Bilateral Pulmonary Artery Mobilization Enhances Vascular Growth in Systemic-to-Pulmonary Shunt Surgery

To evaluate whether complete hilum-to-hilum bilateral pulmonary artery (PA) mobilization at the time of systemic-to-pulmonary artery shunt (APS) is associated with greater two-year PA growth than conventional APS without mobilization in cyanotic congenital heart disease (CCHD), particularly in patients receiving 3.5-4.0-mm conduits. We retrospectively analyzed 245 consecutive infants who underwent APS between January 2018 and September 2025. Patients were stratified by technique: Group A (n = 128) received complete bilateral PA mobilization with a 3.5- or 4.0-mm shunt; Group B (n  = 117) underwent standard APS without mobilization. The primary endpoint was change in McGoon index (sum of branch PA diameters normalized to the diameter of the descending aorta at the diaphragm) from baseline to 24 months, assessed by transthoracic echocardiography, CT angiography, or cardiac MRI. Secondary endpoints included shunt patency and hospital length of stay (LOS). Baseline characteristics were similar (age 1.4 ± 0.7 vs. 1.4 ± 0.6 years; weight 6.1 ± 1.8 vs. 6.2 ± 1.8 kg; all p > 0.05). Group A showed a greater increase in McGoon index (1.26 ± 0.11 to 1.62 ± 0.14; p < 0.001) than Group B (1.22 ± 0.09 to 1.42 ± 0.12; p < 0.001), with a significant between-group difference at 24 months (p < 0.001; Cohen's d = 1.49). ΔMcGoon correlated inversely with LOS (ρ=-0.844; p < 0.001). Shunt patency was higher with mobilization (96.1% vs. 88.9%; p  = 0.03). In this two-year cohort, complete bilateral PA mobilization during APS was associated with greater PA growth, higher shunt patency, and a shorter hospital stay in the mobilization group, although the era-based design precludes definitive causal inference. These findings support incorporation of hilum-to-hilum mobilization as a standardized, modifiable operative step, while prospective, adjusted analyses are needed to confirm durability and subgroup effects.