Anterograde blood flow associated with Blalock–Taussig shunts does not modify pulmonary artery growth compared with Blalock–Taussig shunt alone

Objective The difference between extreme Tetralogy of Fallot (T4F) and pulmonary atresia with ventricle septal defect (PA/VSD) is the anterograde pulmonary blood flow. It is speculated that the association of modified Blalock-Taussig shunt (mBTs) and additional pulmonary blood flow favours shunt thrombosis but promotes better pulmonary arterial (PA) growth. This study sought to compare (PA) growth after mBTs shunt between T4F and AP/VSD. Methods From 1995 to 2018, 79 mBTs were performed in infants ( Results After matching, the preoperative Nakata was similar (101 ± 8 mm2/m2 in T4F; 106 ± 8 in AP/VSD P = 0.75). The age and weight were similar (24,3 ± 5 days, 3.3 ± 0.5 kg in T4F; 24,15 ± 4, 3.3 ± 0.9 in AP/VSD P = 0.84 and P = 0.77 respectively). The mBTs size was similar (4.15 ± 0.5 mm in T4F; 4.3 ± 0.5 in PA/VSD P = 0.35) There was no difference in in-hospital mortality (n = 0, in T4F; n = 2,11% in AP/VSD, P = 0.14) and mBTs thrombosis (3,16% in T4F; 2,11% in AP/VSD, P = 0.18). The time to extubation tended to be longer in T4F (5 ± 1days vs. 2 ± 1 P = 0.06). The left and right PA diameter at time of biventricular repair were similar (7.5 ± 0.5 mm, 7 ± 0.2 in T4F; 8.1 ± 0.7 mm, 7 ± 1 in AP/VSD P = 0.43 and P = 0.78, Fig. 1 , Fig. 2 ) and the Nakata delta (112 ± 23 mm2/m2 in T4F; 110 ± 17 in AP/VSD P = 0.78). Median time to complete repair was the same in the PA/VSD (12.26 [3.9–25] months) compared with T4F (9.7 [6.2–41.1] months) P = 0.87. The interstage reintervention were similar (3,16% in T4F; 4,22% in AP/VSD, P = 0.9). Conclusions Anterograde blood flow with mBTs did not increase the risk of mBTs thrombosis. We couldn’t show benefit of anterograde blood flow with mBTS versus mBTS for pulmonary arteries growth. Anterograde blood flow did increase the time to extubation, probably by increasing total pulmonary blood flow.