**3.1. Perinatal period**

two zones, with an "atrialized" poorly functional portion between the true annulus and the hinge point of the apically displaced septal leaflet, while the "functional" RV is the portion below the leaflet hinge point. Depending on the degree of leaflet displacement this functional

The clinical manifestations of EA vary widely from mild forms presenting in adulthood, to severe forms with high mortality in the neonatal period. In utero, EA can result in hydrops and arrhythmia. Furthermore, an in utero diagnosis of EA has an incidence of 48% fetal demise [3]. Mortality rates are highest in the neonatal period ranging from 17 to 56% [4] and

Ebstein anomaly is known to have several additional cardiac manifestations. A patent foramen ovale or atrial septal defect is normally present. The right to left shunting across the defect accounts for the relative hypoxia exhibited in certain patients. RV outflow tract obstruction in the form of anatomical pulmonary atresia occurs in about half of the symptomatic neonates requiring surgical intervention [5]. In the setting of pulmonary atresia, a patent ductus arteriosus is required as the source of pulmonary blood flow [6–8]. Left ventricular non-compaction cardiomyopathy has been noted to be associated with EA. A retrospective study demonstrated that 10 of 61 patients (16%) with EA also had left ventricular non-compaction [7]. This was associated with a higher mortality risk of 30% in those with LVNC compared to 13% with EA alone. Wolff-Parkinson-White (WPW) is present in about 10–30% of cases. In about 20% of cases with WPW, there may be more than two accessory pathways present. The accessory pathways are usually present on the tricuspid valve annulus [9, 10]. Due to large right atrium, EA patients are at risk for atrial tachycardia, atrial flutter, intra-atrial reentrant tachycardia, atrial fibrillation, AV node reentrant tachycardia, and

Carpentier et al. described the characteristic features of this disorder that are relevant to surgi-

**1.** Failure of delamination of the TV leaflets is the hallmark of EA whereby the leaflets are tethered to the endocardium by fibromuscular attachments or abnormal foreshortened chordae. Each leaflet exhibits varying degrees of apical displacement and tethering with the septal leaflet most severely affected followed by posterior then anterior leaflets. This

**2.** The anterior leaflet is attached to the true anatomical annulus but is large or sail like.

results in anterior and apical displacement of the functional annulus.

RV volume can be quite diminutive.

150 Congenital Anomalies - From the Embryo to the Neonate

ventricular arrhythmias.

**3. Pathologic anatomy**

cal management [11].

poses significant medical and surgical challenges.

**2. Associated anomalies and arrhythmias**

The long term prognosis of a fetus diagnosed with EA is poor and remains one of the highest mortalities amongst congenital heart disease patients. One multicenter study showed that a fetal diagnosis of EA resulted in a 17% fetal demise. Furthermore, there was an additional 32% in-hospital attrition of live-born babies with EA with an overall 45% perinatal mortality [4]. Risk factors for perinatal mortality include lack of antegrade flow across the pulmonary valve, large cardiothoracic ratio, earlier in utero diagnosis, large tricuspid valve annulus, pericardial effusion, and right ventricular dysfunction [13–16]. Pulmonary valve regurgitation may be the most ominous risk factor representing the end result of severe tricuspid regurgitation with resultant volume load on a myopathic right ventricle that has to pump against retrograde flow from the PDA. This triad of diminished preload, increased afterload and a dysfunctional right ventricle leads to inadequate preload to the left ventricle and subsequent heart failure, cardiogenic shock and perinatal demise. These factors in-utero lead to hydrops and arrhythmias and ultimately fetal demise.
