Early and late results and the effects on pulmonary arteries of balloon dilatation of the right ventricular outflow tract in tetralogy of Fallot.

BACKGROUND Balloon dilatation of the pulmonary valve remains controversial as a palliative procedure in tetralogy of Fallot. AIMS To determine the clinical outcome, growth of the pulmonary vascular tree and findings at surgery of balloon dilatation of the pulmonary valve performed as a palliation in infants with tetralogy of Fallot. METHODS AND RESULTS Thirty-three severely cyanosed infants (mean age of 3 months for the whole population, including seven neonates) underwent this procedure from June 1990 to January 1997. After balloon dilatation, systemic oxygen saturation increased from a mean value of 76 +/- 9% to 88 +/- 7% (P < 0.001). The procedure was accomplished without complications. Four patients had recurrent hypoxic spells after dilatation leading to surgical repair within 30 days of dilatation (three modified Blalock-Taussig shunts and one complete repair). A control study was performed at a mean of 6.1 +/- 4.5 months after dilatation in 16 patients to establish growth of the pulmonary vascular tree (repeat catheterization in nine patients and surgical pulmonary annulus calibration in seven). The pulmonary annulus increased from a mean Z score of -4.1 +/- 0.9 SD to -2.5 +/- 1.1 SD (P < 0.001). Z score for the right pulmonary artery from -3.0 +/- 0.6 SD to -1.9 +/- 1.2 SD (P = 0.007) and the Z score for the left pulmonary artery from -2.7 +/- 0.7 SD to -1.6 +/- 1.3 SD (P = 0.021). At late follow-up (mean of 9 months after dilatation, range 3 to 54 months), 28 patients underwent complete repair. Trans-annular patching was required in 43% of patients. Four post-operative deaths were observed, none dilatation related. CONCLUSION Balloon dilatation of the pulmonary valve is an effective and safe palliation in tetralogy of Fallot. It promotes growth of the pulmonary vascular tree, reducing the need for trans-annular patching and is recommended in symptomatic infants of very young age, with a small pulmonary annulus (Z value below -4 SD) and associated cardiac anomaly.