Cor triatriatum dexter: rare case of neonatal cyanosis

Abstract

Cor triatriatum dexter is a very rare cardiac anomaly in which a membrane divides the right atrium into two chambers [1]. Depending on the degree of right atrial obstruction, the clinical sign of these anatomic variations may be neonatal cyanosis necessitating urgent surgical intervention; some patients are asymptomatic and reach adulthood without therapy [2]. Echocardiographic diagnosis can be difficult [1, 3]. We report on a newborn referred for severe neonatal cyanosis with the diagnosis of cor triatriatum dexter with obstruction of the right ventricular inflow. Surgical intervention led to complete recovery. The male neonate was spontaneously born at 41 weeks of gestation after an uncomplicated pregnancy with a birth weight of 3550 g. After the initial uncomplicated situation, central cyanosis with a transcutaneous oxygen saturation of 85% led to admission to the neonatal intensive care unit. The echocardiographic evaluation revealed a large, floating membrane within the right atrium connected to the eustachian and thebesian valve at the site of the connection to the inferior vena cava and the atrial septum, respectively, without hemodynamic compromise, but with right-to-left shunting through the secundum atrial septal defect. The membrane formed a ‘‘windsock’’ especially in diastole when it was bulging into the right ventricular inflow tract. Laterally, there was an opening within the membrane permitting turbulent blood flow from the right atrium to the right ventricle (mean pressure gradient 2 mmHg). Surgery was performed then at the age of 4 weeks in a stable patient. After an oblique right atrial opening the membrane was exposed with its attachments to the eustachian valve, thebesian valve, and laterally to the crista terminalis. There were no attachments to the interatrial septum. The membrane could be invaginated completely into the right ventricle, creating an inflow obstruction. The tricuspid valve was normal. The membrane was completely excised and the atrial septal defect (secundum type) was closed directly. The postoperative course was uneventful and the patient was extubated on the day of surgery and discharged home on the 13th day after surgery. Remnants of the right valve of the embryonic sinus venosus are not uncommon and are recognized as the normal eustachian and thebesian valves [3]. In a series of 300 consecutively autopsied patients, almost 70% of the specimens presented such valves [4]. Clinical manifestation of cor triatriatum dexter includes a wide spectrum. It can be completely asymptomatic and detected incidentally or at necropsy. During fetal life, marked nuchal edema may be associated with significant obstruction of the right ventricular inflow [5]. Also, significant obstruction may lead to the underdevelopment of the right heart structures: tricuspid valve abnormalities including Ebstein anomaly, hypoplastic right ventricle and pulmonary stenosis or atresia. After birth, neonatal cyanosis may appear due to the systemic venous blood flow directed toward the atrial septum and consecutively right-to-left shunting [1]. In the M. Loeff R. Kozlik-Feldmann H. Netz R. D. Pozza (&) Department of Pediatric Cardiology, Klinikum Groshadern, Ludwig-Maximilians-University, Marchioninistr. 15, 81377 Munich, Germany e-mail: Robert.DallaPozza@med.uni-muenchen.de