see: [[ACS]] for other ECG examples and related questions. Also [[STEMI equivalents]], [[Subtle T wave findings acute ischemia]], and [[STEMI mimics]] > [!Key Points] > - up to 6% of ECG in acute MI is normal > - I and aVL are lateral leads > - baseline of ECG is the TP segment, measure ST elevation from here # ECG Change basics - ST elevation → injury pattern - Q waves → infarcted tissue - **significant Q wave =** 1 small box (40ms) wide and 1/3 - 1/4 size of entire QRS - can develop within hours - large Q waves likely completed infarct - ST depression in contiguous leads → ischaemia or infarction - T-wave inversion → ischaemia - lower specificity and morbidity # Anterior MI - usually ==LAD occlusion== - STE in V1-6 - **Septal**: v1-v2 - **anterioseptal:** v1-v4 - **anteriolateral:**: STE in v3-v6, I, aVL ![[Pasted image 20240115214616.png|LAD STEMI]] > remember that leads I and aVL are lateral leads ("high lateral") that are **contiguous** ![[Pasted image 20230515223819.png| STE in I and aVL, "high lateral STEMI"]] ## Lateral MI - can be from circumflex, branch of LAD ![[Pasted image 20230515230000.png| note STE in v5, v6, I, aVL]] # Inferior MI - usually ==RCA occlusion==, *sometimes* ==LCx== - STE II, III, aVF - often reciprocal changes in aVL > always consider posterior and/or right ventricular involveemnt > - 1/3 of inferior MIs will extend to posterior > - 1/3 will extend to the right ventricle ## right ventricular see also: [[ACS#right ventricular]] > - inferior where STE in III > II, STE in V1 > V2, STD in V2 and not V1 > - STE in V1 and STD in V2 is highly **specific** for RV infarction ![[Pasted image 20230516000906.png| STD I, aVL, STD v2, STE v1, STE in III> II, classic for Inferior-right ventricular MI]] > if you knock out the RV, then the only thing getting blood to the LV is your preload.