EKG CHANGES IN ISCHEMIA

LOCATING A MYOCARDIAL INFARCTION WITH AN EKG
LOCATION
LEAD
 FACTOIDS
Anterior Wall
V2,V3,V4
 Usually associated with occlusion of the left anterior descending branch of the LCA.
Lateral Wall
I,aVL,V5,V6
 May be a component of a multiple-site infarction.
Usually associated with obstruction of left circumflex artery.
Inferior Wall
II,III,aVF
 Usually associated with RCA occlusion.
Posterior Wall
V7,V8,V9
 Frequently associated with inferior MI. Usually associated with obstruction of RCA and/or left circumflex coronary artery.
Right
Ventricular
Infarction
V4r(5th
intercostal
space, right
mid clavical
line
 Usually accompanies inferior MI due to proximal occlusion of the RCA.
Best diagnosed by 1-2 mm ST elevation in lead V4r.
An important cause of hypotension in inferior MI.
Recognize by jugular venous distension with clear lung fields.
Aggressive therapy is indicated, including: reperfusion, adequate IV fluids for right heart filling, & pacing to maintain A-V synchrony if necessary.
COMMON EKG FORMATIONS
Ischemia=Inverted
T-wave
 Inverted T-wave is symmetrical.
T-waves usually upright in leads I,II, & V2-V6, so check these leads for T-wave inversion.
Injury=Elevated ST
segment
 Signifies and acute process; ST returns to baseline with time.
If ST elevation is diffuse & unassociated with Q-waves or reciprocal ST depression, consider pericarditis.
Location of injury can be determined in the same manner as infarct location.
Usually associated with reciprocal ST depression in other leads.
Infarction=Q-wave
 Small Qs may be normal in V5,V6,I, & aVL.
Abnormal Q must be one small (0.04) and/or if Q-wave deapth is greater than one-third of QRS height in lead III.

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