Desaturation after Fontan procedure due to systemic venous collateral and improvement after closure with embolization.

A 27-year-old female patient who had operated primarily with Glenn operation and she underwent later a lateral tunnel Fontan operation. After 5 years, she presented with desaturation due to significant systemic to pulmonary venous collateral development, and a decision was made to proceed with interventional occlusion. Afterward, the arterial saturations increased.