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Table 113-2

Differential Diagnosis of Q Waves (with Selected Examples)

Physiologic or positional factors

  1. Normal “septal” Q waves
  2. Left pneumothorax or dextrocardia

Myocardial injury or infiltration

  1. Acute processes: myocardial infarction, myocarditis, hyperkalemia
  2. Chronic processes: cardiomyopathy, amyloid, sarcoid, scleroderma, myocardial tumor

Ventricular hypertrophy/enlargement

  1. Left ventricular (poor R-wave progression)a
  2. Right ventricular (reversed R-wave progression)
  3. Hypertrophic cardiomyopathy

Conduction abnormalities

  1. Left bundle branch block
  2. Wolff-Parkinson-White patterns

a Small or absent R waves in the right to midprecordial leads.

Source: Modified from Goldberger AL: Myocardial Infarction: Electrocardiographic Differential Diagnosis, 4th ed. St. Louis, Mosby-Year Book, 1991.