Occlusion first diagonal branch

In occlusion of OM branch (isolated involvement of the lateral wall), a flattened or negative T wave maybe observed in V5-V6, and frequently in I and VL. In case of occlusion of first diagonal (involvement of mid-anterior and lateral wall), the negative T wave is usually seen in VL and I and sometimes in II, III and VF, but usually is not evident in V5-V6. 

The LAD occlusion may be located (a) above the first diagonal (Dl) and the first septal (SI) branches, (b) proximal to Dl but not to SI branches, (c) distal to both the SI and Dl branches, (d) proximal to SI but not to Dl branch, (e) LAD occlusion encompassing the diagonal branches but not the septal branches or just a selective D1-D2 occlusion and (f) LAD occlusion encompassing the septal branches... 

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