 Coronary dominance

Coronary dominance classifies coronary arterial branching according to a stated anatomical criterion, commonly the origin of the posterior descending artery. A right-coronary origin is termed right dominant; a left-coronary origin through the circumflex artery is termed left dominant. The label does not state which ventricle is the systemic pump.

A primary anatomical study injected radiopaque medium into 200 human hearts and examined the preparation directly and by X-ray. It classified 178 as right dominant using posterior arterial origin, and described additional branching variation within that category.^[ref]

The sample proportion is $178/200=0.89$. The remaining 22 specimens cannot be assigned to more detailed categories merely by subtracting from the total; their individual routes and the classification rules must be examined. A study using an additional shared-supply category can also require a more detailed rule than a two-way label.

The useful interpretation is topological. The route to the posterior descending artery can pass through the right coronary artery or through the left coronary artery and its circumflex artery. A finding upstream of that branch therefore has different downstream connections in the different patterns.

Even within a dominance category, branch size and supplied territory can vary. The term does not specify every arterial diameter, flow rate or tissue region. For physiological interpretation, the actual route must be combined with coronary blood flow and an appropriate territory definition rather than substituted for them.