Abnormal Q waves

Abnormal Q waves

1. Morphology

   • QR Wave
   • Qr Wave
   • QS Wave
     • Also due to LBBB, LVH, cor pulmonale or cardiomyopathy
       • V1 to V3
   • qR Wave

2. Normal Q waves

   • rapid depolarisation of thin septal wall between two ventricles
   • Maybe found in most leads
   • very short and low amplitude
   • Lead III, aVR, V1

3. Location

   • Lead V2 & V3
   • Leads I, II, aVL, aVF, or V4 to V6
     • > or = 0.03 sec
     • 2 contiguous leads
   • Lead V4
     • > 1mm deep or at least 0.02 sec or > Q wave in V5
   • Lead aVL
     • > 0.04 sec or > 50% amplitude of QRS complex with upright P wave
   • Lead III
     • > or = 0.04 sec

4. Q Wave Equivalents

   • tall R waves in leads V1 & V2
     • Posterior infarction
   • Poor R wave progression
     • localised R wave diminution
     • localised R wave diminution
   • reverse R wave progression
     • R waves decrease in amplitude from V1 to V4

5. dead or necrotic tissue act as an "electrical window" transmitting depolarising forces (R wave) from opposite position of heart

   • Completely developed in 8-12 hours of occulsion
   • 10% patients don't develop until 3-11 days after MI

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