BACKGROUND: This study assesses the results of early insertion of a pulmonary valve for chronic pulmonary regurgitation based on right ventricular volume measurements. METHODS: Valved conduits were prospectively inserted in 39 patients (aged 14 to 39 years) when the right ventricular (RV) end-diastolic volume index on magnetic resonance imaging (MRI) exceeded 150 mL/m2. Changes in morphology and function of the RV were prospectively analyzed by an MRI at 6 months postoperatively (available in 21 patients). RESULTS: There were no early or late deaths. All conduits showed good function at a median 15 month follow-up. Postoperative RV end-systolic and end-diastolic volumes showed a significant positive correlation (p = 0.005 and p < 0.0001), while postoperative left ventricular (LV) ejection fraction showed a significant negative correlation (p = 0.03) with preoperative RV end-diastolic volume index. Seven patients who achieved normal RV end-diastolic volume index (< or = 100 mL/m2) (group 1) when compared with 14 remaining patients (group 2) showed that they differed significantly with respect to their preoperative RV end-diastolic volume index (170.3 +/- 21.1 vs 203.6 +/- 35.6; p = 0.02) and postoperative LV ejection fraction (59.9 +/- 4.2 vs 54 +/- 7%, p = 0.03). CONCLUSIONS: Our results show that the improvement in ventricular dimensions and functions directly correlates with the timing of pulmonary valve insertion. Early insertion leads to normalization and late insertion leads only to improvement. These observations, along with a low morbidity for these reoperations, justify earlier reintervention in cases of chronic pulmonary regurgitation. A RV end-diastolic volume index of 150 mL/m2 seems to be a practical cutoff value to prescribe pulmonary valve insertion.