 Circumflex artery

The circumflex artery is a major branch of the left coronary artery that follows the coronary sulcus around the left side of the heart. It gives branches including a left marginal branch.^[ref] It is distinct from the left anterior descending artery, the other typical major left-coronary branch.

Its route can also be relevant to posterior supply. When the posterior descending artery originates through the circumflex system, that connection contributes to a left-dominant coronary dominance pattern. A posterior branch name therefore does not uniquely identify a right-coronary origin.

The network distinction helps interpret where a finding lies. A segment before the left-coronary bifurcation is upstream of both major branches. A segment within the circumflex route is downstream of that split. These are different anatomical positions even though both may be described broadly as left-coronary findings.

An original two-outlet model assigns left-coronary flow $Q_L=Q_A+Q_C$, where $Q_A$ is anterior-branch flow and $Q_C$ circumflex flow. Knowing $Q_L=180\mathrm{mL}\mathrm{mi}{\mathrm{n}}^{-1}$ does not determine $Q_C$: pairs $(Q_A,Q_C)=(110,70)$ and $(90,90)$ produce the same total. An additional branch-sensitive observation is required.

Actual arterial mapping can be examined by selective contrast imaging. The primary Judkins method used selective catheterization with serial and cine recording.^[ref] Such observation identifies a route and its geometry; interpreting coronary blood flow or oxygen supply also requires the relevant physiological measurements.