[Prospective study on the isolated ventricular septal defect in fetus]

Congenital heart defect is one of the most common birth defects. The isolated ventricular septal defect (VSD) has higher morbidity, and spontaneous closure may occur. Previously many studies about the prognosis of ventricular septal defect in childhood were conducted; in contrast, few studies on evolution and prognosis of ventricular septal defect from fetus to postnatal life have been available. This research aimed to determine the evolution of isolated ventricular septal defect during the period of fetus and postnatal life, and analyze the association between the diameter or location of VSD and the spontaneous closure of VSD.

All pregnant women seen at the prenatal diagnosis center of the West China Second Hospital were recruited. From June 2011 to June 2014, these participants underwent the fetal 2-dimensional and color Doppler echocardiographic examinations, and the fetuses with isolated VSD were included in the study, and those with other malformations or abnormal chromosome were excluded. This study was a prospective and longitudinal research. These fetuses were followed-up until the VSD closed spontaneously, or were surgically repaired or percutaneously closed. Outcomes of all the cases were recorded.

There were 234 fetuses with isolated VSD who were recruited in our research cohort. Twelve of 234 lost to follow-up, 5 of 234 were still in uterus. Totally 217 fetuses were followed up. One hundred eighty-nine of 217 (87.1%) cases were delivered. The pregnancies were terminated in 28 of 217 (12.9%) cases. Ten cases died after birth. Of the 179 delivered cases, the rate of VSD spontaneous closure was 45.2% (81/179), the VSD of 49 cases (27.4%, 49/179) spontaneously closed in uterus. The VSD of 17.9% (32/179) cases spontaneously closed after birth and those of 75% (24/32) cases closed in the first year of life. Furthermore, these participants were divided into 3 groups according to the diameter of VSD in fetus. There were 87 cases in ≤ 2.0 mm group, 51 spontaneously closed (59%, 51/87) and 30 of 84 spontaneously closed (36%, 30/84) in 2.1-5.0 mm group. There were no spontaneous closure in > 5.0 mm group. There was a significant difference in spontaneous closure rate between the 3 groups (χ(2) = 15.200, P = 0.001). Nevertheless, these participants were divided into 2 groups according to the location of VSD in fetus (perimembrane VSD (P-VSD) group and muscular VSD (M-VSD) group). There were 152 cases in P-VSD group, 69 spontaneously closed (45.4%, 69/152) and 12 of 27 spontaneously closed (44%, 12/27) in M-VSD group. There was no significant difference in spontaneous closure between P-VSD and M-VSD (χ(2) = 0.008, P = 0.950).

There was a high spontaneous closure rate of VSD in the period of late pregnancy. The most of postnatal VSD were spontaneously closed within one year of age. The spontaneous closure rates of fetal VSD with different diameter were different. The spontaneous closure rate of VSD with smaller diameter was higher.