Cor Triatriatum Dexter Mimicking Ebstein Disease
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 ventricle and covering nearly completely the tricuspid valve leaflets (Figure 4 and Movie I in the online-only Data Supplement). Doppler analysis showed low diastolic flow velocities across the membrane and tricuspid valve. In systole, the huge membrane was flowing back toward the right atrium (Movie II in the online-only Data Supplement). The right ventricular cavity was slightly shortened in the long axis, but flow across the pulmonary valve was unobstructed.
The child was operated on the next day. Under cardiopulmonary bypass, the right atrium was opened and exposed. A large patent foramen ovale was completely surrounded by an aneurysmal eustachian valve, up to the superior limbus over the aortic root and tethered to the terminal crest and interatrial groove by thin filaments (Figures 5 and 6⇓), directing the inferior vena cava flow directly to the left atrium (Figure 7). The membrane could be invaginated completely into the right ventricle, creating a right inflow obstruction. After membrane excision, the tricuspid valve appeared normal in size and morphology. The foramen ovale was closed. Her postoperative course was uneventful. She was extubated on day 2, normalized her oxygen saturations on day 5, and was discharged home on day 10 with no medication. Two months after surgery, she is thriving normally and is fully saturated. Echocardiogram shows normal intracardiac anatomy with an unobstructed right atrium and normal movement of the tricuspid valve leaflets (Movie III in the online-only Data Supplement).
The divided right atrium or cor triatriatum dexter is a rare anomaly. It is caused by persistence of the right valve of the sinus venosus, which partitions the right atrium into 2 chambers: the trabeculated portion with the tricuspid valve and the sinus venarum receiving the inferior and superior vena cava.1 Normally, the right valve regresses early during fetal life, leaving behind the crista terminalis superiorly and the eustachian valve of the inferior vena cava and the thebesian valve of the coronary sinus inferiorly. Clinical manifestations may vary depending on the degree of septation of the right atrium. When the septation is incomplete, the patient is often asymptomatic, and the diagnosis is often an incidental finding or even made postmortem. If the septation is severe, symptoms may be severe and fatal because of obstruction of the tricuspid valve or the inferior vena cava. Associated intracardiac lesions may occur, including interatrial defects and Ebstein anomaly of the tricuspid valve.1,2 Diagnosis usually relies entirely on echocardiography. Antenatal diagnosis is now also possible.3 Surgery is highly successful in symptomatic patients by removing entirely the obstructive membrane.4
Our case shows, however, that clinical presentation and echocardiography can be confusing. The “spinnaker” movement of the pretricuspid membrane covered the tricuspid valve entirely during diastole, mimicking the abnormal movement and placement of an Ebstein-type tricuspid valve. Detailed and slow-motion analysis allowed us to differentiate the membrane from the leaflets and ensure that the tricuspid valve morphology and motion were completely normal.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/cgi/content/full/120/11/e86/DC1.
Gerlis LM, Anderson RH. Cor triatriatum dexter with imperforate Ebstein’s anomaly. Br Heart J. 1976; 38: 780–782.
Eroglu ST, Yildirir A, Simsek V, Bozbas H, Bilgi M, Ozin B, Muderrisoglu H. Cor triatriatum dexter, atrial septal defect, and Ebstein’s anomaly in an adult given a diagnosis by transthoracic and transesophageal echocardiography: a case report. J Am Soc Echocardiogr. 2004; 17: 780–782.