Aim:To correlate anatomic and genetic features of paediatric patients with pulmonary atresia,ventricular septal defect(VSD) and multiple aortopulmonary collateral arteries with surgical outcome. Methods:44 consecutive patients aged 33±40 mo underwent either primary one-stage unifocalization (n =32)-or palliative right ventricular outflow tract reconstruction (n=12) followed by secondary unifocalization and repair (n =10)-based on preoperative morphometric and functional evaluation of pulmonary blood sources. Chromosome 22q11.2 microdeletion occurred in 41%of cases. Combined VSD closure during one-stage procedures was guided by an intraoperative pulmonary flow study. Complete repair was accomplished in 35 cases (83%,95%CI 72-95%). Variables examined included occurrence of confluent intrapericardial pulmonary arteries,central pulmonary arteries,confluent intraparenchymal pulmonary arteries,dominant collateral or pulmonary arteries,and chromosome 22q11.2 microdeletion. The sensitivity and specificity of the pulmonary flow study in predicting postoperative pulmonary haemodynamics were also tested. Results:Eight year actuarial survival and freedom from reoperation were 85%and 63%,respectively. Sensitivity and specificity of the pulmonary flow study were 94%and 100%,respectively. None of the anatomical variables examined was significantly related to the outcome of treatment. The only statistically relevant association was detected between survival and occurrence of 22q11.2 microdeletion (p < 0.003). Logistic analysis showed an increased likelihood of positive outcome in relation to first-(p< 0.02) or second-stage (p < 0.04) complete correction. Conclusion:Morphology of pulmonary blood supply has no major impact on surgical outcome. Pulmonary flow study is a highly specific and sensitive intraoperative test. Chromosome 22q11.2 microdeletion remains the only variable significantly affecting survival. Aim: To correlate anatomic and genetic features of pediatric patients with pulmonary atresia, ventricular septal defect (VSD) and multiple aortopulmonary collateral arteries with surgical outcome. Methods: 44 consecutive patients aged 33 ± 40 mo underwent either primary one-stage unifocalization (n = 32) -or palliative right ventricular outflow tract reconstruction (n = 12) followed by secondary unifocalization and repair (n = 10) -based on preoperative morphometric and functional evaluation of pulmonary blood sources. Chromosome 22q11.2 microdeletion occurred in 41% of cases . Combined VSD closure during one-stage procedures was guided by intraoperative pulmonary flow study. Complete repair was accomplished in 35 cases (83%, 95% CI 72-95%). Variables examined included occurrence of confluent intrapericardial pulmonary arteries, central pulmonary arteries, confluent intraparenchymal pulmonary arteries, dominant collateral or pulmonary arteries, and chromosome 22q11.2 microdeletion. The sensitivity an d specificity of the pulmonary flow study in predicting postoperative pulmonary haemodynamics were also tested. Results: Eight year actuarial survival and freedom from reoperation were 85% and 63%, respectively. Sensitivity and specificity of the pulmonary flow study were 94% and 100% respectively. None of the anatomical variables examined was significantly related to the outcome of treatment. The only statistically relevant association was detected between survival and occurrence of 22q11.2 microdeletion (p <0.003). Conclusion: Morphology of pulmonary blood supply has no major impact on surgical outcome. Pulmonary flow study is a highly specific and sensitive intraoperative test. Chromosome 22q11. 2 microdeletion remains the only variable significantly affecting survival.