EKG

General Interpretation

Rapid Review

  • Background
    • A basic, systematic approach to interpreting the EKG includes determination of Rate, Rhythm, Axis, Hypertrophy, Intervals, and Infarction
  • Findings
    • Rate
      • Normal
      • Tachycardia
      • Bradycardia
    • Rhythm
      • Regular
      • Regularly Irregular
      • Irregularly Irregular
    • Axis
      • Normal Axis
      • Left Axis Deviation
      • Right Axis Deviation
      • Extreme Right Axis Deviation
    • Hypertrophy
      • Left Atrial Enlargement
      • Right Atrial Enlargement
      • Left Ventricular Hypertrophy
      • Right Ventricular Hypertrophy
    • Intervals
      • Shortened PR
      • Prolonged PR
      • Widened QRS
      • Prolonged QT
    • Ischemia
      • Q-Waves
      • ST-Segment Elevation
      • ST-Segment Depression
      • Hyperacute T-Waves
      • Inverted T-Waves

Pearls

  • Be systematic in your approach to EKGs. Avoid the temptation to skip directly into looking for ST segment changes. 
  • Axis deviation is initially interpreted using the Quadrant Method (evaluating Lead I and aVF). If there are signs of a possible left axis deviation, this can be confirmed as pathological or physiological using the Three Lead analysis (evaluating Lead I + aVF + Lead II )
Video Credit: Anna Pickens

Tachyarrhythmias

Rapid Review

  • Background
    • Defined as any EKG with a rate of > 100 bpm. Further divided based mechanism/etiology.
  • Common Types
    • Sinus Tachycardia
    • Atrial Fibrillation
    • Atrial Flutter
    • Multifocal Atrial Tachycardia
    • Supraventricular Tachycardia
    • Ventricular Tachycardia

Pearls

  • EKG machines tend to overcall atrial fibrillation. Always perform your own evaluation of the the rate/rhythm.
  • If the rate is too fast to interpret the underlying rhythm, you can increase the paper speed on the EKG machine (ex. from 25 mm/sec to 50 mm/sec) to stretch out the rhythm and make it easier to evaluate.
Video Credit: Strong Medicine

Bradyarrhythmias

Rapid Review

  • Background
    • Defined as any rhythm < 60 bpm. Further divided based on mechanism/etiology. 
  • Common Types
    • Sinus Bradycardia
    • Junctional Bradycardia
    • Sinus Arrest
    • AV Nodal Blocks
      • 1st Degree
      • 2nd Degree, Mobitz Type I (Wenckebach)
      • 2nd Degree, Mobitz Type II 
      • 3rd Degree

Pearls

  • Evaluating the QRS length can help determine the location of the conductive disease in bradycardia rhythms. If the QRS length is narrow ( < 120ms), the problem is likely in a proximal (SA or AV node).  
  • If the patient is unstable, do not spend too long identifying the etiology of the bradycardia. The initial treatment (transcutaneous pacing/atropine) will be the same regardless. 
Video Credit: Crazy Medicine

Ischemia/Infarction

Rapid Review

  • Background
    • Cardiac ischemia and/or infarction can be diagnosed by analyzing the QRS complexes, ST segments, and T-waves on a 12-lead ECG. 
  • Common Findings
    • Ischemia
      • St-Segment Depression
      • T-Wave Flattening or Inversion
      • Hyperacute T-Wave
    • Infarction
      • ST-Segment Elevation
      • LBBB (If meets Sgarbossa criteria)

Pearls

  • Computer EKG interpretation has poor sensitivity rates for both STEMI diagnosis and STEMI equivalents.
  • Although we’re traditionally taught to only evaluate for STEMI on EKG, we should instead be looking for “OMI” (occlusive myocardial infarction). This includes other EKG findings that may identify other intervenable occlusions, such as bifascicular block, hyperacute T-waves, diffuse ST segment depression w/ aVR elevation, etc.
Video Credit: Strong Medicine