Impact of pulmonary artery coarctation on pulmonary artery growth and definitive repair following modified Blalock–Taussig shunt

Objective: Pulmonary artery coarctation may pose a risk for pulmonary stenosis and subsequent failure to achieve definitive repair. We sought to assess the impact of pulmonary artery coarctation on pulmonary artery growth. Methods: A retrospective chart review was performed in 130 patients, including 37 single ventricles with a modified Blalock–Taussig shunt as first palliation. Pulmonary artery coarctation was defined as discrete stenosis of the pulmonary artery, with a diameter of less than 3 mm and with the ductus arteriosus connected. Preoperative echocardiography showed pulmonary artery coarctation in 29 patients (22%). Concomitant pulmonary artery plasty was performed in 14 patients with discrete stenosis having a diameter of less than 2 mm. Results: Pre–modified Blalock–Taussig shunt left pulmonary artery z-scores were lower in patients with pulmonary artery coarctation than in those without (−4.0 [−5.8, −2.1] vs −1.7 [−2.6, −0.8], P < .001), and this remained the same even after modified Blalock–Taussig shunt (−2.5 [−5.1, −0.5] vs −0.5 [−2.4, 0.8], P = .010). Concomitant pulmonary artery plasty did not result in catch-up growth of the left pulmonary artery (post–modified Blalock–Taussig shunt left pulmonary artery z-score in patients with pulmonary artery plasty: −3.0 (−6.5, −2.0) versus those without: −1.8 (−3.3, −0.3), P = .279). Definitive repair/Fontan completion was achieved in 111 patients (85%), and this was not affected by the presence of pulmonary artery coarctation. Conclusions: Pulmonary artery coarctation affected disproportionate pulmonary artery growth throughout the staged repair, but did not result in failure of definitive repair/Fontan completion. Pulmonary artery plasty during the neonatal period did not contribute to catch-up growth of the left pulmonary artery; therefore, surgical indications and timing should be carefully considered.