Medical Minute Recap: Posterior EKG

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November 12, 2015 by dailybolusoflr

By: Erin Kane, MD

How do you know you need one?
Reciprocal changes in anteroseptal leads V1-3 – deep, horizontal ST depression

What is the relevant anatomy?
Isolated posterior MI is 3-11% of infarcts
Posterior infarction is present in 15-20% of STEMIs, often in context of lateral or inferior infarction
Usually caused by occlusion of PDA (which is a branch of the RCA in 80% of individuals, otherwise may be via LCx or co-supplied by both – right dominant circulation versus left dominant or codominant)

http://what-when-how.com/nursing/the-cardiovascular-system-structure-and-function-nursing-part-2/

How do you place the leads to get it?
Leads V7-9 are placed on posterior chest wall

http://lifeinthefastlane.com/ecg-library/pmi/

How do you read it?
0.5mm ST segment elevation makes diagnosis of posterior MI

Quick review:
Anatomical relationship of leads
Inferior wall – Leads II, III, and aVF
Anterior wall – leads V1 to V4
Lateral wall – Leads I, aVL, V5, V6

Non-standard leads
Posterior wall – Leads V7 to V9
Right ventricle – stayed tuned for tomorrow’s MM


References
2. Mattu A, Brady W. ECGs for the Emergency Physician 1, BMJ Books 2003.
3. Morris F and WJ Brady. ABC of clinical electrocardiography: Acute myocardial infarction—Part I. BMJ 2002; 324: 831
4. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, Seventh Edition 

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