Changes in pulmonary artery size during and after staged extracardiac total cavopulmonary connection

Optimal development of the pulmonary arteries (PAs) is crucial for Fontan circulation. This study investigated longitudinal changes in PA size in patients who underwent staged Fontan palliation and analyzed their impact on outcomes.

Serial PA angiograms at bidirectional cavopulmonary shunt (BCPS), extracardiac total cavopulmonary connection (TCPC), and after TCPC were reviewed. PA index (PAI), right and left PAI, and PA symmetry index were calculated, and serial changes were compared.

Among 391 patients, right BCPS was performed in 328 (83.9%). The median age at TCPC was 2.1 years (interquartile range: 1.7-2.6 years). The most frequent diagnosis was hypoplastic left heart syndrome, in 148 patients (37.9%). PAI did not change between BCPS and TCPC (P = .564) or between pre-TCPC and post-TCPC (P = .569); however, right PAI increased between BCPS and TCPC (P = .007), while left PAI decreased (P < .001). Neither right PAI (P = .341) nor left PAI (P = .413) changed significantly between pre-TCPC and post-TCPC. The PA symmetry index decreased between BCPS and TCPC (P < .001) but remained stable thereafter (P = .912). Pre-TCPC small PAI predicted prolonged pleural effusion (P = .009; odds ratio [OR], 0.995) and ascites (P = .005; OR, 0.990). Pre-TCPC low symmetry index was a risk factor for mortality (P = .032; hazard ratio, 12.930), and its cutoff of 0.61 discriminated transplantation-free survival (P = .006).

During the staged Fontan procedure, the left PAI decreased, whereas the PAI and right PAI remained stable or increased. A PA symmetry index <0.61 predicts mortality following TCPC. This progressive asymmetry in left-to-right PA size affects in-hospital morbidity and emphasizes the importance of achieving balanced PA growth prior to Fontan completion.