Pulmonary Veins: The Only Veins Carrying Oxygenated Blood

The pulmonary veins are unique: they are the only veins in the adult body that carry oxygenated blood. There are typically four—two from each lung—draining into the left atrium.

Anatomy

• Right superior pulmonary vein (RSPV)
• Right inferior pulmonary vein (RIPV)
• Left superior pulmonary vein (LSPV)
• Left inferior pulmonary vein (LIPV)

Variations are common (e.g., common trunk, accessory veins). They run anterior to the pulmonary arteries at the hilum.

Function

After gas exchange in pulmonary capillaries, oxygenated blood enters the pulmonary veins → left atrium → left ventricle → systemic circulation.

Clinical Significance

• Atrial fibrillation ablation: Pulmonary vein isolation (PVI) targets ectopic foci in PV sleeves (especially LSPV, RSPV).
• Pulmonary vein stenosis: Congenital or post-ablation; causes pulmonary hypertension.
• Imaging: CT/MRI for AF planning; TEE for intraprocedural guidance.
• Total anomalous pulmonary venous connection (TAPVC): Congenital defect; veins drain into systemic venous system → cyanosis.

Key Distinction

All other veins carry deoxygenated blood; pulmonary arteries carry deoxygenated blood. The pulmonary veins are the exception that proves the "arteries carry oxygenated blood" rule wrong.