Synonyms: Ebstein anomaly, tricuspid valve downward displacement.

Definition: Ebstein anomaly is a congenital defect characterized by downward displacement of the septal and posterior leaflets of the tricuspid valve, with dysplasia of this valve. The valve is redundant with adhesion of the posterior and septal leaflet to the right ventricular wall. The portion of the right ventricle between the untethered valve and the annulus is called the “atrialized portion of the right ventricle”.

Prevalence: 0.2-0.5:10,000, 0.5% of congenital cardiac disease¹⁴.

Etiology: Multifactorial inheritance. Ebstein anomaly of the tricuspid valve has been reported to occur in 10% of cases of chronic maternal lithium intake during pregnancy¹.

Pathogenesis: The atrioventricular valve forms by undermining of the endocardium in the 13-16 mm embryo. Ebstein anomaly results from a failure of this mechanism.

Associated anomalies: Atrial septal defect (secundum type or patent foramen ovale), pulmonary atre­sia or stenosis, patent ductus arteriosus, tetralogy of Fallot, co­arctation of the aorta, atrioventri­cular canal, and transposition of the great vessels may be associated².

Differential diagnosis: Tricuspid insufficiency without displacement; Uhl anomaly; pulmonary atresia with intact ventricular septum and tricuspid insufficiency.

Prognosis: The disorder has a wide spectrum of manifestations. In the absence of tricuspid regurgitation, this condition may be completely asymptomatic. Such patients do not develop symptoms until adolescence or adult life. On the other hand, symptomatic newborns often develop congestive heart failure³. Information on the natural history of Ebstein anomaly, based on an experience of 67 patients, was provided by Giuliani et al⁴. Mortality in this series was found to be affected primarily by four factors: New York Heart Association class III or IV; cardio­megaly; cyanosis or hypoxia; and diagnosis in infancy⁴.

Recurrence risk: Unknown.

Management: When the diagnosis is made before viability, the option of pregnancy termination should be offered. A careful search for associated cardiac and extracardiac anomalies, including karyotype, is recommended for all cases. Serial ultrasound examination should be performed to search for signs of congestive heart failure. The association of hydrops with a structural cardiac defect is an ominous combination. The optimal management of these patients has yet to be established. In the absence of congestive heart failure, there is no indication to alter standard obstetrical management, but delivery in a tertiary care center where a pediatric cardiologist is immediately available is mandatory³.

MESH Ebstein"s anomaly BDE 0332 MIM 224700 ICD9 746.2 CDC 746.200

Address correspondence to: Kohkichi Hata, MD, PhD, Dept. of Obstetrics and Gynecology, Shimane Medical University, Izumo 693, Japan. Ph: 81-85-3-23-2111 (ext 2735); Fax: 81-85-3-21-7443

Introduction

Using conventional real-time ultrasound, we can assess the structures of fetal heart and the antenatal morphological aspects^5-7 of congenital heart anomalies. With recent advances in fetal color Doppler echocardiography, antenatal Doppler color flow mappings of congenital heart disease have been documented^8,9. Some authors have demonstrated  the benefits of using color flow mapping for evaluation of fetal structural heart diseases and have demonstrated the clinical impact of this technique ^9,11.

We present a case of Ebstein anomaly diagnosed in utero at 33 weeks of gestation and discuss the abnormal intracardiac hemodynamics assessed by color and pulsed Doppler ultrasound.

Case report

A 28-year-old Japanese woman, G₁P₁, visited Shimane Medical University Hospital at 33 weeks gestation for her prenatal care. Her pregnancy course had been uneventful. At this time, frequent uterine contractions were pointed out and she was admitted to our hospital for tocolysis. After admission, she was referred to our antenatal diagnostic clinic for a routine examination of the fetus. Real­-time ultrasound revealed an appropriately growing fetus (biparietal diameter: 82 mm; abdominal perimeter: 255 mm; femur length: 56 mm and estimated weight: 1,5l0g).

Echocardiography showed mild downward displacement of the tricuspid valve into the right ventricle (fig. 1).

Fig. 1: Four-chamber view of the heart shows a mild downward displacement of the tricuspid valve into the right ventricle. LA = left atrium, LV = left ventricle, RA = right atrium, RV = right ventricle, MV = mitral valve, TV = tricuspid valve.

However, right atrial enlargement and cardiomegaly were not evident. Color and pulsed Doppler ultrasound showed turbulent regurgitant flow from right ventricle to right atrium in systole (fig. 2).

Fig. 2: Color and pulsed Doppler ultrasound showing turbulent regurgitant flow from the right ventricle to the right atrium in systole.

Therefore, the antenatal diagnosis of Ebstein anomaly was made. Associated anomalies were not recognized. During gestation, there was no sign of cardiac failure. Pulsatility index values of middle cerebral artery, descending aorta, renal artery and umbilical artery were within normal ranges¹².At 37 weeks" gestation, a male baby weighing 2594g was delivered vaginally. The Apgar scores were 8 and 9 at 1 and 2 minutes. Postnatal echocardiography and angiocardio­graphy confirmed the antenatal diagnosis. At this writing, the child is alive and doing well. He is under monthly observation at our pediatric clinic and requires no medication.

