Circumflex artery

Last revised by Dr Mostafa El-Feky on 15 Jan 2022

The circumflex artery (Cx) is one of the two major coronary arteries that arise from the bifurcation of the left main coronary artery (the other branch being the left anterior descending (LAD) artery).

The circumflex artery can be referred to by multiple terms:

  • circumflex artery (Cx or CX)
  • ramus circumflex artery (RCx or RCX)
  • left circumflex artery (LCx or LCX)

Often it is colloquially called the 'circ'.

The artery travels in the left atrioventricular groove between the left ventricle and left atrium. The artery is located in the epicardium.

The circumflex artery gives off up to three obtuse marginal branches and may give off a left posterolateral branch and may supply the inferior interventricular artery (see variant anatomy below).

In angiography and CTCA, the LCx is often described as having proximal and distal segments:

  • proximal segment: from the LMCA bifurcation (LCx origin) to the origin of the first marginal artery (M1)
  • distal segment: from the M1 origin to the termination

Branches of the circumflex artery supply the lateral and posterolateral walls of the left ventricle.

Most hearts are right dominant where the posterior descending artery (PDA) is supplied by the right coronary artery (RCA). However up to 20% of hearts may be left dominant, where the PDA is supplied by the LAD or LCx or codominant, where a single or duplicated PDA is supplied by branches of both the RCA and LAD/LCx.

For a more in depth discussion of coronary dominance, see the article coronary arterial dominance.

  • coronary artery disease: occlusion of the circumflex artery leading to myocardial infarction or sudden cardiac death

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Cases and figures

  • Figure 1: coronary arteries (creative commons illustration)
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  • Figure 2
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  • Case 1: normal coronary angiogram (DSA)
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  • Case 2: normal CTCA
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  • Case 3: circumflex artery arising from right coronary sinus
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