Anatomy - LAD

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The aortic valve has three cusps:

  • The left coronary cusp, which gives rise to the left coronary artery
  • The right coronary cusp, which gives rise to the right coronary artery
  • The posterior non-coronary cusp, which usually does not give rise to a coronary artery

In most cases, the left coronary artery bifurcates into two branches, namely:

  • The left anterior descending artery (LAD)
  • The ramus circumflexus (RCx), also known as the left circumflex artery (LCx)

Occasionally, a third branch called Ramus intermedius (Int) may arise between the LAD and the RCx.

The LAD courses over the anterior aspect of the heart through the anterior interventricular sulcus (AIVS), an anterior groove in between the right and left ventricles.

The LAD gives off several branches called diagonal branches. These branches course diagonally on the anterolateral portion of the left ventricle. The first diagonal branch is designated as D1; the second diagonal branch is designated as D2; and so on.

The first diagonal branch is used as an anatomic landmark in designating the different segments of the LAD.

  • The segment of the LAD proximal to D1 between the origin of the LAD and the origin of D1 is called the proximal LAD.
  • The most distal 1/3 of the LAD is called the distal LAD.
  • The segment of the LAD between the proximal LAD and distal LAD is the mid-LAD.

As the LAD courses through the anterior interventricular sulcus it gives off several branches called septal perforators (SP), which supply blood to the interventricular septum.

 

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