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Correspondence to: Dr. Kevin P Morris Paediatric Intensive Care Unit, Birmingham Children’s Hospital NHS Trust, Steelhouse Lane, Birmingham, B4 6NH, United Kingdom; [email protected]
Hypoplastic Left Heart Syndrome (HLHS) describes a group of cardiac anomalies characterised by underdevelopment of the left side of the heart with severe hypoplasia of the ascending aorta. In 1983 Norwood first described a series of infants who underwent successful surgical palliation using a staged approach.1 Cardiac centres still quote mortality rates between 5 and 40% following the Norwood procedure.2
As the native main pulmonary artery is used in the construction of a neoaorta during the Norwood procedure an alternative source of pulmonary blood flow becomes necessary. Traditionally, the pulmonary circulation following the Norwood procedure has been supplied by a modified Blalock Taussig (BT) shunt, with a GORE-TEX tube connecting the subclavian artery and the pulmonary artery. BT shunt flow to the lungs occurs throughout the cardiac cycle, resulting in potential ‘steal’ from the systemic circulation during diastole. Furthermore coronary perfusion following the Norwood procedure is usually dependent on retrograde flow down a diminutive ascending aorta and can potentially be compromised by diastolic run-off and a low diastolic pressure.
In 2003 Sano and colleagues reported a modification of the Norwood procedure by placing a larger GORE-TEX graft between the right ventricle and the pulmonary arteries.3 This right ventricle to pulmonary arteries (RV to PA) conduit has been proposed as a better alternative to a modified BT shunt and preliminary data from one or two centres has suggested a better outcome.4–6 It is hypothesized that the conduit will provide a more stable post-operative balance between pulmonary and systemic circulations with a lower pulmonary:systemic blood flow ratio (Qp/Qs). Improved coronary perfusion as a result of less diastolic run-off may improve myocardial performance. On the other hand creation of an RV-PA conduit may require a longer aortic cross-clamp time and involves an incision into the right ventricular muscle, a ventriculotomy, both of which may adversely affect myocardial function in the post-operative period.
We undertook this study is to compare early postoperative haemodynamic data and markers of pulmonary and systemic blood flow between patients undergoing a Norwood procedure with a modified BT shunt or an RV-PA conduit.
METHODS
At Birmingham Children’s...