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Surgical resection of an obstructive Chiari Network.

A girl born at 36 weeks gestation weighing 2.03 kg, was transferred to our hospital because of supraventricular tachycardia. Echocardiogram showed a small secundum atrial septum defect which shunted mainly right to left and a prominent Chiari network. There was no tricuspid valve regurgitation or stenosis. The right ventricular end diastolic dimension, pulmonary valve, and tricuspid annular diameter were normal for body surface area. Surprisingly by the third week of life, the infant became increasingly cyanotic with oxygen saturations between 75% and 80%, requiring supplemental oxygen. Repeat echocardiography demonstrated an exclusive right to left shunt at atrial level (see supplementary data online, Video S1). The Chiari network appeared to prolapse through the tricuspid valve orifice causing mild flow acceleration with a mean gradient of 3 mmHg in the presence of an atrial septal defect (see supplementary data online, Videos S2-S4). Repeated attempts to wean oxygen were unsuccessful, therefore the decision was made to surgically resect the obstructive Chiari network. The Chiari network was resected, in addition to resection of right ventricular muscle bundles and a creation of an adjustable atrial septal defect. After surgery, the infant maintained normal oxygen saturations at discharge. Postoperative echocardiogram showed laminar flow across the tricuspid valve with no regurgitation and left to right shunting across a small residual atrial septal defect. The Chiari network usually carries little clinical significance, however it has been associated with cyanosis, paradoxical emoboli, thrombus formation, and endocarditis. Cyanosis is usually transitory as the Chiari network often spontaneously regresses. Usually, surgical intervention is only necessary for persistent cyanosis or persistent obstruction resulting in underdevelopment of right sided heart structures.