Cardiovascular Medicine Book

Coronary Artery Disease

  • Electrocardiogram in Myocardial Infarction

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Electrocardiogram in Myocardial Infarction

Aka: Electrocardiogram in Myocardial Infarction, EKG in Acute MI, EKG in Myocardial Ischemia, EKG in Cardiac Ischemia, EKG Markers of Underlying Coronary Artery Disease, EKG in Acute Coronary Syndrome, Septal Myocardial Infarction EKG Changes, Anterior Myocardial Infarction EKG Changes, Inferior Myocardial Infarction EKG Changes, Lateral Myocardial Infarction EKG Changes, Posterior Myocardial Infarction EKG Changes
  1. See Also
    1. ST Elevation causes
  2. 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
  3. 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
  4. Precautions
    1. The computer over-reads abnormal EKGs
    2. Compare with prior EKGs (Increases Specificity)!
  5. Images
    1. Acute ST Elevation Myocardial Infarction with delayed presentation (ST Elevation and Q waves present)
      1. cv_STEMI_LatePresentation.jpg
  6. 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
  7. Findings: General EKG Changes suggestive of Coronary 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]
    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]
  8. Findings: General EKG Changes suggestive of acute coronary infarction
    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
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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 posterolateral 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
  14. 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

ECG myocardial ischemia (C0474715)

Definition (NCI) An electrocardiographic finding of ST and T wave changes consistent with impaired myocardial perfusion.
Concepts Finding (T033)
SnomedCT 164861001, 164864009, 57740008, 142021007, 142024004
English ECG: myocardial ischaemia, ECG: myocardial ischemia, 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, Myocardial Ischemia by ECG Finding, ECG myocardial ischemia, ECG: myocardial ischaemia NOS (finding), Electrocardiogram finding of ischemia (finding), Electrocardiogram finding of ischemia, ECG: myocardial ischaemia (finding), Electrocardiogram: myocardial ischaemia NOS, Electrocardiogram: myocardial ischemia NOS, Electrocardiogram finding of ischaemia, Electrocardiogram: myocardial ischemia NOS (finding), EKG findings of ischemia, EKG findings of ischaemia, Myocardial Ischemia by EKG Finding, ECG myocardial ischaemia
Spanish hallazgos electrocardiográficos de isquemia (hallazgo), hallazgos electrocardiográficos de isquemia, hallazgo electrocardiográfico de isquemia (hallazgo), ECG: myocardial ischaemia NOS, electrocardiograma: isquemia miocárdica, SAI (hallazgo), electrocardiograma: isquemia miocárdica, SAI, ECG: myocardial ischemia NOS, ECG: isquemia miocárdica, SAI, hallazgo electrocardiográfico de isquemia, ECG: isquemia miocárdica, electrocardiograma: isquemia miocárdica (hallazgo), electrocardiograma: isquemia miocárdica
Sources
Derived from the NIH UMLS (Unified Medical Language System)


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