1.    Congenital anomalies of extraparenchymal pulmonary venous developmental

       a.    Absence of normal pulmonary venous connections with the heart

       b.    Stenosis or occlusion of normal pulmonary venous connections at, or before, birth

       c.    Stenosis or occlusion of anomalous pulmonary venous connections before surgical repair

       d.   Stenosis or occlusion of pulmonary veins associated with cor triatriatum sinister

2.   Postnatal obstruction of the extraparenchymal pulmonary veins

       a.    Stenosis or occlusion of normal pulmonary venous connections associated with

              •    Premature birth and chronic lung disease

              •.   Congenital heart defects

              •.   Chromosomal variants

              •.   Infectious or inflammatory diseases of the lung, mediastinum, or pericardium

              •.   Other inflammatory processes (necrotizing enterocolitis)

              •.   Extrinsic compression of one or more pulmonary veins

       b.    Stenosis or occlusion of normal pulmonary venous connections after a surgical intervention, catheter-

               based intervention or catheter-mediated injury

              •.   Intra-atrial surgical baffles for systemic and pulmonary venous drainage

              •.   Heart or lung transplantation

              •.   Surgical or catheter-based interventions to manage atrial dysrhythmias

              •.   Trauma of one or more pulmonary veins

       c.    Stenosis or occlusion of anomalous pulmonary veins after surgical correction

              •    Focal stenosis of the anastomosis between corrected anomalous pulmonary vein(s) and the left

                    atrium

              •.   Intraluminal stenosis of pulmonary veins with, or without, an adequate surgical anastomosis of

                    anomalous pulmonary veins

3.   Postnatal obstruction originating in the venules of the lung parenchyma

      a.    Pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis