A 29-year-old woman presented with a symptomatic large atrial septal defect, a small left ventricle with a modest left atrium, mild to moderate nonrheumatic mitral valve incompetence, an apex-forming very large right ventricle and suprasystemic pulmonary artery pressure. Following one year of preprocedural drug treatment to lower pulmonary hypertension, she underwent percutaneous closure of the atrial septal defect with a customized fenestrated device that enabled gradual adaptation to the occlusion of the interatrial communication. This special case demonstrates the benefits of using a fenestrated occluder device in patients with pulmonary hypertension and components of left ventricular diastolic dysfunction, which is considered to be high risk and not amenable to therapeutic intervention.