Isolated ventricular septal defects in the era of advanced fetal echocardiography: risk of chromosomal anomalies and spontaneous closure rate from diagnosis to age of 1 year.

OBJECTIVES: To evaluate, in a cohort of 248 fetuses seen at a tertiary referral center, the frequency of isolated ventricular septal defects (VSD) among all congenital heart defects (CHD), the association with chromosomal and postnatal anomalies and the rate of spontaneous closure.

METHODS: This was a 6-year study on 10,800 women referred for fetal echocardiography, with 995 confirmed cases of CHD. The prevalence and characteristics of VSDs were analyzed, including follow-up until 1 year of age. Multivariate binary logistic regression analysis was performed to test the independent contribution of the ratio of the diameter of the VSD to that of the aorta (VSD/aorta ratio) (< 0.5 or ≥ 0.5) and location of VSD (perimembranous or muscular) in the prediction of spontaneous closure before the age of 1 year.

RESULTS: Two hundred and forty-eight VSDs (24.9% of all CHDs) were diagnosed, of which 216 (87.1%) were muscular and 32 (12.9%) perimembranous. Median gestational age at diagnosis was 30.4 (range, 17-41) weeks and mean size 2.6 ± 0.77 mm. Clinically relevant chromosomal anomalies were found in one (3.1%) perimembranous VSD compared with none in 216 muscular defects (P = 0.12). Postnatal malformations were diagnosed in eight of the 211 cases (3.8%) evaluated at 12 months postpartum. Spontaneous closure occurred prenatally in 13 fetuses (5.2%) and postnatally in 151 of the 198 infants (76.3%) who had an open VSD at birth. Closure was predicted by the VSD/aorta ratio (odds ratio (OR) 0.445 (95% CI, 0.216-0.914); P < 0.03) and location (OR 0.385 (95% CI, 0.160-0.926); P < 0.03).

CONCLUSIONS: In our fetal cardiology unit, isolated muscular VSD is today the most prevalent CHD. In contrast to the findings of postnatal studies, muscular VSDs were more common than perimembranous VSDs. Perimembranous VSDs were associated with a higher risk of chromosomal anomalies than were muscular VSDs, which had a similar risk to those of normal pregnancies. Spontaneous closure of the VSD was frequent and occurred in most cases postnatally.