Does initial shunt type for the Norwood procedure affect echocardiographic measures of cardiac size and function during infancy?: the Single Vventricle Reconstruction trial.

BACKGROUND: The Pediatric Heart Network trial comparing outcomes in 549 infants with single right ventricle undergoing a Norwood procedure randomized to modified Blalock-Taussig shunt or right ventricle-pulmonary artery shunt (RVPAS) found better 1-year transplant-free survival in those who received RVPAS. We sought to compare the impact of shunt type on echocardiographic indices of cardiac size and function up to 14 months of age. METHODS AND RESULTS: A core laboratory measured indices of cardiac size and function from protocol exams: early after Norwood procedure (age 22.5 ± 13.4 days), before stage II procedure (age 4.8 ± 1.8 months), and at 14 months (age 14.3 ± 1.2 months). Mean right ventricular ejection fraction was <50% at all intervals for both groups and was higher in the RVPAS group after Norwood procedure (49 ± 7% versus 44 ± 8%; P<0.001) but was similar by 14 months. Tricuspid and neoaortic regurgitation, diastolic function, and pulmonary artery and arch dimensions were similar in the 2 groups at all intervals. Neoaortic annulus area (4.2 ± 1.2 versus 4.9 ± 1.2 cm(2)/m(2)), systolic ejection times (214.0 ± 29.4 versus 231.3 ± 28.6 ms), neoaortic flow (6.2 ± 2.4 versus 9.4 ± 3.4 L/min per square meter), and peak arch velocity (1.9 ± 0.7 versus 2.2 ± 0.7 m/s) were lower at both interstage examinations in the RVPAS compared with the modified Blalock-Taussig shunt group (P<0.001 for all), but all were similar at 14 months. CONCLUSIONS: Indices of cardiac size and function after the Norwood procedure are similar for modified Blalock-Taussig shunt and RVPAS by 14 months of age. Interstage differences between shunt types can likely be explained by the physiology created when the shunts are in place rather than by intrinsic differences in cardiac function. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00115934.

Doppler flow patterns in the right ventricle-to-pulmonary artery shunt and neo-aorta in infants with single right ventricle anomalies: impact on outcome after initial staged palliations.

BACKGROUND: A Pediatric Heart Network trial compared outcomes in infants with single right ventricle anomalies undergoing Norwood procedures randomized to modified Blalock-Taussig shunt (MBTS) or right ventricle-to-pulmonary artery shunt (RVPAS). Doppler patterns in the neo-aorta and RVPAS may characterize physiologic changes after staged palliations that affect outcomes and right ventricular (RV) function. METHODS: Neo-aortic cardiac index (CI), retrograde fraction (RF) in the descending aorta and RVPAS conduit, RVPAS/neo-aortic systolic ejection time ratio, and systolic/diastolic (S/D) ratio were measured early after Norwood, before stage II palliation, and at 14 months. These parameters were compared with transplantation-free survival, length of hospital stay, and RV functional indices. RESULTS: In 529 subjects (mean follow-up period, 3.0 ± 2.1 years), neo-aortic CI and descending aortic RF were significantly higher in the MBTS cohort after Norwood. The RVPAS RF averaged <25% at both interstage intervals. Higher pre-stage II descending aortic RF was correlated with lower RV ejection fraction (R = -0.24; P = .032) at 14 months for the MBTS cohort. Higher post-Norwood CI (5.6 vs 4.4 L/min/m(2), P = .04) and lower S/D ratio (1.40 vs 1.68, P = .01) were correlated with better interstage transplantation-free survival for the RVPAS cohort. No other Doppler flow patterns were correlated with outcomes. CONCLUSIONS: After the Norwood procedure, infants tolerated significant descending aortic RF (MBTS) and conduit RF (RVPAS), with little correlation with clinical outcomes or RV function. Neo-aortic CI, ejection time, and S/D ratios also had limited correlations with outcomes or RV function, but higher post-Norwood neo-aortic CI and lower S/D ratio were correlated with better interstage survival in those with RVPAS.