Cor Triatriatum Dexter Mimicking Ebstein Disease

Abstract

A 4-month-old girl was referred for cyanosis and echocardiographic suspicion of Ebstein anomaly. Medical history had been uneventful thus far. At clinical examination, she was restless and cyanosed but did not show respiratory distress, cardiac failure, or failure to thrive. Cardiac and lung auscultation were normal except for tachycardia (150 to 180 bpm). Femoral pulses were present. Oxygen saturation on pulse oximetry oscillated between 55% and 70%. ECG showed abnormal right atrial hypertrophy (Figure 1). Chest x-ray showed no cardiomegaly but reduced pulmonary blood flow (Figure 2). Repeat echocardiography showed normal situs and connections. There was a large patent foramen ovale with mainly right to left shunt. The tricuspid valve annulus size was normal (13.1 mm; Z score=+0.2). First images suggested a restrictive opening of the tricuspid valve, which appeared shifted toward the apex, as seen in Ebstein disease (Figure 3). There was, however, hardly any tricuspid valve regurgitation. Close analysis showed normal insertions of the leaflets, precluding the diagnosis of Ebstein disease. Slow-motion analysis showed during diastole a very large and thick membrane arising from the right atrium, protruding toward the right …