Variations of pulmonary vein drainage critical for lung resection assessed by three-dimensional computed tomography angiography

Background: It is important to understand pulmonary vein drainage pattern variations and their frequency in order to perform safe anatomical pulmonary resection. Methods: Variations and frequencies were assessed using three-dimensional computed tomography angiography (3D-CT) in 194 patients. In cases where the tumor or lymph node caused atelectasis or compression of hilar structures, the involved lobes were excluded from the analyses. Results: We confirmed variant drainage patterns in 15/189 (8.0%) patients in the right upper lobe (RUL), 29/189 (15.3%) in the right middle lobe (RML), 18/192 (9.5%) in the right lower lobe (RLL), and 5/187 (2.6%) in the left upper lobe (LUL). There was no variant type in the left lower lobe (LLL). There were 14 (7.4%) cases of anomalous superior posterior pulmonary vein of RUL (V²) drainage: V2 draining to the superior pulmonary vein (SPV) (n = 2, 1.1%), V2 to the inferior pulmonary vein (IPV) (n = 7, 3.7%), V2 to the left atrium (LA) (n = 2, 1.1%), and V⁶ to the apical pulmonary vein of the RLL (n = 3, 1.6%). There was a posterior pulmonary vein, V³ to RML pulmonary vein in one case (0.5%). The RML pulmonary vein drained into the IPV in 14 (7.4%) and into the LA in 15 (7.9%) cases. The right V6 directly drained into the LA in 15 (7.9%) and V⁶ into the SPV in 3 (1.6%) cases. The lingular pulmonary vein drained into the IPV in one case (0.5%) and into the LA in two cases (1.1%). The inferior lingular pulmonary vein V⁵ drained into the IPV and into the LA in one case (0.5%), respectively. Conclusion: We describe anomalous pulmonary venous drainage patterns and their frequencies particular to anatomic surgical resection. 3D-CT is useful to find such variations.