True post wall MI

定義:
    V4-V6 改做 V7-V9
    A posterior wall MI occurs when posterior myocardial tissue (now termed inferobasilar), usually supplied by the posterior descending artery (a branch of the right coronary artery in 80% of individuals), acutely loses blood supply due to intracoronary thrombosis in that vessel. 
     This frequently coincides with an inferior wall MI due to the shared blood supply.

EKG:
  1) V1-V4 ST segment depression (not elevation) in the septal and anterior precordial leads (V1 to V4). 
      This occurs since these ECG leads will see the MI backwards (since the leads are placed anteriorly, but the myocardial injury is posterior).

  2) R波 on V1 or V2 變高 (The ratio of the R wave to the S wave in leads V1 or V2 is > 1)

  3) V7-V9 ST elevation in the posterior leads of a posterior ECG (leads V7 to V9). 
       Suspicion for a posterior MI must remain high, especially if inferior ST elevation is also present.

  4) ST elevation in the inferior leads may be seen if an inferior MI is also present.