Anatomy - Determining the site of occlusion in acute inferior wall infarction

The ECG tracing on the right shows an inferior wall infarction secondary to an occlusion in the RCA. Note that the amplitude of ST elevation is greater in lead III than in lead II.

  • If the amplitude of ST elevation is greatest in lead III, this is suggestive of an inferior wall myocardial infarction secondary to RCA occlusion
  • If the amplitude of ST elevation is greatest in lead II, this is suggestive of an inferior wall myocardial infarction secondary to RCx occlusion

If the amplitudes of ST elevation in leads II and III are of the same size, the clinician can determine the site of occlusion by following these steps:

  1. Determine the sum of the amplitudes of ST deviation (in mm) in leads V1, V2, and V3
  2. Divide the number obtained in #1 by the sum of the amplitudes of ST deviation in leads II, III, and aVF
  3. A quotient greater than 1 is suggestive of an RCx occlusion while a quotient less than or equal to 1 is suggestive of an occlusion in the RCA

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player

Click here to enlarge

 

Back to top