the bidirectional cavo-pulmonary anastomosis is a well-established palliative procedure for patients with a functionally univentricular circulation. it is usually considered one step in preparation for fontan procedure, but it may be performed as a long-term palliation for patients deemed to be at high-risk. in this subset of patients, a valuable surgical option could be to add, or maintain, an additional source of flow of blood to the lungs, either derived from a patent but banded trunk or one protected by native pulmonary stenosis, or a systemic-to-pulmonary arterial shunt. the risk and benefits of providing an additional source of pulmonary flow after construction of a bidirectional cavopulmonary anastomosis are strongly debated. in terms of benefit, the arterial saturation of oxygen is increased due to the greater ratio of pulmonary-to-systemic flow, arteriovenous fistulas are prevented and, as a consequence of the arterial pulsatile flow, the pulmonary arteries are stimulated to grow. the most significant drawbacks are volume overload of the functionally single ventricle, and higher pressures compared to an isolated bidirectional cavopulmonary anastomosis.