Objective: Counseling patients with an isolated ventricular septal defect (i-VSD) is clinically important because with high-resolution ultrasound equipment, more small muscular VSDs are now being diagnosed. The prevalence of these lesions is not yet completely described, and the frequency with which muscular VSDs resolve in utero has also not been extensively reported.
Methods: We investigated the perinatal course of isolated muscular VSDs diagnosed only on color Doppler examinations and followed between January 1, 2005, and December 31, 2006. A complete evaluation of the fetal heart was performed by gray scale, spectral Doppler, and color Doppler examinations.
Results: We performed a total of 2583 fetal echocardiographic examinations on 2410 fetuses during 2318 pregnancies. The study group included 78 twin gestations (3.4%) and 7 triplet gestations (0.3%). There were 16 fetuses with an i-VSD (6.6/1000 fetuses) within the study group. The mean gestational age +/- SD at diagnosis was 23.5 +/- 4.3 weeks. Two of the i-VSDs (12.5%) spontaneously resolved prenatally. One fetus with an i-VSD had trisomy 21 and also had increased nuchal translucency in the first trimester. One i-VSD was diagnosed among 22 fetuses with trisomy 21 examined during the study period.
Conclusions: An i-VSD is a common congenital heart defect. Prenatal resolution of i-VSDs is less frequent than reported in the literature. A larger cohort is needed to provide a better risk estimate for aneuploidy in the presence of an i-VSD.