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

Abstract

Background: The main difference between extreme tetralogy of Fallot (TOF) and pulmonary atresia with ventricle septal defect (PA/VSD) is anterograde pulmonary blood flow (APBF). It is speculated that the association of modified Blalock-Taussig shunt (mBTS) with APBF favours shunt thrombosis, but promotes better pulmonary artery growth.

Aim: To compare pulmonary artery growth after mBTS between TOF and PA/VSD.

Methods: From 1995 to 2018, 77 mBTS procedures were performed in infants (aged<1 year): 45 for TOF; 32 for PA/VSD. Using a 1/1 propensity score-matched analysis, 38 patients were included (19 per group). Delta Nakata was defined as the difference in the Nakata index before biventricular repair and before mBTS.

Results: After matching, the preoperative Nakata index was similar in the two groups (TOF 101±34 vs. PA/VSD 106±35 mm²/m²; P=0.75). Age and weight were similar (TOF 24±20 days, 3.3±0.6kg vs. PA/VSD 24±33 days, 3.3±0.9kg; P=0.84 and P=0.77, respectively). There was no difference in rates of in-hospital mortality (TOF 0% vs. PA/VSD 10%; P=0.13) or mBTS thrombosis (TOF 15% vs. PA/VSD 10%; P=0.63). The left and right pulmonary artery diameters at time of biventricular repair were similar (TOF 7.5±2.2 and 6.7±2.1 vs. PA/VSD 8±2.7 and 7.1±2.5mm; P=0.43 and P=0.78, respectively), as were delta Nakata (TOF 112±102 vs. PA/VSD 107±66 mm²/m²; P=0.89), median age for biventricular repair (P=0.83) and reintervention rates (TOF 10% vs. PA/VSD 15%; P=0.67).

Conclusions: We found no difference in pulmonary artery growth between APBF with mBTS versus mBTS alone. Thus, we could not show an increase in mBTS thrombosis with APBF.

Keywords: Anastomose de Blalock–Taussing modifié; Atresie pulmonaire avec communication interventriculaire; Major aortopulmonary collaterals; Palliative surgery; Pulmonary atresia with ventricular septal defect; Tétralogies de Fallot.