2.1.1 Systemic to pulmonary arterial shunts are surgically created connections between the aorta and a pulmonary artery in children with cyanotic congenital heart disease, such as tetralogy of Fallot or tricuspid atresia. The shunts increase the blood supply to the lungs and the arterial oxygen saturation. The procedures are palliative. In some children, definitive surgery may be possible later. The most common type of systemic to pulmonary shunt is known as the Blalock–Taussig shunt.
2.1.2 Systemic to pulmonary shunts may become blocked or narrowed (stenosed) because of scarring or thrombosis. Stenosed systemic to pulmonary shunts may be treated by a repeat surgical systemic to pulmonary shunt operation.
2.2.1 Balloon dilatation of systemic to pulmonary shunts is a palliative procedure carried out to relieve blockage or narrowing of pulmonary shunts. The procedure involves inserting a catheter into a large blood vessel (usually in the groin), passing it up into the chest under radiological guidance and inflating a balloon in the narrowed area. This may avoid the need for a repeat surgical systemic to pulmonary shunt procedure.
2.3.1 The evidence was limited to small uncontrolled case series. All these studies reported increases in mean oxygen saturation, ranging from 5% to 19%. One of the studies reported successful dilatation (> 20% increase in oxygen saturation) in 91% (42/46) of patients. For more details, refer to the Sources of evidence section.
2.3.2 The Specialist Advisors had no concerns regarding the efficacy of this procedure.
2.4.1 Adverse events were poorly reported in the largest study, which included 46 people. The main adverse events reported in the next largest studies included: one patient with pulmonary hypertension and one death because of pneumonia (could not be weaned off ventilator) in a study of eight patients; and one patient with a thrombosed femoral artery, one patient with balloon rupture and one case of severe arterial vasospasm in a study of six patients. For more details, refer to the Sources of evidence section.
2.4.2 Potential adverse events noted by the Specialist Advisors included tearing of the vessel or shunt, death, complete shunt occlusion, rupture, thrombosis, haemorrhage, embolic stroke, and pulmonary embolism.