What are the inferior vessels of the heart?

Inferior Vessels of the Heart

The inferior vessels of the heart include the posterior descending artery (PDA) and the posterolateral branches, which supply blood to the inferior wall of the left ventricle.

Anatomy of the Inferior Vessels

The posterior descending artery (PDA) is the primary vessel that supplies the inferior (diaphragmatic) surface of the heart. According to the ACC/AHA guidelines 1, the PDA:

• Runs in the posterior interventricular groove
• Supplies septal perforator branches to the interventricular septum
• Is a key vessel in determining coronary dominance

The posterolateral branches are additional inferior vessels that include:

• Posterolateral segmental artery
• First right posterolateral branch
• Second right posterolateral branch
• Third right posterolateral branch

Coronary Dominance and Inferior Vessel Origin

The origin of the inferior vessels depends on coronary dominance, which is classified into three patterns 1:

1. Right dominance (most common): The PDA and posterolateral branches arise from the right coronary artery (RCA)
2. Left dominance: The PDA and posterolateral branches arise from the left circumflex artery
3. Co-dominant: The RCA supplies the PDA, and the left circumflex artery supplies the posterolateral branches

Clinical Significance of Inferior Vessels

The inferior vessels have important clinical implications:

• In inferior wall myocardial infarction, the occluded vessel is typically either the RCA or left circumflex artery, depending on which provides the PDA 1
• When the RCA is occluded proximally, right ventricular infarction may occur alongside inferior wall infarction 1
• The PDA supplies the inferior interventricular septum through posterior descending septal perforators 1

Anatomical Variations

Several anatomical variations of the inferior vessels exist:

• The anterior interventricular artery (from the left coronary system) may extend to the inferior surface of the heart in approximately 65% of cases 2
• A right inferior diagonal artery may be present in about 20% of hearts 2
• Double posterior descending arteries can occur, though rarely 3
• The posterior descending branch may be deviated rightward relative to the interventricular septum in certain congenital heart conditions 4

Echocardiographic Visualization

When evaluating the inferior vessels by echocardiography, specific views are recommended 1:

• For the distal RCA: Apical 4-chamber (inferior view); subcostal atrial long axis (inferior view)
• For the posterior descending artery: Apical 4-chamber (inferior); subcostal atrial long axis (inferior); precordial long axis (inferior tangential) imaging; posterior interventricular groove

Conclusion

Understanding the anatomy and variations of the inferior vessels is crucial for accurate diagnosis and management of inferior wall myocardial infarction and other cardiac conditions affecting the inferior heart surface.