Objects. We investigated the effects of the right ventricular outflow tract (RVOT) of Tetralogy of Fallot (ToF) on pulmonary valve (PV) growth following balloon valvuloplasty of the pulmonary valve (BPV). Background: In ToF patients, BPV promotes pulmonary artery and PV growth, though a transannular patch may be required.
Methods. Clinical and catheterization data from 26 infant patients who underwent preoperative BPV during the past 9 years were retrospectively studied. Results. The PV annulus grew significantly from -4.3 SD before BPV to -1.9 SD before ToF radical surgery, and then to -2.0S D in all patients except one. No significant increase in RVOT Z-score was accompanied by decreased RVOT size in 11 patients. There was no significant relationship between the RVOT at the time of BPV and PV annulus prior to total correction, between the RVOT and PV annulus prior to total correction, or between the RVOT diameter before BPV and increase in PV Z-score. In one patient, there was a significant relationship between increase in RVOT-Z score and increase in PV Z-score. In 3 patients complicated with a cyanotic spell, RVOT diameter rapidly decreased and the balloon size/PV annulus ratio (%) during BPV was less than 120%. Conclusion: PV annulus size just prior to ToF total repair is determined by PV annulus size at the first examination plus PV growth, which is dependent on RVOT growth after BPV. A balloon catheter greater than 120% of the PV annulus should be used during BPV to accelerate RVOT growth after the procedure.