The tricuspid and mitral valves of the heart are attached to small papillary muscles within the heart by fibrous strands called the chordae tendineae. The papillary muscles act to stabilize the valves when the ventricles contract. Echogenic intracardiac foci (EIF) or "bright spots" in the heart are believed to be caused by an increased reflection of sound off the small papillary muscles or chordae tendineae. These bright spots are most often a normal variant and have no significant effect on the development of the heart. EIF may be seen in up to 30, 6, and 11 % of Asian, black, and white fetuses respectively [1]. EIF are found in 13 to 18% of fetuses with Down syndrome [2]. Ultrasound findings that occur more commonly in fetuses with Down syndrome are called markers. The isolated finding of an EIF appears to increase the likelihood of Down syndrome by 1.8 to 2.8 times [3, 4] according to two studies. However, one study found that an isolated EIF in the fetal heart in women aged 18-34 years was not associated with increased risk for Down syndrome [5]. |
|
Presently genetic testing of the fetus (amniocentesis) is offered in California if the risk of Down syndrome in the fetus is 1 in 190 or greater. As the table below illustrates for a woman less than 32 years of age at delivery the finding of an echogenic focus does not increase the likelihood of Down syndrome enough to recommend routine amniocentesis.
| Maternal Age At Delivery | Midtrimester Risk of Down Syndrome Based on Maternal Age | Risk of Down Syndrome Based on Maternal Age With EIF |
| 30 | 1 in 700 | 1 in 250 |
| 31 | 1 in 613 | 1 in 219 |
| 32 | 1 in 526 | 1 in 188 |
For women 32 years of age at delivery the increased likelihood of Down syndrome, by some reports, would be sufficient enough to offer amniocentesis.
If an echogenic intracardiac focus is found on routine ultrasound then a targeted level II sonogram is usually recommended.
- To distinguish an EIF from a fetal cardiac tumor. Fetal cardiac tumors are most commonly found within the cardiac muscle or septum. Cardiac tumors tend to be larger, multiple, and are not as echogenic as the typical "echogenic focus"
- To identify additional markers for Down syndrome if present.
The use of the EIF as a marker for Down syndrome in the fetus of an Asian mother is questionable due to the increased frequency of EIF as a normal finding in the Asian population.
- In non-Asian populations genetic testing of the fetus (amniocentesis) may be recommended with detection of an isolated EIF, if serum screening (ExAFP) indicates a risk for Down syndrome greater than or equal to 1 in 531 or the patient is 32 years of age or older at delivery.
REFERENCES
1. Shipp TD, et al. The frequency of the
detection of fetal echogenic intracardiac foci
with respect to maternal race. Ultrasound
Obstet Gynecol. 2000 ;15:460-2. PMID: 11005111
2. Bromley B, et al Significance of an
echogenic intracardiac focus in fetuses at
high and low risk for aneuploidy.J Ultrasound
Med. 1998;17:127-31. PMID: 9527573
3. Nyberg DA, et al . Isolated sonographic
markers for detection of fetal Down
syndrome in the second trimester of
pregnancy. J Ultrasound Med. 2001;20:1053-
63. PMID: 11587012
4 . Smith-Bindman R, et al. Second-trimester
ultrasound to detect fetuses with Down's
syndrome. JAMA 2001;285:1044-55 PMID: 11209176
5. Anderson N and Jyoti R Relationship of
isolated fetal intracardiac echogenic focus to
trisomy 21 at the mid-trimester sonogram in
women younger than 35 years.Ultrasound Obstet Gynecol. 2003 ;21:354-8. PMID: 12704743
Created: 6/1/2004
Updated 5/25/2007