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Advanced 12 Lead ECG Interpretation

Information Covered:

Lead systems and heart surfaces
1. ECG rhythm analysis
  1. Value
  2. Limitations
2. Heart surfaces
  1. Inferior
  2. Left lateral
  3. Precordial
    1. Acute signs of ischemia, injury and necrosispossible early identification of patients with acute myocardial infarction for intervention (thrombolysis PTCA)
    2. 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
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
2. Interpretation of the ECG
  1. Origin of complex
  2. Rate
  3. Rhythm
  4. Clinical significance
3. Arrhythmia originating in the sinus node
  1. Sinus bradycardia
  2. Sinus tachycardia
  3. Sinus arrhythmia
  4. Sinus arrest
4. 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
5. 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)
6. 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
7. 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

Ventricular fibrillation
Ventricular standstill
Asystole
Abnormalities originating within the bundle branch system
1. Incomplete or complete
2. Right bundle branch block
3. Left bundle branch block
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

never use verapamil
if hemodynamic state is stable - consider lidocaine
Pitfalls
1. age is not a differential
2. slower rates may present with stable hemodynamic
3. preexisting BBB prior to onset of the tachycardia
Regularity
1. monomorphic V-tach and SVT are usually very regular and SVT frequently is faster
2. polymorphic V-tach is irregular
Pulseless electrical activity
1. Electrical mechanical dissociation
2. Mechanical impairments to pulsations/ cardiac output
3. Other possible causes
Other ECG phenomena
1. Accessory pathways
2. Preexitation phenomenon
3. Aberration versus ectopy
ECG changes due to electrolyte imbalances
1. Hyperkalemia
2. Hypokalemia
ECG changes in hypothermia

Content Creator: Ariel Wai
CAPCE Course Number: 20-EMTP-F3-7203
Total CE Hours: 1
Level: Advanced
EMT-CE uses the NEMSES guidelines as the foundation for every course outline.

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