Coronary Arteries
The coronary arteries arise from the aortic sinuses immediately superior to the aortic valve and provide the primary blood supply to the myocardium.
Primary Branches
- Right Coronary Artery (RCA): Typically supplies the right atrium, right ventricle, SA node (60%), and AV node (80%).
- Left Main Coronary Artery (LMCA): Quickly divides into:
- Left Anterior Descending (LAD): Supplies the anterior wall of the LV, the bundle of His, and the anterior 2/3 of the interventricular septum.
- Left Circumflex (LCX): Supplies the lateral and posterior walls of the left atrium and left ventricle.
Coronary Dominance
| Dominance | Artery supplying the Posterior Descending Artery (PDA) |
|---|---|
| Right Dominant (70–80%) | RCA |
| Left Dominant (10–15%) | LCX |
| Codominant (5–10%) | Both RCA and LCX |
High-Yield Exam Pearl:
The LAD is the most commonly occluded artery, often referred to as “the widowmaker.” Occlusion of the RCA can cause bradycardia or heart block due to its high likelihood of supplying the SA and AV nodes.