Cortazar Rocandio, GonzaloYague Martin, MartaTejero Hernandez, Maria AngelesMerino Cejas, CarlosCasares Mediavilla, JaimeGomez Guzman, Elena2023-05-032023-05-032022-04-081134-0096http://hdl.handle.net/10668/22091The circular shunt is a situation in which there is a circuit where the blood reaches the same cardiac chamber without passing through the pulmonary or systemic capillary bed.This shunt is possible in patients associated with pulmonary stenosis (PS), tricuspid regurgitation (TR), ventricular septal defect (VSD), and patent foramen ovale (PFO) or atrial septal defect (ASD). It has also been described in patients with pulmonary atresia with intact septum (PAIS) who present with pulmonary insufficiency (PI) after surgical or percutaneous opening of the pulmonary valve (PV), TI and presence of a ductus (PDA) or a systemic pulmonary fistula (PSF) and in patients with Ebstein's anomaly with moderate-severe PI.We present three clinical cases of patients with congenital heart disease who developed a circular shunt during their evolution, two patients presented an PAIS, presenting the corresponding symptoms after opening the PV, and the remaining one an Ebstein's anomaly with pulmonary insufficiency that presented the shunt circular at birth.In conclusion we can say that the circular shunt is an entity little described in the bibliography, but with a very important severity and mortality. Right ventricular (RV) dysfunction, which generates less antegrade flow through the pulmonary artery, appears to be one of the most important factors for its development.We must be aware of this situation and have access to an emergency surgical team capable of interrupting this surgery by closing/banding the ductus arteriosus or fistula, or by means of palliative surgery for underlying heart disease. (C) 2022 Sociedad Espanola de Cirugia Cardiovascular y Endovascular. Published by Elsevier Espana, S.L.U.esAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/Circular shuntPulmonary atresiaEbstein's anomalyCongenital heart diseaseresearch articleopen access10.1016/j.circv.2021.11.002https://doi.org/10.1016/j.circv.2021.11.002821881600012