Pulmonary veins

Last revised by Raymond Chieng on 16 Aug 2023

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.

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

The pulmonary veins course in the intersegmental septa and as such do not run with the bronchi like the pulmonary arteries do 7.

As the pulmonary veins are draining into the left atrium, the superior pulmonary veins are located anteroinferior to the right pulmonary arteries while the inferior pulmonary veins run horizontally when compared to the vertical course taken by pulmonary arteries 1,7. The ostia of the inferior pulmonary veins are more posteromedial than the superior pulmonary veins and the ostia of left pulmonary veins being more superior than right pulmonary veins 1.

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 isolated with radiofrequency ablation.

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 other than the left atrium and rarely total anomalous pulmonary venous return (TAPVR) occurs where there is no drainage of pulmonary veins into the left atrium. 

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