Prominent prolapsing Chiari network: presentation and prognosis in paediatric patients

Chiari network is an infrequently visualized web-like structure in the right atrium that is usually thin and small. Rarely, it can be prominent and elongated with protrusion into the right ventricle during diastole and complications have been reported. Thirty-eight patients (median age 2.5 years) with prolapsing Chiari network were identified and associated cardiac abnormalities documented. Echocardiographic right and left heart parameters were measured and compared to normative data. At presentation, the extent of Chiari network prolapse below the tricuspid annulus was 9.1 ± 3.5 mm (mean ± standard deviation), mean pulmonary valve annulus diameter z-value was reduced (-0.91 ± 0.64), and mean aortic valve z-value was enlarged (+0.97 ± 0.87). Fourteen patients exhibited no other cardiac abnormality. Eight were noted to have atrial septal defects, eight demonstrated supraventricular dysrhythmias, six had mild to moderate tricuspid valve regurgitation, and one patient each had an atrial septal aneurysm, severe pulmonic valve stenosis, small perimembranous ventricular septal defect, bicuspid aortic valve, and mild right upper pulmonary vein stenosis. Fourteen patients (37%) were seen in follow-up from 1 to 8.5 years later (median 3.2 years). During that time, the magnitude of prolapse across the tricuspid valve decreased by up to 7 mm (median 2 mm). Interventions were required in three patients, but many associated cardiac abnormalities resolved spontaneously with growth. Thus, the presence of a prolapsing Chiari network has a substantial risk of associated CHDs. However, the extent of Chiari network prolapse gradually decreases and many related abnormalities resolve during growth.

Benign Structures Mimicking Right Atrial Masses on Prenatal Ultrasound

Advances in imaging have resulted in more frequent reporting of primitive right atrial structures which can sometimes mimic cardiac tumors in prenatal ultrasound. Prominent crista terminalis and Chiari network are examples of these structures. We describe two cases of pregnant women referred to the fetal cardiology clinic for fetal echocardiography for right atrial masses seen on prenatal ultrasound suspicious of tuberous sclerosis. The first case subsequently diagnosed as crista terminalis and the second case as a prominent Chiari network. Postnatal ECHO confirmed the benign nature of these structures. It is important to differentiate tumors from prominent benign structures in the right atrium in fetal ECHO. The location and the similar echogenicity to the adjacent atrial tissue are clues for differentiation of these structures from atrial tumors.