not part of the study protocol. The number of examinations of mother/fetus/infant in this study is not different from the number of examinations that will be recommended for someone choosing not to be part of this study. Participation in the study does not affect the care and treatment mothers and fetuses are receiving during pregnancy, nor how the infant is examined and treated after birth.

Inclusion Criteria:

A. All of the following echocardiographic criteria need to be satisfied between 23+0 and 31+6 weeks (z-scores according to Schneider et al):

1. Aortic valve stenosis with antegrade flow through the valve

2. Predominantly left-to-right shunt at the atrial level

3. Predominantly retrograde flow in the aortic arch between the first two brachiocephalic vessels

4. Qualitatively depressed left ventricular function

5. Left ventricular end-diastolic diameter Z-score > ±0

6. Left ventricular inlet length in diastole :

   1. Gestational age ≤ 24+6: Z-score > ±0
   2. Gestational age 25+0 to 27+6: Z-score > -0.75
   3. Gestational age ≥ 28+0: Z-score > -1.50

7. Mitral valve diameter in diastole Z-score > -2.0

B. All of the following postnatal treatment options need to be available: 1. Surgical or catheter based aortic valvotomy 2. Ross-Konno surgery 3. Norwood or hybrid stage-one surgery

Exclusion Criteria:

1. Any associated cardiac defect except persistent left superior vena cava and coarctation of the aorta
2. Any significant (i.e. that might influence outcome) extracardiac anomaly and/or known chromosomal aberration. Also, if such a condition is present at inclusion but diagnosed only after birth the case will be retrospectively excluded.