Unusually prominent Chiari's network prolapsing into the right ventricle in an asymptomatic newborn.

Chiari's network (CN) is an embryologic remnant of eustachian valve located in the right atrium (RA). Incomplete involution of the fetal sinus venosus valves results in ''redundant'' CN. CN has been found in 1.3-4 % of autopsy studies and is believed to be of little clinical consequence. However, a redundant CN may favor persistence of a patent foramen ovale, formation of an atrial septal aneurysm, atrial thrombus, or paradoxic embolism, or cause intense right-to-left shunting. It may also cause arrythmias or compromise cardiovascular functions. We report an asymptomatic newborn with a prominent CN prolapsing into the right ventricle and discuss the clinical consequences of a CN. Although the patient herein presented is asymptomatic, CN may cause persistent cyanosis in the newborns mimicking congenital heart disease. It can also be confused with other curvilinear, highly mobile pathologic structures in the RA, such as vegetation, flail tricuspid leaflet, ruptured chordae tendinae, thrombus, or tumor. CN is not always a benign structure; therefore, identification and accurate diagnosis by echocardiography is important.