Isolated ventricular septal defects demonstrated by fetal echocardiography: prenatal course and postnatal outcome


Isolated ventricular septal defects demonstrated by fetal echocardiography: prenatal course and postnatal outcome.

Raucher Sternfeld A, Sheffy A, Tamir A, Mizrachi Y, Assa S, Shohat M, Berger R, Lev D, Gindes L.

J Matern Fetal Neonatal Med. 2020 Jan 12:1-5. doi: 10.1080/14767058.2020.1712710. [Epub ahead of print]

PMID: 31928261

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Take Home Points:

  • Small muscular VSDs are common in fetal life with almost 50% closing before birth and over 90% closing by 2 years of life
  • Muscular VSDs were not associated with any chromosomal abnormalities or genetic mutations on microarray analysis, but only a small number of patients underwent testing
  • The high incidence and frequency of spontaneous closure along with no genetic abnormality may suggest that the presence of small muscular VSDs may be a delayed physiological process as opposed to something pathologic, but this premise should be studied further
  • Perimembranous VSDs are less likely to close and more likely to be associated with a genetic abnormality

Commentary from Dr. Jared Hershenson (Greater Washington DC), section editor of Pediatric Cardiology Journal Watch:  VSDs are the most common congenital cardiac malformation and often diagnosed prenatally. Most VSDs will have little hemodynamic effect prenatally due to equal pressure in both ventricles and limited shunting and many close during fetal life or within a few years after birth. This was a retrospective study looking at prenatal course and postnatal outcomes in fetuses diagnosed with VSDs over a 4 year study period of 7466 fetal echocardiograms. 59 cases of complicated CHD was seen (0.79%). 86 isolated VSDs were diagnosed (1.17%) with 11 cases excluded due to loss of follow up. 64/75 patients had muscular VSDs with a mean size of 1.1 mm and median maximal size of 1 mm. In comparison, perimembranous VSDs had a mean size of 2.5 mm and a median size of 3.5 mm.

The authors note that all fetuses with a VSD are referred for genetic consultation at this study center and each family can decide on testing. 19 fetuses subsequently had a karyotype and 4 fetuses had a complete microarray. All fetuses had normal testing except for 1 with Down Syndrome who had a perimembranous VSD. Spontaneous closure occurred in 92% of the muscular VSDs during the study period (up to 2 years) and 48.4% closed before birth. This contrasted with perimembranous VSDs, with 45.5% closing over 2 years and 27% before birth (see Table 1). Amongst all VSDs, those that closed spontaneously were significantly smaller than those that remained open (1.48 +/- 0.68 mm vs. 2.6 +/- 1.25 mm).

The authors conclude that muscular VSDs are common, are not associated with chromosomal aberrations, and often close spontaneously. They suggest that the presence of these VSDs may actually represent a delayed physiologic process rather than something pathologic. A significant caveat to this would be that very few patients in their study actually underwent genetic testing (specifically microarray) and it is possible that there may be some genetic mutations that would be associated with VSDs. However, invasive genetic testing such as amniocentesis should likely not be recommended for this patient population.

Additionally, the overall number of patients was small and while they mention size as a significant factor for spontaneous closure, nearly all of those patients had muscular VSDs anyway. I do think that this study adds to the objective ability of fetal cardiologists to reassure patients when small muscular VSDs are seen even though most of us have recognized this by experience.