Recall, as well, that a STEMI is a STEMI is a STEMI. When there is not only anterior ST segment elevation (V3 and V4), but also septal (V1 and V2) and lateral (V5, V6, lead I and lead aVL), an “extensive anterior” MI is said to be present. Now, “high lateral” MIs with ST segment elevation in the limb leads I and aVL can show reciprocal ST segment depression in leads II, III and aVF. If this is the case, then the ST segment elevation will be in V3 to V6 - and not the septal leads.īecause the anatomical opposite of the precordial leads would be posterior leads, which we do not commonly check in this setting, there are no “reciprocal changes” during anterior or septal MIs. When the thrombus is in the mid LAD (after the septal branch), the diagonal branch(es) may or may not be involved. If the thrombus is in the proximal LAD, the septum and lateral walls will often also be involved, in addition to the anterior segments, resulting in ST segment elevation in leads V1 through V6 and perhaps lead I and aVL, as well. We will get to the examples soon, but first we need to understand some more basics of anterior MIs. This results in part of the inferior wall being supplied by the LAD, as well.

To make things more complicated, sometimes the LAD “wraps around” the cardiac apex, which is a common anatomic variant. The septum is represented on the ECG by leads V1 and V2, whereas the lateral wall is represented by leads V5, V6, lead I and lead aVL. Recall that the anterior leads are technically V3 and V4 however, it is common for the septum and/or lateral wall to be involved during anterior MIs, as the LAD supplies septal branches to the interventricular septum and diagonal branches to the lateral wall. An anterior STEMI is usually from acute thrombotic occlusion of the left anterior descending coronary artery - also known as the “widow maker.” This is the big one that carries a high mortality if not treated rapidly. Enlarge Type #1: Anterior ST Segment Elevation MI

Waves 12 complete bundle