Background <p>Isolated congenital supravalvular pulmonary stenosis is an exceedingly rare cardiac anomaly, typically characterized by a discrete membrane above the valve obstructing the main pulmonary artery. We present a previously unreported anatomical variation in which this membrane fused with one of the pulmonary valve leaflets, forming a distinct pouch-like configuration.</p> Case presentation <p>A 44-year-old male presented with progressive exertional dyspnea. Preoperative echocardiography identified severe pulmonary stenosis and an obstructing supravalvular membrane, with a peak transvalvular gradient of 170 mmHg. Intraoperative exploration revealed that the pulmonary valve is trileaflet, with visibly thickened and fused commissures, causing severe pulmonary valve stenosis. Uniquely, the supravalvular pulmonary membrane fused with one leaflet forming a pouch-like configuration. Surgical separation of the fused commissures was performed, which successfully relieved the obstruction. The patient recovered well and reported complete symptom resolution at one-month follow-up.</p> Conclusion <p>This case presents a unique anatomical variant of isolated congenital supravalvular pulmonary stenosis, characterized by fusion between the abnormal supravalvular membrane and one valve leaflet. The surgical approach adopted achieved acceptable results and substantially improved the patient’s clinical condition.</p>