The hybrid procedure is an alternative operation to the Norwood operation for hypoplastic left heart syndrome. It consists of pulmonary artery bands, atrial septostomy and a ductal stent. Patients are cyanotic with polycythaemia, which can cause hyperviscosity syndrome when dehydrated and coagulation problems. Anaesthesia is challenging with a R → L shunt through the duct. Saturations should be kept at 75–85%. Pulmonary blood flow is limited by the pulmonary bands, so increasing oxygen and ventilation might not result in increased saturations.