The RV-PA conduit stimulates better growth of the pulmonary arteries in hypoplastic left heart syndrome.

OBJECTIVE: This retrospective study compared the size of the central pulmonary arteries in patients with hypoplastic left heart syndrome (HLHS) following either a classical Norwood or Norwood procedure with a right ventricle to pulmonary artery (RV-PA) conduit.

METHODS: Between May 2001 and May 2003, 30 patients with HLHS underwent cardiac catheterization prior to stage II palliation. Patients were initially palliated with a classical Norwood (Classical group, n=18) or Norwood procedure with RV-PA conduit (RV-PA group; n=12). Indexed maximum and minimum diameters of the LPA and RPA were measured using the McGoon ratio. Cardiac catheterisation was performed at a median age of 4.0 months. There was no difference in the time interval to catheterisation (P=0.13), Qp:Qs (P=0.41) or median haemoglobin (P=0.42) between the groups.

RESULTS: The combined PA diameter was larger in the RV-PA group (B) than the classical group (A) (1.99+/-0.38 versus 1.63+/-0.29, P<0.05). There were marked differences in the relative size of the pulmonary arteries between the two groups. In RV-PA patients, the LPA and RPA sizes were comparable (0.99+/-0.22 versus 1.00+/-0.31, P=1.00) whereas, in the classical group, the LPA was smaller than the RPA (0.75+/-0.15 versus 0.88+/-0.17, P<0.05). Both techniques were also associated with discrete PA stenoses at the site of shunt insertion. Stenoses were more severe in RV-PA group (RV-PA), causing a 42+/-16% reduction in the combined PA diameter compared with a 28+/-18% reduction in Classical group (classical) (P<0.05).

CONCLUSIONS: The Norwood procedure with RV-PA conduit is associated with better and more evenly distributed central pulmonary artery growth. Nevertheless, it is also associated with central PA stenoses, which may require subsequent reconstruction.