2 The procedure
2.1.1 This procedure is undertaken to relieve the symptoms of cyanotic congenital heart disease by improving the flow of oxygenated blood to the systemic circulation. There are several types of cyanotic congenital heart disease for which this procedure is indicated. Among these is transposition of the great arteries, an uncommon congenital cardiac anomaly in which the aorta arises from the right ventricle and the pulmonary trunk arises from the left ventricle. This results in two separate circuits of blood flow, in which highly oxygenated blood recycles through the lungs, while oxygen-depleted blood recycles around the body. As a result, the baby develops a blue colour (cyanosis) shortly after birth. The baby can survive for a few days because the foramen ovale (a small hole in the fetal interatrial septum) allows some oxygenated blood to mix with the blood that is being recirculated around the body. However, the foramen ovale normally closes days after birth, and the only babies then likely to survive are those with a congenital ventricular septal defect.
2.1.2 There is no reliable alternative to septostomy procedures in babies.
2.2.1 Endovascular atrial septostomy is a procedure that is used to enlarge the foramen ovale. A catheter is passed through a large vein, usually in the groin, into the right atrium and through the foramen ovale to the left atrium. In simple balloon septostomy, a balloon at the end of the catheter is inflated and pulled back into the right atrium, so enlarging the foramen ovale. When this procedure is unsuccessful or contraindicated, static balloon atrial septostomy is used to enlarge an inter-atrial communication. The septum is cut using a catheter with a blade at its end. The balloon is then used to enlarge the opening in the septum. The procedure aims to prolong survival until definitive surgery can be performed.
2.3.1 No controlled studies were identified and many of the studies found were published more than 15 years ago. One of the studies reported an 'immediate haemodynamic effect' in 95% (508/535) of patients. Another reported a mean increase in arterial oxygen saturation of 21%; two other studies reported increases of 21% and 16% in median systemic arterial oxygen saturation. For more details, refer to the Sources of evidence section.
2.3.2 The Specialist Advisors regarded this procedure as established practice. They also noted that the septostomy may close spontaneously, necessitating surgical septectomy.
2.4.1 Among the identified studies, mortality from the procedure ranged from 2% (2/104, 3/149) to 3% (3/108). One study reported a minor complication rate of 10% (26/248) and a lethal complication rate of 1% (3/248). For more details, refer to the Sources of evidence section.
2.4.2 The Specialist Advisors considered the main safety concerns to be death, transient arrhythmias and cardiac injuries.
2.5.1 This procedure has become established as a life-saving measure for severely ill neonates, but clinical trial data are very limited.
2.5.2 The majority of the evidence relates to the simple balloon method.
2.5.3 The evidence on static balloon atrial septostomy is more limited.