There are usually two superior and two inferior main pulmonary veins, the former draining the middle and upper lobes on the right side and the upper lobe on the left with the inferior veins draining the lower lobes (Fig. 11.1). The pulmonary veins drain the oxygenated pulmonary blood to the left atrium. Computerized tomography is now used as an excellent way to image these structures (Fig. 11.2). As with many venous structures, there are occasional variations in this pattern. On the right side the most common variation is to have three separate pulmonary veins with the third vein usually draining the right middle lobe. On the left side the most common variation is a single common trunk that all the veins empty into before reaching the left atrium (Fig. 11.3). Less commonly more complex arrangements may be seen (Fig. 11.4). These patterns are usually referred to as normal variants, since the blood still follows the same pathway.

In anomalous pulmonary venous drainage, the veins drain into a different structure, usually directly to the superior vena cava or to the right atrium. This will be discussed in more detail in subsequent text.