This MRI is a coronal view of the LA, MV and LV in RAO position . Courtesy Ashley Davidoff MD.  The CommonVein.com 32111

Pulmonary Arteries and Pulmonary Veins Ashley Davidoff TheCommonVein.com 79754b04b09b

Pulmonary Arteries and Pulmonary Veins Ashley Davidoff MD TheCommonVein.com  31592-1

 

This diagram shows two secondary lobules with a central bronchovascular bundle and peripheral venular system. The lymphatics that travel with the pulmonary veins are not shown. Courtesy of Ashley Davidoff M.D. 32189

Venous Drainage of the Lungs
Category Details Applied Anatomy (Imaging Findings)
Etymology
  • Vein: From Latin vena.
  • Pulmonary: Pulmo (Lung).
  • Concept: Pulmonary veins are unique in the adult body because they carry oxygenated (red) blood, unlike systemic veins.
Definition
  • The vascular system responsible for returning blood from the lungs to the Left Atrium.
  • Dual Drainage:1. Pulmonary Veins: Drain the respiratory zone (Oxygenated).

    2. Bronchial Veins: Drain the large airways (Deoxygenated).
  • Total Return: The 4 pulmonary veins carry the entire cardiac output (~5 L/min) into the Left Atrium.
Anatomy: Pulmonary Veins
  • Number: Typically 4 veins (Right Superior, Right Inferior, Left Superior, Left Inferior).
  • Course: Run within the interlobular septa (periphery of lobules), separate from the arteries/bronchi.
  • Anatomic Distinction: Arteries and Bronchi run together in the center of the lobule. Veins run alone at the edge. This helps distinguish structures on CT.
Anatomy: Bronchial Veins
  • Superficial System: Drains large bronchi into the Azygos/Hemiazygos system (Right Atrium).
  • Deep System: Drains small airways directly into the Pulmonary Veins (Left Atrium).
  • Physiological Shunt: The deep bronchial veins dump deoxygenated blood into the oxygenated pulmonary veins. This is why arterial oxygen saturation (SaO2) is normally 98-99% rather than 100%.
Parts (The 4 Veins)
  • Right Superior (RSPV): Drains RUL + RML.
  • Right Inferior (RIPV): Drains RLL.
  • Left Superior (LSPV): Drains LUL + Lingula.
  • Left Inferior (LIPV): Drains LLL.
  • Common Ostium: In ~25% of people, the two left veins fuse before entering the heart, forming a single “Left Common Pulmonary Vein.” Important to know before Atrial Fibrillation ablation procedures.
Size
  • Diameter: Variable, distensible.
  • Upper vs Lower: In an upright person, lower lobe veins are larger due to gravity.
  • Cephalization: In early Heart Failure (PCWP 12-18 mmHg), upper lobe veins dilate to become equal in size to lower lobe veins (Redistribution).
Position
  • Hilar Relations:Right: Veins are anterior and inferior to the PA/Bronchus.

    Left: Veins are anterior and inferior.
  • “Antler Sign”: On a frontal Chest X-ray, the upper lobe pulmonary veins branching upwards from the hilum look like antlers. In pulmonary venous hypertension, these “antlers” become prominent.
Character
  • Thin-walled: Much thinner than arteries; prone to compression.
  • Valveless: Blood flows continuously down the pressure gradient.
  • No Valves: Because there are no valves, elevated Left Atrial pressure (Heart Failure/Mitral Stenosis) is transmitted instantly back to the lung capillaries, causing edema.
Time
  • Embryology: Develop from the merging of the primitive pulmonary vein (from the Left Atrium) and the pulmonary vascular plexus.
  • TAPVR: Total Anomalous Pulmonary Venous Return. The primitive vein fails to connect to the LA, and pulmonary veins drain into the SVC, IVC, or Coronary Sinus instead (Cyanotic heart disease).
Blood Supply (Vasa Vasorum)
  • Supplied by bronchial arteries.
  • N/A.
Lymphatic Drainage
  • Interlobular lymphatics run alongside the veins.
  • Kerley B Lines: When venous pressure rises (CHF), the lymphatics next to the veins swell. This thickens the interlobular septa, creating visible horizontal lines at the lung bases on X-ray.
Physiology & Pathophysiology
  • Pressure: Low (~8-12 mmHg).
  • Function: Reservoir for the Left Atrium.
  • Pulmonary Edema: When venous hydrostatic pressure exceeds oncotic pressure (~25 mmHg), fluid leaks out of the capillaries into the interstitium and alveoli.
Diseases
  • CHF: Most common cause of venous distension.
  • Stenosis: Post-ablation stenosis.
  • Veno-Occlusive Disease (PVOD): Rare blockage of small veins.
  • Scimitar Syndrome (PAPVR): An anomalous right pulmonary vein drains into the IVC, creating a curved shadow on CXR resembling a Turkish sword (Scimitar) along the right heart border.
Radiology
  • CXR: Horizontal vessels entering the LA.
  • CT: Veins run towards the LA; Arteries run into the lung.
  • Differentiation: Trace the vessel. If it goes to the Left Atrium, it’s a vein. If it comes from the Right Ventricle/Main PA, it’s an artery. Veins are usually horizontal; Arteries are vertical.
Key Points & Pearls
  • Oxygenated blood.
  • Valveless.
  • Run in Interlobular Septa (Periphery).
  • 4 Veins (usually).
  • Stag’s Antlers: Prominent upper lobe veins = Venous Hypertension.
  • Kerley Lines: Septal edema due to venous congestion.

The anatomical specimen shows an opened left atrium with each of the pulmonary veins entering and the left atrial   Ashley Davidoff MD TheCommonVein.com 06426c01.8s

Left Atrium from Posterior receiving Four  Pulmonary Veins
The specimen of heart and lungs is examined from posteriorly with the left atrium and 4 pulmonary veins. (overlaid in pearl white) The trachea and bronchi are intact (green). The left atrium lies just below in the angle of the carina. Courtesy Ashley Davidoff MD.  The CommonVein.com  08376c02.82s

Courtesy Ashley Davidoff MD.  The CommonVein.com  44659c02.800

Courtesy Ashley Davidoff MD.  The CommonVein.com 31662b3

Courtesy Ashley Davidoff MD.  The CommonVein.com 31236

Romance in the Lungs Courtesy Ashley Davidoff MD.  The CommonVein.com (lungs-0018catalogue-signed-small-3)

This MRI is a coronal view of the LA, MV and LV in RAO position . Courtesy Ashley Davidoff MD.  The CommonVein.com 32111

Courtesy Ashley Davidoff MD.  The CommonVein.com 39704

This reformatted image shows the classical branching pattern of the pulmonary veins with two upper and two lower lobe veins on either side. Courtesy Ashley Davidoff MD.  The CommonVein.com 37756b01


Courtesy Ashley Davidoff MD.  The CommonVein.com 42379.800

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