Predictors of technical success and postnatal biventricular outcome after in utero aortic valvuloplasty for aortic stenosis with evolving hypoplastic left heart syndrome

Abstract

Background: Aortic stenosis in the midgestation fetus with a normal-sized or dilated left ventricle predictably progresses to hypoplastic left heart syndrome when associated with certain physiological findings. Prenatal balloon aortic valvuloplasty may improve left heart growth and function, possibly preventing evolution to hypoplastic left heart syndrome.

Methods and results: Between March 2000 and October 2008, 70 fetuses underwent attempted aortic valvuloplasty for critical aortic stenosis with evolving hypoplastic left heart syndrome. We analyzed this experience to determine factors associated with procedural and postnatal outcome. The median gestational age at intervention was 23 weeks. The procedure was technically successful in 52 fetuses (74%). Relative to 21 untreated comparison fetuses, subsequent prenatal growth of the aortic and mitral valves, but not the left ventricle, was improved after intervention. Nine pregnancies (13%) did not reach a viable term or preterm birth. Seventeen patients had a biventricular circulation postnatally, 15 from birth. Larger left heart structures and higher left ventricular pressure at the time of intervention were associated with biventricular outcome. A multivariable threshold scoring system was able to discriminate fetuses with a biventricular outcome with 100% sensitivity and modest positive predictive value.

Conclusions: Technically successful aortic valvuloplasty alters left heart valvar growth in fetuses with aortic stenosis and evolving hypoplastic left heart syndrome and, in a subset of cases, appeared to contribute to a biventricular outcome after birth. Fetal aortic valvuloplasty carries a risk of fetal demise. Fetuses undergoing in utero aortic valvuloplasty with an unfavorable multivariable threshold score at the time of intervention are very unlikely to achieve a biventricular circulation postnatally.

Figure 1

Flow diagram depicting procedural, pregnancy, and postnatal outcomes among 70 fetuses that underwent attempted prenatal aortic valvuloplasty for AS with evolving HLHS.

Figure 2

Mean±SD Z scores of the aortic annulus (A), MV annulus (B), LV short axis (C), and LV long axis (D) at the time of prenatal intervention and at the latest follow-up fetal echocardiogram with adequate data in fetuses with a biventricular outcome after technically successful intervention (from birth or after initial univentricular staging), fetuses with a univentricular outcome after technically successful intervention (single ventricle), and comparison fetuses (control).

Figure 3

Box plots depicting the rate of change in aortic annulus, ascending aorta, and MV dimensions (A) and LV long- and short-axis and RV long-axis dimensions (B) in fetuses that underwent successful intervention and comparison group fetuses. All measures are expressed in millimeters per week, with positive numbers indicating an increase in size and negative numbers indicating a decrease. For each plot, the central line represents the median rate of change; box, the interquartile range; and whisker bars, 95% confidence intervals. Outliers are shown individually.

Figure 4

Distribution of threshold scores according to biventricular or univentricular outcome postnatally. White shading indicates fetuses with a univentricular outcome; gray shading, those with a biventricular outcome from birth; and hatched shading, the 2 that initially underwent univentricular staging and were later converted to a biventricular circulation.