Differential branch pulmonary artery growth after the Norwood procedure with right ventricle–pulmonary artery conduit versus modified Blalock–Taussig shunt in hypoplastic left heart syndrome

Abstract

The Norwood procedure with right ventricle-pulmonary artery conduit is thought to improve postoperative hemodynamics in hypoplastic left heart syndrome, but its effects on pulmonary artery growth are unknown. This study evaluated pulmonary artery growth after the Norwood procedure in patients with a right ventricle-pulmonary artery conduit as compared with patients with a modified Blalock-Taussig shunt. A total of 159 patients at our institution underwent the Norwood procedure between January 2000 and September 2005. Patients were divided into group A or B if they had a modified Blalock-Taussig shunt (n = 103) or a right ventricle-pulmonary artery conduit (n = 56). Angiograms from the pre-Glenn catheterizations were used to measure pulmonary artery size and assess shunt stenosis (n = 64). Fifty-five (53.4%) patients in group A versus 40 (71.4%) in group B underwent Glenn surgery. Group B patients often required an additional shunt (modified Blalock-Taussig) before the Glenn procedure because of hypoxemia (8/40 vs 1/55; P = .004). Branch pulmonary artery growth was better in group B patients who did not require an additional shunt (Nakata index 212 vs 169 mm(2)/m(2); P = .004) and more balanced than in group A (right pulmonary artery/left pulmonary artery ratio = 1.02 vs 1.39; P = .001) as a result of greater left pulmonary artery size (29 vs 19 mm(2); P = .001). However, group B experienced more shunt stenosis (8/32 vs 2/32; P = .001), underwent the Glenn operation earlier (192 vs 246 days; P = .03), and had central pulmonary artery hypoplasia develop more often than group A patients (25/32 vs 14/32; P = .01). The Norwood procedure with a right ventricle-pulmonary artery conduit promotes better distal left pulmonary artery growth resulting in more balanced branch pulmonary artery size, but central pulmonary artery hypoplasia occurs more often. Early right ventricle-pulmonary artery conduit stenosis also increases the need for additional shunting or early Glenn surgery.