Gross and histologic anatomy of total anomalous pulmonary venous connections.

Among 49 heart specimens with total anomalous pulmonary venous connection (TAPVC), obstruction to pulmonary venous flow was present in all 13 cases with TAPVC below the diaphragm and in 53% of 36 cases with TAPVC above the diaphragm. Obstruction was produced by extrinsic pressures on the vein, intrinsic narrowing of the vein, or both. The histology of the narrowed veins was extremely variable, ranging from atrophy of the vein wall to hypertrophy of intima, media-adventitia, or both. Balloon dilation of narrowed veins was performed in 3 cases, without clinical or anatomic evidence of success.