2010/09/27 by G. McLean, Glenda McLean, Samuel Menahem +3
Medicine · #Cardiovascular Issues in Pregnancy #Congenital Heart Disease Studies #Coronary Artery Anomalies
paper · doi:10.1002/uog.8837
openalex publication_date 2010/09/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
A 25-year-old woman, gravida 2, para 1, was referred to our tertiary ultrasound unit at 35 weeks' gestation. She had presented late in pregnancy having no relevant past medical or family history. The fetal-anomaly ultrasound scan, performed at another center at 20 weeks, was reported to be normal, although poor views of the heart chambers were noted. A subsequent 34-week scan showed that the cardiac atria appeared to be slightly unusual and review at a tertiary center was suggested. The fetus was of appropriate size for gestational age, with normal parameters of well-being, and the remainder of the fetal anatomy was assessed as normal. A targeted fetal echocardiogram was performed in the presence of a pediatric cardiologist. A horizontal echogenic membrane-like structure was seen in the mid-cavity of the right atrium (Figure 1a). It appeared to arise from the right atrial free wall and extended towards the margin of the fossa ovalis. The valves of the inferior vena cava and coronary sinus appeared to be normal and there was laminar flow across the tricuspid valve (Figure 1b). Ultrasound images of the fetal heart at 35 weeks' gestation. (a) The four-chamber view shows an echogenic membrane (arrow) present across the right atrium. (b) Color Doppler image of the atrioventricular valves demonstrates laminar blood flow across the tricuspid valve. The findings were suggestive of cor triatriatum dexter. Given the otherwise normal structure and function of the heart it was anticipated that the lesion would have minimal, if any, hemodynamic consequences. It was recommended that the pregnancy and labor proceed as planned and the infant be reviewed shortly after birth to ensure that there was no obstructive flow into the right ventricle. A 3200-g female infant was delivered by elective Cesarean section at 39 weeks' gestation. The parents did not present her for cardiological follow-up until she was 10 months old but reported that she had been well. Echocardiography was performed and confirmed the presence of the right atrial membrane. This was not hemodynamically significant and was subsequently confirmed on a later scan (Figure 2). Postnatal echocardiographic image showing the membrane dividing the right atrium (RA). LA, left atrium. Cor triatriatum dexter is an extremely rare congenital cardiac abnormality characterized by the partitioning or septation of the right atrium to form a triatrial heart. To our knowledge prenatal diagnosis of this abnormality has not previously been reported although it has been reported on postmortem examination of a fetus1. It has also been diagnosed by echocardiography in children and adults. It is thought to arise from persistence of the right valve of the sinus venosus2. During normal development this tends to regress into the crista terminalis, the Eustachian valve of the inferior vena cava and the Thebesian valve of the coronary sinus. The clinical significance of cor triatriatum dexter depends on the degree of septation and any resultant obstruction of flow into the right atrium. If there is resultant obstruction and diversion of flow from the inferior vena cava to the left atrium through the foramen ovale it may cause cyanosis3. Cor triatriatum dexter has been associated with other heart abnormalities including interatrial defects and Ebstein's anomaly of the tricuspid valve4, 5, which may on occasion be confused with this anomaly6. An awareness of cor triatriatum dexter when scanning may help the clinician to arrive at the correct fetal diagnosis and allow for definitive counseling. G. McLean*, S. Menahem* , M. Teoh*, * Fetal Diagnostic Unit, Monash Medical Centre, Melbourne, Victoria, Australia, Fetal Cardiac Unit and Monash University, Melbourne, Victoria, Australia