With Anne Geoffray

Definition and Classification

• Stenosis represents narrowing of the pulmonary veins of varying degree, usually involving multiple veins unilaterally or bilaterally. It can be tubular, with extension into the lung, or discrete, tending to form at the junction of the veins with the left atrium.
• Atresia is a complete occlusion of the pulmonary veins that requires a coexisting anomalous pathway through intraparenchymal pulmonary or pulmonary-to-systemic venous anastomoses. It should be differentiated from pulmonary veno-occlusive disease (PVOD) in which obstructive intimal fibrosis involves the pulmonary venules and small veins, causing pulmonary hypertension.

Pathophysiology

• Congenital obstruction of the pulmonary veins without anomalous drainage can cause long-standing pulmonary venous hypertension.
• Over time, the pulmonary veins become markedly thickened, often resulting in obliteration of the lumina, leading to increased pulmonary capillary pressures and ultimately pulmonary arterial hypertension.
• Unilateral pulmonary vein obstruction may decompress through venous connections to the contralateral normal lung as well as to pulmonary-to-systemic venous collaterals and lymphatics.
• Pulmonary arterial blood flow is redistributed to the unaffected parts of the lungs.

Clinical Manifestation