Individual Pulmonary Vein Atresia in Adults: Report of Two Cases

Pulmonary vein stenosis and atresia may occur in one or more vessels and may present as an isolated anomaly or be associated with other congenital cardiac anomalies (1-3). Pulmonary vein atresia can be divided into 3 categories according to the extent of pulmonary vein involvement: common, unilateral and individual pulmonary vein atresia. Common and unilateral pulmonary vein atresias have been reported in infants and children, but rarely occur in adults.

Individual pulmonary vein atresia is defined as atresia of the lobar or segmental pulmonary vein and involves less than the unilateral lung. Only a few cases of individual pulmonary vein atresia in infants and young children have been reported (2). Severe individual pulmonary vein stenosis was previously observed in a 28-year-old man in whom a markedly narrowed ostium of the inferior pulmonary vein near the left atrium and appeared as a thin string-like vestige structure on CT (4).

To the best of our knowledge, the CT and angiographic findings of individual pulmonary vein atresia without a vestige of the involved pulmonary vein have not been reported. In this article, we present the imaging findings of individual pulmonary vein atresia in two adults along with a review of the relevant literature.

Pulmonary vein atresia can be divided into 3 categories: common, unilateral, and individual pulmonary vein atresia. These categories are based on the extent of involvement and this depends on the stage in which the normal development of the pulmonary venous drainage is affected (5). Individual pulmonary vein atresia is defined as atresia of the lobar or segmental pulmonary vein which involves symptoms less significant than unilateral pulmonary vein atresia. Pulmonary vein atresia can also be divided into congenital and acquired atresia. Congenital pulmonary vein atresia appears to occur from defective incorporation of the common pulmonary trunks into the left atrium, which leads to the obstruction of some or all of its branches. In rare cases of unilateral and individual pulmonary vein atresia, the venous obstruction may be acquired secondary to veno-occlusive disease or mediastinitis (2, 5).

In common pulmonary vein atresia, the pulmonary veins do not connect to the left atrium. Instead, they join together into a venous confluence close to the posterior aspect of the left atrium and drain into the bronchial venous system or the esophageal vein. An obligatory right-to-left shunt is present at the atrial level. Atresia of the common pulmonary vein is a cyanotic condition. The prominent symptoms include marked cyanosis, tachypnea, and dyspnea.

Unilateral pulmonary vein atresia may occur on either side of the lung with no right- or left-side predominance. The most frequent presenting complaints for infant cases include recurrent infections in the hypoplastic lung and hemoptysis due to the systemic collateral supply to the affected lung (6, 7). Unilateral pulmonary vein atresia can be identified in isolation or it may be found in patients with more severe congenital heart malformations. The involved lung becomes progressively smaller, and even the contralateral lung may appear edematous, reflecting the maldistribution of blood flow. In most patients, unilateral pulmonary vein atresia is diagnosed during infancy and only a few adult cases have been reported (1, 6).

In this article, individual pulmonary vein atresia refers to complete obliteration of an individual pulmonary vein in isolation. In contrast to atresia of the individual pulmonary vein, individual pulmonary vein stenosis can be defined as narrowing of an individual pulmonary vein. When the severe stenotic process is aggravated, it may manifest as atresia of a pulmonary vein. However, in cases of individual pulmonary vein stenosis, opacification of the stenotic pulmonary vein can be obtained by selective right and left pulmonary angiography.

Only a few cases of individual pulmonary vein atresia in infants and young children have been reported. Cullen et al. (2) reported on two children with individual pulmonary vein atresia and they were without additional congenital heart disease (2, 3). Both patients presented with recurrent pulmonary infections or hemoptysis. The radiographic findings showed a hypoplastic pulmonary artery ipsilateral to the pulmonary vein atresia. Venous drainage from the affected lung occurred into the systemic venous system via the azygos vein and bronchial venous system. Individual pulmonary vein atresia is a very rare condition; especially in adults. One adult case of severe stenosis of an individual pulmonary vein was reported (8). The findings of the report indicated a markedly narrowed ostium of the inferior pulmonary vein near the left atrium, which appeared as a thin string-like vestige structure on CT. Angiography demonstrated a tortuous vessel ascending the cephalad during the delayed phase as a collateral pathway (4).

In our study, the first case was lobar pulmonary vein atresia of the right lower lobe, whereas the second case was segmental pulmonary vein atresia of the apical segment located in the right upper lobe. For the first case, the right inferior pulmonary vein was atretic in the venoatrial junction, and drained into the superior pulmonary vein through the collaterals. For the second case, the apical segmental pulmonary vein of the right upper lobe was interrupted and it drained into another segmental pulmonary vein of the right upper lobe through the collaterals. On both cases, the ipsilateral main pulmonary artery was not hypoplastic. Both patients didn't show any symptoms such as hemoptysis, recurrent infection, or cardiac problems, which contrasts with the cases of infants and young children reported upon by Cullen et al. (2). Compared with the case of severe pulmonary stenosis reported by Saida et al. (4), there was no vestige of the affected pulmonary vein in our first case.

In summary, individual pulmonary vein atresia rarely occurs in adults without specific symptoms. The CT findings in our cases indicate the absence or interruption of normal pulmonary venous structures, and the presence of abnormal vascular structures that represented collaterals which developed for the involved lung parenchyma. Individual pulmonary atresia was confirmed by angiography in which the interrupted pulmonary vein drained into other ipsilateral pulmonary veins through the collaterals.