Variations in Draining Patterns of Right Pulmonary Veins at the Hilum and an Anatomical Classification

Pulmonary veins carry oxygenated blood from the lungs to the left atrium. Variations are quite common in the pattern of drainage. The present study was undertaken to evaluate the incidence of different draining patterns of the right pulmonary veins at the hilum by dissecting the human fixed cadaveric lungs. Clinically, pulmonary veins have been demonstrated to often play an important role in generating atrial fibrillation. Hence, it is important to look into the anatomy of the veins during MR imaging and CT angiography. In 53.8% of cases, the right superior lobar vein and right middle lobar vein were found to be united together to form the right superior pulmonary vein. In contrast to this, in 11.53% of cases, right middle lobar vein united with the right inferior lobar vein to form the right inferior pulmonary vein, while in 26.9% of cases, the right superior lobar vein, right middle lobar vein, and right inferior lobar vein drained separately. 1. Introduction Pulmonary veins drain oxygenated blood from the lungs to the left atrium of the heart. The lobular tributaries lie mainly in the interlobular septa. One main vein drains each bronchopulmonary segment usually on the anterior surface of the corresponding bronchus. Veins also run between the segments and on the mediastinal and fissural surfaces of the lungs; some veins cross the line of fissure when the fissures are incomplete. The veins of the right medial segment of inferior lobe frequently arise from the veins of the middle lobe. The superior right pulmonary vein drains the right superior and middle lobe and thus corresponds to the superior left pulmonary vein which drains the left superior lobe. The right inferior pulmonary vein and left inferior pulmonary veins drain the corresponding inferior lobes [1]. The present study is to ascertain the incidence of different draining patterns of the right pulmonary vein at the hilum as it is clinically very important to look into the anatomy of the veins during MR imaging and CT angiography. 2. Material and Methods The study involved twenty-six formalin-fixed adult cadaveric lungs of unknown sex from Bangalore Medical College & Research Institute, Bangalore, Karnataka. The dissection initially involved identifying the structures at the hilum. The pulmonary veins were picked up and their tributaries were traced peripherally by meticulously dissecting the lung tissue using blunt forceps. Interestingly different patterns in the drainage of pulmonary veins were noted. 3. Results The different draining patterns noted are as follows. In 53.8% of dissected lungs