The outcome of stent implantation and redilatation was investigated in 4 pediatric patients with 7 stenotic lesions of the pulmonary vein (PV), paying particular attention to late neointimal proliferation. The minimal diameter of the lesions increased from 0.8-3.6 (2.3+/-1.1) mm to 3.6-8.4 (5.1+/-1.6) mm immediately after stent implantation. Although the pressure gradient across the lesion was not measured in patient 4, in patients 1-3, it decreased from 4-34 (18+/-13) mmHg to 3-15 (7+/-4) mmHg. Except for case 4, who achieved a lesion diameter of 8.4 mm after initial stent dilatation, the other 6 lesions all restenosed within a few months, with an increasing pressure gradient. One patient with multiple PV stenoses associated with persistent severe pulmonary hypertension died suddenly. However, repeat dilatations were effective in all other lesions. Furthermore, in one lesion in patient 1, no serious restenosis developed for 20 months after the lesion was dilated up to 5.6 mm. Although further follow-up is mandatory, the final stent diameter within a vessel may determine long-term patency, and aggressive redilatation may be crucial for successful therapy of such a difficult disease.