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.................................................................... static sports. Patients with severe PS should be restricted to lowintensity sports. • Pregnancy: well tolerated unless the RVOTO is extremely severe or unless RV failure is a major issue. Transcatheter balloon valvotomy can be performed during pregnancy but is rarely necessary (see section 3.5.7). • IE prophylaxis: recommended only for high-risk patients (see section 3.4.6).

4.9 Ebstein anomaly

4.9.1 Introduction and background Ebstein anomaly is characterized by abnormally formed and apically displaced leaflets of the TV. The anterior leaflet usually originates at the annular level but is enlarged and sail-like, while the septal and posterior leaflets are displaced towards the RV apex and often tethered to the endocardium. The apical displacement of the TV means that the right heart consists of a morphological RA, an atrialized portion of the RV, and the remaining functional RV; the TV is often regurgitant. The most frequently associated anomalies include a shunt at the atrial level [secundum ASD or patent foramen ovale (PFO)] and (concealed) accessory pathways, including Mahaim-type pathways. Multiple accessory pathways in conjunction with AT and AF are associated with SCD. Ebstein-like anomaly of the systemic TV is present in one-third of ccTGA.

Haemodynamic changes depend on the severity of the TV dysfunction, the degree of atrialization of the RV, contractility of the remaining functional RV and the systemic ventricle, type and severity of concomitant anomalies, and arrhythmias. The pathophysiology is characterized by systolic regurgitation of blood from the functional RV, across the TV, and into the atrialized ventricle or RA, which tend to dilate. An interatrial connection permits a LR shunt or, especially during exercise, a RL shunt. Ebstein anomaly may result in a chronically low systemic cardiac output.

4.9.2 Clinical presentation and natural history The clinical presentation ranges from trivial symptoms to the presentation of a profound cyanotic heart defect. Patients with mild forms can be asymptomatic over decades until they are diagnosed. Typical complications include high-grade TR, RV dysfunction, RV failure, liver cirrhosis, cerebral abscesses, paradoxical embolism, pulmonary embolism, tachyarrhythmias, SCD, and IE. Key symptoms are arrhythmias [atrioventricular reentrant tachycardia (AVRT) is most

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Figure 7 Management of right ventricular outflow tract obstruction. ASD = atrial septal defect; PS = pulmonary stenosis; RL = right-to-left; RV = right ventricle/ventricular; RVOTO = right ventricular outflow tract obstruction; RVSP = right ventricular systolic pressure; TR = tricuspid regurgitation; VSD = ventricular septal defect. aIn peripheral PS, regardless of symptoms, catheter interventional treatment should be considered if >50% diameter narrowing and RVSP >50 mmHg and/ or related reduced lung perfusion is present. bIn valvular PS, balloon valvuloplasty is the intervention of choice if anatomically suitable. Downloaded from academic.oup.com/eurheartj/article/42/6/563/5898606 by guest on 07 October 2026