Pulmonary arterial hypertension caused by compression of the left lower pulmonary vein in children

To investigate, through four clinical cases, whether compression-induced deformation of the left lower pulmonary vein by the descending aorta is an etiological factor in certain cases of severe pulmonary arterial hypertension (PAH) in children. Four pediatric patients with severe PAH and left lower pulmonary vein stenosis (PVS) due to external compression by the descending aorta underwent surgical repair under general anesthesia with hypothermic extracorporeal circulation. The first patient underwent patch augmentation of the left lower pulmonary vein using pericardium. The remaining three patients underwent left lower pulmonary vein reimplantation to relieve the compression. Preoperatively, following oxygen inhalation, the total pulmonary resistance indexed to body surface area in the first three patients was 11.7, 12.6, and 20.2 Wood units × m², respectively. Intraoperative observation confirmed normally developed left lower pulmonary veins with smooth intima and no intrinsic stenosis. Postoperatively, pulmonary artery pressure normalized in all cases. Computed tomography confirmed complete relief of the venous compression. Postoperative right heart catheterization in the first three patients showed indexed total pulmonary resistances of 8.6, 9.1, and 13.9 Wood units × m². All four patients exhibited significant symptomatic improvement. In children with severe PAH of unexplained origin, impaired drainage of the left lower pulmonary vein secondary to compression by the descending aorta may be an initiating pathogenic factor. Surgical correction of this compression represents a novel therapeutic strategy for a subset of patients with idiopathic PAH.