Right-to-left shunt from systemic venous to pulmonary venous system developing after SVC obstruction

This report and review of the literature describe a rare form of right-to-left shunt found in patients with superior vena cava (SVC) obstruction. Following SVC obstruction, collateral vessels may develop between the systemic venous system and the pulmonary venous system causing the alveolar space and right heart to be bypassed. Perception of this unusual shunting of blood on enhanced chest CT may help explain clinical symptoms of hypoxia.