Ebstein's anomaly (EA) is a rare congenital heart disorder. Fetal diagnosis and presentations of the disease are typically the most severe and are associated with the highest mortality rates5,6. In the present study, we found that fetal echocardiography is a preferred tool to accurately diagnose the lesion. Generally, we can quickly make an accurate judgment on the disease on the four-chamber view for the disease. The images mainly showed that the tricuspid septal and posterior lobe could shift down, causing severe dysplasia. The anterior lobe is attached to the annulus' average level, which may be larger or sail-shaped6.
Nonetheless, each patient has its characteristics, mainly manifested in the differences among the tricuspid septal lobe, posterior lobe lesions, and occasionally anterior lobular abnormalities that shift down or block the right ventricular outflow tract. Additionally, the right ventricle looks abnormal, the right ventricle cavity below the tricuspid valve significantly reduced, and the trabecular part also becomes smaller7–8. The narrowed funnel part includes residual valve tissue or abnormal muscle bundles or fiber bundles8. The 53 cases of EA fetuses in this study were all diagnosed by echocardiography, and each fetal’s pathology has its characteristics.
The diagnose of EA can prenatally be granted the prenatal ultrasound examination reveals the above manifestations of the fetal heart. Since this complex congenital anomaly has a very variable anatomical and clinical spectrum, early diagnosis can provide patients with a timely and effective perinatal treatment plan. These outcomes are consistent with previous studies describing9,10,11 the high detection rate of other congenital complex diseases with prenatal ultrasound, indicating that echocardiography is worth pursuing in clinical practice.
Fetuses diagnosed with EA have a poor prognosis, and the total mortality rate is as high as 80% or more12. Mild EA had a better prognosis compared to severe EA. However, when combined EA with other diseases, the prognosis is worse, consistent with our study's conclusions. Other studies also reported that factors, including fetal edema, cardiac hypertrophy, outflow obstruction, and cardiothoracic ratio > 0.55, suggest poor prognosis for the fetuses13. Upon longer duration of TV malformation, the disease will be getting severe gradually; the right heart will be overloaded, thus inducing right heart failure and increasing the burden of the right heart.
In severe cases, the right heart can be twice the size as the left heart, indicating that the fetus's prognosis is inferior and requires timely treatment to ensure the fetal's safety. Issues regarding the importance of the atrialized chamber have also been raised14–15. In this study, only one fetus was regularly followed up and examined by our center with an induction rate of 98.11% (1/53), which is much higher than EA patients' mortality rate in previous studies. The main reason is that fetuses with severe or severely late tricuspid regurgitation and those with combined malformations account for a large proportion of cases.
Our center is a cardiovascular hospital, and most of the patients are mothers with critically ill fetuses. Although we can make the diagnosis in time, the treatment efforts during the perinatal period cannot be exerted, contributing to patients' low birth rate. Such a high induction rate can also explain the high proportion of grade-Ⅲ and grade-Ⅳ in prognosis's grading area in our study. On the other hand, it also shows that we can identify more congenital heart diseases in the fetal period with examination assistive technology. It is noteworthy that the high detection rate is also a factor contributing to the increase in the death rate, although this needs further verification.
Although this is a relatively larger cohort of fetuses with EA, the sample size is still relatively small, limiting to providing a firm conclusion. Additionally, this is a single-institutional retrospective study. Many patients were coming to us from other centers. As a result, potential patient selection bias may have led to the data, and the results presented here may not be directly applicable to other centers and populations.