Patients with isolated PS who have previously undergone an intervention on the pulmonary valve require ongoing clinical follow-up and mon- itoring of PR, RV size and function, and functional capacity. This may include echocardiography, CPET, and advanced imaging. The right ventricle in patients with PR after intervention for PS may be smaller than in patients with TOF; however, patients with PR may have evidence of decreased RV ejection fraction or decreased exercise ca- pacity. Pulmonary valve replacement can improve symptoms for patients with symptoms that are attributable to moderate or greater PR, and can improve RV size and/or RV function if there is RV dilation or decreased RV ejection fraction. 2. PR resulting from treatment of isolated PS may have progressive impact on RV size and function, and may result in symptoms, such that pulmonary valve replacement would be considered. Serial follow-up for clinical evaluation, CPET, and imaging to eval- uate for symptoms, exercise intolerance attribut- able to PR, and/or RV dilation or RV dysfunction will allow appropriate timing of intervention if needed. 3. There are no data to suggest appropriate timing for pulmonary valve replacement in the presence of RV dilation, but it is likely inappropriate to di- rectly extrapolate the data applicable to patients However, RV dilation or dysfunc- tion should improve, or at least not progress fur- ther, if the volume overload from PR is alleviated by pulmonary valve replacement. Thus, although specific RV size criteria are not available for these patients to determine timing of pulmonary valve replacement, patients with progressively worsen- ing RV size or function presumably represent a subset of patients for whom valve replacement could be beneficial. 4.3.2. Branch and Peripheral Pulmonary Stenosis Recommendations for Branch and Peripheral PS Referenced studies that support recommendations are summarized in Online Data Supplement 40. 