Pathologic Q waves

(Redirected from Q Waves)


Pathologic Q wave
  • Significant if >1 box wide or if is 1/3 of entire QRS amplitude
  • Early Repolarization:
    • ST Elevation most prominent in lateral precordial leads (V4-6)
      • Lack of reciprocal changes helps to differentiate from STEMI
    • T waves usually broad, tall (>5mm) & upright
    • Limb leads may also have ST elevation, rarely >2 mm


  • Q waves do not always indicate infarction
  • Must distinguish normal septal q waves from pathologic Q waves:
    • Normal septal q wave: <0.04s, low amplitude
    • Abnormal septal q wave: >0.04s in I OR in II, III, AND aVF OR V3, V4, V5, AND V6
  • Q-wave equivalents in the precordial leads:
    • R-wave diminution or poor R-wave progression
    • Reverse R-wave progression (R waves increase then decrease in amplitude)
      • Must distinguish from lead misplacement
    • Tall R waves in V1, V2 (representing "Q waves" from posterior infarction)

Differential Diagnosis

Q Wave (Pathologic)

See Also