Left anterior descending artery

Anatomy

Course

The LAD arises from the left main coronary artery just beyond the pulmonary artery. It advances to the anterior interventricular sulcus, along which it descends to the notch of cardiac apex. A common variant of the LAD, the "wraparound LAD," wraps around the apex and terminates on the posterior wall.

Although rare, multiple anomalous courses of the LAD have been described. These include the origin of the artery from the right aortic sinus.

Branches

The LAD gives off two types of branches: diagonal branches and septal perforators.

• Septal perforators originate from the LAD, normal to the surface of the heart, perforating and supplying the anterior 2/3 of the interventricular septum.
• Diagonals run along the surface of the heart and supply the lateral wall of the left ventricle and the anterolateral papillary muscle.

Segments

• Proximal: from LAD origin to, and including, the origin of the first septal branch (according to some definitions, to the first diagonal, or to whichever comes first).
• Middle: from proximal segment to halfway of remaining distance to apex. A more technical definition is from the proximal segment to the point where the LAD forms an angle, as seen from a right anterior oblique view on angiography, which is often close to the origin of the second diagonal branch.
• Distal: from middle segment to apex, or in some cases beyond.