Expansion
Four veins, two from each lung, draining to the left atrium
Expansion
- Four pulmonary veins: superior and inferior on each side
- They drain into the posterior wall of the left atrium
- They carry oxygenated blood
- They lie anterior and inferior to the other structures at each hilum
Two clinical points follow. First, ectopic electrical foci within the muscular sleeves that extend from the left atrium into the pulmonary veins are the commonest trigger for atrial fibrillation - which is why catheter ablation targets pulmonary vein isolation.
Second, because the veins enter the posterior left atrium, which lies directly in front of the oesophagus, an atrio-oesophageal fistula is a rare but catastrophic complication of ablation.