Echogenic intracardiac focus

Echogenic intracardiac focus (EIF) is a relatively common sonographic observation that may be present on an antenatal ultrasound scan.

Epidemiology

They are thought to be present in ~4-5% of karyotypically normal fetuses. They may be more common in the Asian population ⁵.

Associations

• trisomy 21 (Down syndrome): may be present in up to 12% of fetuses

• trisomy 13

The tightness of the association between an isolated echogenic intracardiac focus and aneuploidy continues to be debated. Biventricular echogenic intracardiac foci are considered to be a higher risk for aneuploidy.

Pathology

They are considered to represent mineralization within the papillary muscles.

Location

The majority of echogenic intracardiac foci are unilateral. Out of all the cardiac chambers, the left ventricle is the most frequent in terms of location.

Radiographic features

Antenatal ultrasound

They are typically seen as a small bright echogenic focus within the fetal heart on a four chamber view (often as bright as bone).

Tissue harmonic imaging should be turned off when evaluating a potential echogenic intracardiac focus, to avoid false positives. If it is difficult to tell if the focus is as bright as bone, the gain in the image can be decreased to see which structure disappears first.

It is usually single and less than 3 mm. 

It needs to be differentiated from normal papillary muscle which is not as bright as bone and a moderator band which is situated at the ventricular apex.

Treatment and prognosis

The presence of an echogenic intracardiac focus has to be interpreted in the context of maternal risk factors and other sonographic anomalies.

When seen incidentally in isolation in a normal pregnancy, it is considered a benign variant and some authors state karyotyping is unwarranted in the mid-trimester ⁸. There is no recognized direct association with congenital heart anomalies for an isolated echogenic intracardiac focus ¹ (unless there is an associated aneuploidic anomaly).

In high-risk pregnancies, there is an increased incidence of aneuploidy (e.g. Down syndrome ^2,3 and trisomy 13 ³) and it is classified as a soft marker. The presence of multiple or bilateral (more than one chamber) echogenic foci is considered to increase the risk.

They usually disappear during the 3^rd trimester ⁷.