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The Norwood Procedure Utilizing a Right Ventricle to Pulmonary Artery Conduit Promotes Balanced Pulmonary Artery Growth in Infants with Hypoplastic Left Heart Syndrome
J. D. Pruetz, S. Badran, V. A. Starnes*, A. B. Lewis. Childrens Hospital Los Angeles, University of Southern California, Los Angeles, CA,
BACKGROUND:
The Norwood procedure with right ventricle to pulmonary artery conduit (RV-PA) is thought to improve post-operative hemodynamics and decrease early mortality, but little is known about its’ effects on pulmonary artery (PA) growth. The goal of this study was to evaluate differences in PA growth of infants with Hypoplastic Left Heart Syndrome (HLHS) following a Norwood procedure with RV-PA versus modified Blalock-Taussig shunt (mBTS).
METHODS:
A retrospective review of our surgical database identified 159 patients with HLHS who underwent Norwood surgery between January 2000 and September 2005. Patients were divided into Group A if they had mBTS and Group B if they had RV-PA at the time of the Norwood. Angiograms performed at the pre-Glenn catheterization were used to obtain measurements of the pulmonary arteries and to assess for shunt/conduit stenosis (Figure 1).
RESULTS:
There were 103 patients in Group A and 56 in Group B; 10 patients were lost to follow-up (Figure 2, flow chart of patient outcomes). Group A had significantly higher thirty-day operative mortality (18/103 vs. 3/56, p=0.03) and a suggestion of higher inter-stage mortality (24/78 vs. 10/50, p=0.14) by Kaplan-Meier Survival Analysis (Figure 3). Eight Group B patients had an additional mBTS prior to Glenn surgery versus one patient in Group A (8/40 vs. 1/53, p=0.02). Pulmonary artery growth using the Nakata Index was significantly better for Group B patients that had no additional shunt placed compared to Group A patients (212 vs. 169 mm2/m2, p=0.004) and approached statistical significance for all Group B patients compared to Group A (203 vs. 169 mm2/m2, p=0.08). Right and Left PA growth was more balanced in Group B (RPA/LPA = 1.02 vs. 1.39, p=0.001) and Left PA cross sectional area was significantly greater (29 vs. 19 mm2, p=0.001). Group B patients had a higher incidence of shunt/conduit stenosis (14/32 vs. 2/32, p=0.001), lower arterial oxygen saturation prior to the Glenn (70% vs. 75.5%, p=0.002) and underwent Glenn surgery at an earlier age (192 vs. 246 days, p=0.03).
CONCLUSIONS:
The Norwood procedure with RV-PA promotes better and more balanced pulmonary artery growth with significantly greater Left PA size when compared to the Norwood with mBTS. The RV-PA may also improve early operative mortality. However, lower arterial oxygen saturations and RV-PA conduit stenosis increase the need for an additional shunt during the first inter-stage or earlier timing of Glenn surgery.   
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