In approximately 80% of people, the right coronary artery supplies the posterior surface and the interventricular septum. This configuration is called a what heart?

• A. Dominant left
• B. Dominant right
• C. Balanced
• D. Mixed

Answer: (B)

The key idea is coronary artery dominance, which describes which artery primarily supplies the posterior descending artery (PDA) and the posterior part of the interventricular septum. In about 80% of people, the right coronary artery gives rise to the PDA, so the RCA is the dominant vessel and the heart is considered right-dominant. This means the RCA supplies the posterior surface and the posterior septum.

If the left coronary system (typically the left circumflex) were to provide the PDA, the heart would be left-dominant. When the PDA receives contributions from both arteries, the circulation is described as codominant or balanced, with no single artery truly dominant.

So the described pattern—PDA and posterior septum supplied mainly by the right coronary artery in the majority of people—fits a right-dominant heart.