12 Lead ECG Interpretation

12 Lead ECG Interpretation

Information Covered:

  1. Lead systems and heart surfaces
    1. ECG rhythm analysis
      1. Value
      2. Limitations
    2. Heart surfaces
      1. Inferior
      2. Left lateral
      3. Precordial
    3. Acute signs of ischemia, injury and necrosis
  2. possible early identification of patients with acute myocardial infarction for intervention (thrombolysis PTCA)
  3. the role of out-of-hospital 12-lead ECG is not universally available but is appropriate in most EMS settings with proper medical oversight
  4. Advantages/ disadvantages
  5. ST segment elevation
    1. height, depth and contour
    2. ST (acute changes)
      1. anterior wall -- significant ST elevation in V1- V4 may indicate anterior involvement
      2. inferior wall -- significant ST elevation in II, III and aVF may indicate inferior involvement
    3. ST segment depression in eight or more leads
    4. ST segment elevation in aVR and V1
  6. Q waves
    1. depth, duration and significance
      1. greater than 5 mm, greater than .04 seconds
      2. may indicate necrosis
      3. may indicate extensive transient ischemia
  7. Cardiac arrhythmias
    1. Approach to analysis
      1. P wave
        1. configuration
        2. duration
        3. arial rate and rhythm
      2. P-R (P-Q) interval
      3. QRS complex
        1. configuration
        2. duration
        3. ventricular rate and rhythm
      4. S-T segment
        1. contour
        2. elevation
        3. depression
      5. Q-T interval
        1. duration
        2. implication of prolongation
      6. Relationship of P waves to QRS complexes
        1. consistent
        2. progressive prolongation
        3. no relationship
      7. T waves
      8. U waves
  8. Interpretation of the ECG
    1. Origin of complex
    2. Rate
    3. Rhythm
    4. Clinical significance
  9. Arrhythmia originating in the sinus node
    1. Sinus bradycardia
    2. Sinus tachycardia
    3. Sinus arrhythmia
    4. Sinus arrest
  10. Arrhythmias originating in the atria
    1. Premature atrial complex
    2. Atrial (ectopic) tachycardia
    3. Re-entrant tachycardia
    4. Multifocal atrial tachycardia
    5. Atrial flutter
    6. Atrial fibrillation
    7. Atrial flutter or atrial fibrillation with junctional rhythm
    8. Atrial flutter or atrial fibrillation with pre-excitation syndromes
  11. Arrhythmias originating within the AV junction
    1. First degree AV block
    2. Second degree AV block
      1. Type I (Wenkebach)
      2. Type II/ infranodal (Classical)
    3. Complete AV block (third degree block)
  12. Arrhythmias sustained or originating in the AV junction
    1. AV nodal re-entrant tachycardia
    2. AV reciprocating tachycardia
      1. narrow
      2. wide
    3. Junctional escape rhythm
    4. Premature junctional complex
    5. Accelerated junctional rhythm
    6. Junctional tachycardia
  13. Arrhythmias originating in the ventricles
    1. Idioventricular rhythm
    2. Accelerated idioventricular rhythm
    3. Premature ventricular complex (ventricular ectopic)
      1. R on T phenomenon
      2. paired/ couplets
      3. multiformed
      4. frequent uniform
    4. "Rule of bigeminy" pertaining to precipitating ventricular arrhythmias
    5. Ventricular tachycardia
      1. Monomorphic and polymorphic
  14. Ventricular fibrillation
  15. Ventricular standstill
  16. Asystole
  17. Abnormalities originating within the bundle branch system
    1. Incomplete or complete
    2. Right bundle branch block
    3. Left bundle branch block
  18. Differentiation of wide QRS complex tachycardia
    1. Potential causes
      1. supraventricular tachycardia with bundle branch block
      2. accessory pathways
    2. Differentiation
      1. physical evaluation
        1. Cannon “A” waves
        2. vary intensity of first heart tone
        3. beat to beat changes in blood pressure
      2. ECG differences
        1. aberration as a result of premature atrial complex
          1. identify PAC in previous ST segment or T wave
          2. sudden change in rate with bundle branch aberration
          3. concealed retrograde conduction
          4. right bundle branch refractoriness - may be time dependent
          5. compare with previous ECG, when available
        2. RBBB aberration - V1 – positive
          1. biphasic lead I with a broad terminal S-wave
          2. triphasic QRS in V4
        3. LBBB aberration - V1 – negative
          1. monophasic notched lead I
          2. slurred, notched or RSr’ in lead V4, V5, or V6
        4. Concordant precordial pattern
          1. totally negative precordial pattern is diagnostic of ventricular tachycarida
          2. totally positive precordial pattern is suggestive of ventricular tachycardia
        5. Preexisting BBB prior to onset of tachycardia (by history)
      3. Other considerations
        1. When in doubt:
          1. cardioversion when hemodynamic state is compromised or changing as evidenced
  19. never use verapamil
  20. if hemodynamic state is stable - consider lidocaine
  21. Pitfalls
    1. age is not a differential
    2. slower rates may present with stable hemodynamic
    3. preexisting BBB prior to onset of the tachycardia
  22. Regularity
    1. monomorphic V-tach and SVT are usually very regular and  SVT frequently is faster
    2. polymorphic V-tach is irregular
  23. Pulseless electrical activity
    1. Electrical mechanical dissociation
    2. Mechanical impairments to pulsations/ cardiac output
    3. Other possible causes
  24. Other ECG phenomena
    1. Accessory pathways
    2. Preexitation phenomenon
    3. Aberration versus ectopy
  25. ECG changes due to electrolyte imbalances
    1. Hyperkalemia
    2. Hypokalemia
  26. ECG changes in hypothermia

 

Content Creator: Ariel Wai

CAPCE Course Number: 17-EMTP-F3-7204

Total CE Hours: 1

Level: Advanced

EMT-CE uses the NEMSES guidelines as the foundation for every course outline.