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.
Aortic valve stenosis with antegrade flow through the valve
Predominantly left-to-right shunt at the atrial level
Predominantly retrograde flow in the aortic arch between the first two brachiocephalic vessels
Qualitatively depressed left ventricular function
Any associated cardiac defect except persistent left superior vena cava and coarctation of the aorta
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.
The study population consists of fetuses and children with aortic valve stenosis and/or hypoplastic left heart syndrome
Cohort
Prospective
Fetal aortic balloon dilatation
Procedure/SurgeryFetal valvuloplasty will be performed as described in Arzt W, Wertaschnigg D, Veit I, Klement F, Gitter R, Tulzer G. Intrauterine aortic valvuloplasty in fetuses with critical aortic stenosis: experience and results of 24 procedures. Ultrasound Obstet Gynecol. 2011;37:689-695. with minor variations between centers involved. Technical success is defined as improved forward flow and/or new aortic regurgitation.
Transplantation-free survival
Transplantation-free survival from fetal diagnosis to 2 years postnatal age with a biventricular circulation without pulmonary hypertension at that time. Absence of pulmonary hypertension is defined as a TR max velocity ≤ 2.8 m/s with no other echocardiographic signs of pulmonary hypertension and/or catheter data showing a mean pulmonary arterial pressure \<25 mmHg.
Intervention-related fetal death
Intervention-related fetal death (defined as fetal death within 24 hours of procedure)
Fetal death not directly related to the intervention
Fetal death not directly related to the intervention, except termination of pregnancy
Maternal complications to fetal intervention procedure
Maternal complications to procedure requiring intensive care or resulting in maternal death
Preterm delivery
Preterm delivery before 37 weeks gestational age
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Queen Silvia Children's Hospital, Gothenburg, Sweden
Lead sponsor
Swedish Heart Lung Foundation
Collaborator
Sahlgrenska University Hospital
Collaborator
