Which coronary artery supplies the majority of the left ventricle?

Which Coronary Artery Supplies the Majority of the Left Ventricle?

The left anterior descending (LAD) artery supplies the majority of the left ventricle. 1

Coronary Artery Anatomy and Distribution

The left ventricle receives its blood supply primarily through the following coronary arteries:

1. Left Anterior Descending (LAD) Artery:

   • Originates from the left main coronary artery
   • Supplies the:
     • Anterior wall of the left ventricle
     • Anterolateral wall (via diagonal branches)
     • Interventricular septum (via septal perforators)
     • Apex of the heart (in most cases)
   • The LAD typically supplies 45-55% of the left ventricular myocardium 1

2. Circumflex Artery:

   • Also originates from the left main coronary artery
   • Supplies the:
     • Lateral wall of the left ventricle (via obtuse marginal branches)
     • Posterior wall (in left-dominant circulation)
   • Typically supplies 15-25% of the left ventricle

3. Right Coronary Artery (RCA):

   • Supplies primarily the right ventricle
   • In right-dominant circulation (most common), the posterior descending artery (PDA) branches from the RCA and supplies:
     • Inferior wall of the left ventricle
     • Posterior third of the interventricular septum
   • Supplies approximately 25-35% of the left ventricle in right-dominant circulation

4. Posterior Descending Artery (PDA):

   • Arises from the RCA in right-dominant circulation (85-90% of people)
   • Arises from the circumflex in left-dominant circulation (10-15% of people)
   • Supplies the inferior and posterior portions of the left ventricle

Clinical Significance

The extensive distribution of the LAD explains why proximal LAD occlusions are often called "widow-makers" and carry significant morbidity and mortality. Research has shown that:

• LAD length is a prognostic factor in anterior wall myocardial infarctions 2
• "Wrap-around" LADs (those that extend around the apex) supply even more myocardium and are associated with worse outcomes when occluded 2, 3
• In patients with left coronary dominance, the LAD is typically longer and wraps around the apex in approximately 87% of cases, compared to only 47% in right-dominant circulation 3

Anatomical Variations

Several variations in coronary anatomy can affect the distribution of blood supply to the left ventricle:

• In approximately 77.7% of people, the apex is totally supplied by the LAD
• In 12.1%, the apex receives dual blood supply from both LAD and PDA
• In 10.2%, the LAD terminates before the apex, which is then supplied by the PDA 4

These variations are important to recognize when interpreting cardiac imaging and planning interventions for coronary artery disease.

In summary, while all three major coronary arteries contribute to left ventricular perfusion, the LAD supplies the largest portion of the left ventricular myocardium, making it the correct answer to this question.