Echogenic Intracardiac Foci

What are echogenic intracardiac foci (EIF)? EIF are small, echogenic lesions seen (on sonography) inside the left or right ventricles of the fetal heart within the papillary muscles or chordae tendinae. These lesions are not attached to the wall of the ventricles.

The lesion must be of the same echogenicity as fetal bone and move with fetal heart motion. These echogenic foci were once also called “golf balls” or “peas.”

Incidence
EIF are seen in about 4% of all pregnancies on sonography. There is relatively higher incidence of EIF among Asians, with a survey reporting almost 12% to 13 % in this group.

The risk of aneuploidy in fetuses with EIF is definitely higher than in fetuses without EIF. This is more pronounced in the fetuses of mothers aged older than 35 years. However, in most cases this finding does not appear very significant and may be considered a normal variant. In addition, the presence of multiple EIF within the same ventricle or on both sides (right and left ventricles) is found to be associated with higher risk of fetal aneuploidy.

The risk of Trisomy 21 is higher in fetuses with bilateral or multiple foci.

There is also said to be a small but important risk for congenital heart disease in the fetus. Hence, the fetal heart has to be carefully evaluated for cardiac defects.

Ultrasonography Features
EIF are most often seen in the left ventricle (94%) and are usually single. They usually measure 1 to 4 mm in size. The images below show a typical case of EIF measuring 4 mm, which is located in the left ventricle (arrow) in a late 2nd trimester fetus.

Figure 1a Typical case of EIF.

Figure 1b

Prognosis
In most cases (97%) the EIF persists into the 3rd trimester and even into the neonatal period. However, in about 35% of cases the foci increase in size, while in 12% of cases they may become smaller. In about 50% of cases the foci remain stable in size until the neonatal period. By transvaginal sonography EIF may be seen as early as 14 weeks in 7% of women. However, these may disappear toward late 2nd trimester.

Etiology and Mimics
EIF represent either calcification and/or microscopic fibrosis within the papillary muscle or chordae tendinae of the ventricles. Some have suggested that these foci represent incomplete fenestration of the chordate tendinae.

The following conditions may mimic EIF:

• Fetal cardiac tumors such as rhabdomyomas may undergo calcification and mimic an EIF. Thus it is important to carefully image the heart to rule out such masses.
• Endocardial fibroelastosis is a condition in which the endocardiaum of the fetal heart may undergo fibrosis and calcification, mimicking the appearance of an EIF.

References:

References

Bromley B, Lieberman E, Shipp TD, et al.Significance of an Echogenic intracardiac focus in fetuses at high and low risk for aneuploidy.  JUM 1998;17:127-131.
Filly RA, Benacerraf BR, Nyberg DA, Hobbins JC.Choroid plexus cyst and Echogenic intracardiac focus in women at low risk for chromosomal anomalies.  JUM 2004;23:447-449.
Lim L, Aptekar L, Bombard A, et al. Ethnicity and other factors that may affect the prevalence of Echogenic intracardiac foci in the fetus. J Clin Ultrasound 2006;34:327-329.
Rodgers BD. Intracardiac Echogenic Foci. Unpublished paper from the Division of Maternal-Fetal Medicine and Fetal Cardiovascular Medicine. SUNY Buffalo.
Ultrasound images of anomalies of the fetal heart. Ultrasound-images Web site. Accessed August 18, 2011.