Pulmonary veins

The pulmonary veins drain oxygenated blood from the lungs to the left atrium. A small amount of blood is also drained from the lungs by the bronchial veins

Gross anatomy

There are typically four pulmonary veins, two draining each lung:

• right superior: drains the right upper and middle lobes
• right inferior: drains the right lower lobe
• left superior: drains the left upper lobe
• left inferior: drains the left lower lobe

The pulmonary veins course in the intersegmental septa and as such do not run with the bronchi like the pulmonary arteries do.

The superior pulmonary veins take an oblique inferomedial course whereas the inferior pulmonary veins run horizontally peripherally before taking a more vertical course. They pass through the lung hilum, antero-inferiorly to the pulmonary arteries, forming a short intrapericardial segment, to drain into the left atrium. The ostia of the inferior pulmonary veins are more posteromedial and the left pulmonary veins being more superior. 

There is extensive communication with deep bronchial veins within the lung and with the superficial bronchial veins at the hilum.

The pulmonary veins are covered by a short (~9 mm) myocardial layer, which is often the electrical focus of atrial fibrillation with the left superior pulmonary vein being the foci for almost half of cases. These abnormal foci can be treated with RFA.

Variant anatomy

Typical anatomy described above is found in ~70% of patients ^1-4. Variant configurations are more common on the right and include:

• common trunks
  • common draining trunk of left superior and inferior pulmonary veins
• accessory (additional pulmonary veins)
  • single accessory right middle pulmonary vein (~10%)
  • two accessory right middle pulmonary veins
  • one accessory right middle pulmonary vein and one accessory right upper pulmonary vein 
  • superior segment right lower lobe vein 
  • basilar segment right lower lobe vein
  • right top pulmonary vein (drains mostly posterior segment of right upper lobe and subsegmental areas of the superior segment of right lower lobe ⁶) 

There may also be partial anomalous pulmonary venous return (PAPVR) where the pulmonary veins drain into a structure besides the left atrium and rarely total anomalous pulmonary venous return (TAPVR) occurs where there is no drainage of pulmonary veins into the left atrium. 

Related pathology

• pulmonary venous varix
• upper lobe pulmonary venous diversion
• pulmonary arteriovenous malformation
• pulmonary vein thrombosis
• Scimitar syndrome
• pulmonary veno-occlusive disease
• pulmonary vein atresia
• pulmonary vein stenosis
• pulmonary venous obstructive syndrome