Norwood procedure for hypoplastic left heart syndrome: BT shunt or RV-PA conduit?

Background: The Norwood procedure is the first stage palliative procedure for hypoplastic left heart syndrome (HLHS). Traditionally the pulmonary circulation has been supplied via a modified Blalock Taussig (BT) shunt but a recent modification, adopted in some UK centres, substitutes a conduit between right ventricle and pulmonary arteries (RV-PA conduit). It is argued that this will result in a more favourable balance between pulmonary and systemic circulations. Aim: To compare the early postoperative haemodynamic profile between patients undergoing a BT shunt or an RV-PA conduit. Methods: Retrospective review in a tertiary referral PICU of 51 children with HLHS undergoing the Norwood procedure with either a BT shunt (Group 1; n = 23) or an RV-PA conduit (Group 2; n = 28). Data items were extracted at 10 set time points in the initial 96 h, postoperatively. Results: Diastolic BP was significantly lower in Group 1 (p < 0.001) with a trend towards a higher systolic BP and no difference in mean BP. No between-group differences were found in markers of pulmonary blood flow (PaO2, PaCO2, PaO2/FiO(2) ratio), or in markers of systemic blood flow (blood lactate, oxygen extraction ratio), or in estimated ratio of pulmonary: systemic blood flow (Qp:Qs). Despite lower diastolic blood pressure in Group 1 renal and hepatic function did not differ over five post-operative days between groups. Conclusions: With the exception of a higher diastolic blood pressure in the RV-PA conduit group, we found no difference in the early haemodynamic profile between patients undergoing an RV-PA conduit or a BT shunt.