I. See Also

  1. ST Elevation causes

II. Advantages

  1. Ischemic EKG changes best acute MI evidence
    1. Applies if symptom onset within last 3 hours
  2. Normal/Nondiagnostic initial EKG predicts low risk

III. Disadvantages

  1. Poor sensitivity for Myocardial Infarction (40-50%)
    1. 3-10% of MI patients have initial normal EKG
    2. 25% of patients with missed MI had misread EKG

IV. Precautions

  1. The computer over-reads abnormal EKGs
  2. Compare with prior EKGs (Increases Specificity)!

V. Images

  1. Acute ST Elevation Myocardial Infarction with delayed presentation (ST Elevation and Q waves present)
    1. cv_STEMI_LatePresentation.jpg

VI. Findings: EKG Markers of underlying CAD

  1. Left Ventricular Hypertrophy
  2. ST segment changes
  3. T Wave changes
  4. Diagnostic Q Waves in 2 contiguous leads
  5. Left Bundle Branch Block or other conduction changes

VII. Findings: General EKG Changes suggestive of Ischemia

  1. Electrocardiogram may be completely normal
  2. ST Elevation or ST depression
    1. Over 1 mm ST changes that are transient with symptoms
    2. Summed ST deviation (sum of affected leads) >2.5 mm
      1. Holmvang (2003) J Am Coll Cardiol 41:905-15 [PubMed] (or open in [QxMD Read])
  3. Deep symmetric T-wave inversion
    1. Occurs in multiple precordial leads
  4. Left main Coronary Artery stenosis marker
    1. aVR ST segment elevation > V1 ST segment elevation
    2. Gaitonde (2003) Am J Cardiol 92:846-8 [PubMed] (or open in [QxMD Read])

VIII. Findings: General EKG Changes suggestive of acute MI

  1. New left ventricular strain pattern
  2. New Left Bundle Branch Block
  3. Q Waves (.04 sec and 1/3 height of R Wave)
    1. Unless isolated in Lead III
  4. T Wave inversion
    1. Unless isolated to Lead III or Lead V1
  5. ST-T elevation (>1mm in limb or precordial leads)
    1. Must have >=2 concordant leads with changes
  6. ST depression in Lead V1, Lead V2 (Posterior MI)
  7. Hyperacute T Waves (over 50% of preceding R)
    1. Must have 2 or more leads with changes

IX. Findings: Septal MI Anatomic Distribution

  1. Electrocardiogram Changes
    1. Lead V1 to lead V2
  2. Distribution
    1. Left Coronary Artery: LAD-Septal Branch
  3. Complications
    1. Infranodal and Bundle Branch Block

X. Findings: Anterior MI Anatomic Distribution

  1. EKG Changes
    1. ST Elevation in lead V2 to lead V4
    2. ST depression in leads II, III, avF (variably present)
  2. Distribution
    1. Left Coronary Artery: LAD-Diagonal branch
  3. Complications
    1. Bad prognosis
    2. High risk of sudden death
    3. High risk of Congestive Heart Failure in first year
    4. Complete Heart Block

XI. Findings: Inferior MI Anatomic Distribution

  1. EKG Changes
    1. ST Elevation in leads II, III, aVF
    2. Q waves in leads III, aVF
    3. ST depression and T Wave inversion in lead aVL (reciprocal change)
  2. Distribution
    1. Right Coronary Artery: Posterior descending branch
  3. Complications
    1. Distended neck veins with clear lungs
    2. Systolic Blood Pressure drops with
      1. Morphine
      2. Nitroglycerin
    3. Right Ventricular Infarction

XII. Findings: Lateral MI Anatomic Distribution

  1. EKG Changes
    1. ST segment elevation in leads V5, V6, I, aVL
    2. ST segment depression in leads V1, V2, V3, III, aVF (reciprocal change)
  2. Distribution
    1. Left Coronary Artery: Circumflex branch
  3. Complications
    1. Left Ventricular Dysfunction
    2. AV nodal block

XIII. Findings: Right Ventricular Infarction Anatomic Distribution (Posterior and Inferior MI)

  1. Standard EKG Changes (similar to anterior MI EKG when rotated 180 degrees)
    1. ST Elevation in leads I and aVF, and lead III more than II
    2. ST depression in leads I, aVL
  2. Right sided EKG
    1. Right Lead Positioning
      1. Right lead V1 at left of Sternum (standard V2 position)
      2. Right lead V2 at right of Sternum (standard V1 position)
      3. Right lead V6 at right lateral chest
    2. Alternative: V4R
      1. Simply move V4 lead to the right chest (5th intercostal space, mid-clavicular line)
    3. Findings
      1. ST Elevation >1mm in V4R
  3. Distribution
    1. Right Coronary Artery: Proximal branches
  4. Complications
    1. Severe and refractory Hypotension in response to nitrates
      1. Treated with fluid bolus and nitrates are contraindicated

XIV. Findings: Posterior Infarction Anatomic Distribution

  1. EKG Changes
    1. ST depression in leads V1 to V4
    2. Tall R Wave (>0.04 seconds) in leads V1 and V2
    3. Interpret V2 by rotating the axis 180 degrees
      1. Tall R Wave rotates to a Q waves
      2. ST depression rotates to ST Elevation
      3. T Wave rotates to T Wave inversion
  2. Distribution
    1. Left Coronary Artery: Circumflex
    2. Right Coronary Artery: Posterior descending
  3. Complications
    1. Left Ventricular Dysfunction

Images: Related links to external sites (from Google)

Ontology: ECG myocardial ischemia (C0474715)

Concepts Finding (T033)
SnomedCT 164861001, 164864009, 57740008, 142024004, 142021007
English EKG findings of ischemia, ECG: myocardial ischaemia, ECG: myocardial ischemia, EKG findings of ischaemia, ECG myocardial ischemia (finding), ECG: myocardial ischemia NOS (finding), EKG findings of ischemia (finding), Electrocardiogram: myocardial ischaemia, Electrocardiogram: myocardial ischemia (finding), Electrocardiogram: myocardial ischemia, ECG: myocardial ischaemia NOS, ECG: myocardial ischemia NOS, Electrocardiogram finding of ischemia, Electrocardiogram finding of ischaemia, Electrocardiogram finding of ischemia (finding), ECG: myocardial ischaemia NOS (finding), ECG: myocardial ischaemia (finding), Electrocardiogram: myocardial ischaemia NOS, Electrocardiogram: myocardial ischemia NOS, Electrocardiogram: myocardial ischemia NOS (finding), ECG myocardial ischaemia, ECG myocardial ischemia
Spanish hallazgos electrocardiográficos de isquemia (hallazgo), ECG: myocardial ischemia, ECG: myocardial ischaemia, ECG: myocardial ischaemia NOS, hallazgo electrocardiográfico de isquemia (hallazgo), hallazgo electrocardiográfico de isquemia, hallazgos electrocardiográficos de isquemia, ECG: myocardial ischemia NOS, ECG: isquemia miocárdica, SAI, ECG: isquemia miocárdica, electrocardiograma: isquemia miocárdica (hallazgo), electrocardiograma: isquemia miocárdica, SAI (hallazgo), electrocardiograma: isquemia miocárdica, SAI, electrocardiograma: isquemia miocárdica

Ontology: EKG CHANGE MYOCARDIAL INFARCTION (C0743418)

Concepts Disease or Syndrome (T047)
English EKG CHANGE MYOCARDIAL INFARCTION