Discussion

Embryology

Embryologically the tricuspid valve cusps are primarily derived from the interior of the embryonic right ventricular myocardium. The inner layer of ventricular myocardium is freed from the remainder of the right ventricular wall and forms a muscular skirt. The atrial side of the skirt near the atrioventricular orifice is partially covered by endocardial cushion tissue¹⁵.

Pathogenesis

The atrioventricular valve forms by undermining of the endocardium in the 13-16mm embryo. Ebstein anomaly results from a failure of this mechanism.

Associated anomalies

Atrial septal defect (secundum type or patent foramen ovale), pulmonary atresia or stenosis, patent ductus arteriosus, tetralogy of Fallot, coarctation of the aorta, atrioventricular canal, and transposition of the great vessels are possible associated anomalies².

Diagnosis

The main criterion for the antenatal diagnosis of Ebstein anomaly is the demonstration of downward displacement of the tricuspid value into the right ventricle. The right atrium is generally extremely enlarged¹³. In our case, the displacement of the tricuspid value was not so remarkable, and enlargement of the right atrium was not evident.

The conventional two-dimensional echocardiographic findings were not confirmative. Doppler color flow mapping reveals precise abnormal intracardiac hemodynamics in various congenital heart diseases which are almost consistent with postnatal Doppler echocardiographic and angiographic findings^8,9,11. The clinical benefits of color flow mapping are significant when this technique is compared with the use of conventional real-time instruments alone^10,11.

We conducted color Doppler examination for confirmation of suspected fetal cardiac anomaly, and typical tricuspid regurgitation was identified. Consequently, the antenatal diagnosis of Ebstein anomaly was made.

Differential diagnosis

The differential diagnosis include tricuspid insufficiency without displacement, Uhl anomaly, and pulmonary atresia with intact ventricular septum and tricuspid insufficiency.

Prognosis

In the absence of tricuspid regurgitation, this condition may be completely asymptomatic. Such patients do not develop symptoms until adolescence or adult life. On the other hand, symptomatic newborns often develop congestive heart failure³.

Information on the natural history of Ebstein anomaly, based on an experience of 67 patients, was provided by Giuliani et al⁴. Mortality in this series was found to be affected primarily by four factors: New York Heart Association class III or IV; cardio­megaly; cyanosis or hypoxia; and diagnosis in infancy⁴.

Management

When the diagnosis is made before viability, the option of pregnancy termination should be offered. A careful search for associated cardiac and extracardiac anomalies, including karyotype, is recommended for all cases.

Serial ultrasound examination should be performed to search for signs of congestive heart failure. The association of hydrops with a structural cardiac defect is an ominous combination. The optimal management of these patients has yet to be established. In the absence of congestive heart failure, there is no indication to alter standard obstetrical management, but delivery in a tertiary care center where a pediatric cardiologist is immediately available is mandatory³.

References

1. Nora JJ, Nora AH. Genetics and genetic counseling in cardiovascular disease. Springfield: Charles C Thomas, 1978.

2. Becker AE, Anderson RH. Pathology of congenital heart disease. London: Butterworths, 1981.

3. Romero R, Pilu G, Jeanty P et al. Prenatal diagnosis of congenital anomalies. Norwalk: Appleton & Lange, 1988.

4. Giuliani ER, Fuster V, Brandenburg RO, Mair DD. Ebstein"s anomaly. The clinical features and natural history of Ebstein"s anomaly of the tricuspid valve. Mayo Clin Proc 54:163-165,1979.

5. Hata T, Yamamoto K, Kitao M. Prenatal fetal heart structures identified by two-dimensional echocardiogr-aphy. Asia-Oceania J Obstet Gynaecol 9:37-42,1983.

6. Hata T, Yamamoto K, Kitao M, Kajino Y. Antenatal diagnosis of congenital complicated heart anomalies: Case report. Cardiovasc Ultrasonog 2:391-394,1983.

7. Benacerraf BR, Pober BR, Sanders SP: Accuracy of fetal echocardiography. Radiology 165:847-849, 1987.

8. Hata T, Senoh D, Aoki S, Hata K, Takamiya 0, Kitao M. Doppler colour flow mapping of partial atrioventricular septal defect in utero. J Obstet Gynaecol 9:281-282, 1989.

9. Hata T, Ilata K, Makihara K, Eda Y, Kitao M. Hypoplastic left heart syndrome: Color Doppler flow mapping. The Fetus 1:7467 1-3,1991.

10. Hata T, Hata K, Ryukoh K, Aoki S, et al. Fetal cardia hemodynamics assessed by two-dimensional Doppler echocardiography. Asia Oceania J Obstet Gynaecol 14:111-115, 1988.

11. Chiba Y, Kanzaki T, Kobayashi H, Murakami M, et al. Evaluation of fetal structural heart disease using color flow mapping. Ultrasound Med Biol 16:221-229, 1990.

12. Arduini D, Rizzo G. Normal values of pulsatility index from fetal vessels: A cross-sectional study on 1556 healthy fetuses. J Perinat Med 18:165-172,1990.

13. Reed KL, Anderson CF, Shenker L. Fetal echocardiography: An atlas. New York: Alan R Liss, Inc., 1988.

14. James J, Nora J (Eds.): Tricuspid valve, Ebstein anomaly. in Birth Defect Encyclopedia, Dover, MA, Blackwell Scientific Publications.  p 1707, 1990.

15. Adams FH, Emmanouilides GC. Heart disease in infants, children, and adolescents. Baltimore: Williams & Wilkins, 1968.