Coronary dominance refers to which artery gives rise to the Posterior Descending Artery (PDA).
This dominance determines which vessel supplies the:
- Posterior left ventricular wall (also referred to as the posterobasal wall of the left ventricle)
- Posterior â…“ of the ventricular septum
Right-Dominant Circulation (~80%)
The right coronary artery (RCA) gives rise to PDA.
Meaning the RCA supplies:
- Entire right ventricular free wall
- SA node
- AV node
- Posterior â…“ of ventricular septum
- Posterobasal wall of the left ventricle
Posterior left ventricular wall MI or an infarct involving the ventricular septum?
→ Most likely RCA occlusion
Left-Dominant Circulation (~10%)
The left circumflex (LCx) gives rise to the PDA.
Meaning the LCx supplies:
- Lateral LV wall
- Posterior â…“ of ventricular septum
- Posterobasal wall of the left ventricle
Posterior left ventricular wall MI or an infarct involving the ventricular septum?
→ Most likely LCx occlusion
Co-Dominant Circulation (10–20%)
The RC-A and LC-X give rise to the PDA → shared supply
An infarcted posterior ventricular septum can be due to an occlusion of the LCx or RCA. However, infarct severity can be reduced depending on collateralization.
Why Students Need to Know This
- Dominance determines infarct location
- Influences autopsy interpretation
- Helps understand gross pathology patterns
- Shows up on ASCP-style questions