Portosystemic venous shunts occur in patients with polysplenia after the Fontan operation. In the long term, these shunts are associated with hyperammonaemia and portal-systemic encephalopathy. Since some shunts are long and tortuous, catheter interventions to close them could be challenging. Instead, a steerable microcatheter could be used for coil embolisation of tortuous portosystemic venous shunts.