LAD (Left Anterior Descending Artery)

The left anterior descending artery is a branch of the left main coronary artery. It runs down the front of the heart in the groove between the left and right ventricles toward the apex, supplying much of the anterior left ventricle and septum. Because it lies on the anterior surface of the heart, it sits directly beneath the left breast and chest wall.

The left anterior descending artery supplies blood to the front wall of the heart, including much of the left ventricle.

In left-sided tangents the mid and distal LAD often lies at the field edge. The DEGRO review points out that the mean heart dose can be low while parts of the LAD receive a much higher dose, and describes angiography studies that found coronary narrowing concentrated in these high-dose segments. Zureick 2022 linked LAD dose to cardiac events.

That is why some protocols set an LAD limit alongside the heart limits — usually a mean or a maximum dose. Deep-inspiration breath hold moves the heart away from the chest wall and can reduce LAD dose. Published LAD limits apply to left-sided treatment. When the internal mammary nodes are treated, their authors note the limits may not be achievable, and target coverage has to be weighed against LAD dose.

Feng 2011 describes the LAD as starting from the left coronary artery and running in the groove between the right and left ventricles (the interventricular groove). If it is hard to see, a narrower window helps (level 50, width 150 in the atlas).

Even after training with the atlas, observers in Feng's study overlapped with the reference LAD contour only about 62% of the time on average, so expect variation and take care with this structure.