Mortality and Survival after Norwood Procedure Comparison between Shunt Type in Patients with Hypoplastic Left Heart Syndrome or Its Variants: A Systematic Review and Meta-Analysis Study

Background. In the Norwood procedure, a conduit is performed either from the subclavian artery to the pulmonary artery, Blalock–Taussig shunt (mBTs), or from the right ventricle to the pulmonary artery (RV-PA shunt). There are some concerns regarding the two shunts and which one is better according to morbidity and mortality in patients with hypoplastic left heart syndrome or its variants. Methods. We systematically searched PubMed, Web of Science, Scopus, Embase, and Cochrane Library databases from inception to 04/June/2021 to collect articles reporting a comparison of RV-PA shunt and mBTs. Results. Our meta-analysis showed that the mortality rate after 6 months, 1, 2, 3, 4, 5, and 6 years for the mBTS group was 16.3%, 28.6%, 34.8%, 42.4%, 44.6%, 45.1%, and 39.6%, respectively, and for the RV-PAS, 14.8%, 26.6%, 31%, 40.1%, 36.1%, 37.5%, and 34.0%, respectively. The mortality rate was significantly higher in the mBTs group at 1 and 2 years; otherwise, there is no significance differences. Overall complications rate was higher in the mBTs group than in the RV-PAs group (17.8% vs. 8.5%). In contrast, the rate of cardiac complications was higher in the RV-PAS group. Conclusions. The RV-PA shunt had lower mortality and overall complications rate than mBT shunt at the short-term outcome within the first two years, but at the long term, there was no difference between the two shunts. On the other hand, the mBT shunt had a lower incidence of cardiac complications at the early stage after the operations. However, some studies are poor due to the difficulties in conducting original research in this field. Therefore, we recommend conducting systematic reviews and original studies to compare these and other therapeutic procedures for these patients.