EKG Question #16


On the electrocardiogram, which complex indicates ventricular depolarization?


  1. PR interval
    • Rationale:
  2. ST interval
    • Rationale:
  3. QRS interval
    • Rationale:
  4. T-P interval
    • Rationale:



The QRS complex indicates ventricular depolarization which triggers the contraction of the ventricles. The QRS is measured from the end of the PR interval to the end of the S wave. Normal interval is 0.08 – 0.10 seconds. The QRS width is useful in determining origin of the complex (atrial, junctional, ventricular, etc), and may be useful in determining heart block (BBB), electrolyte imbalances, drug toxicities, hypothermia, and other conditions. Variations in high and low voltage may indicate ventricular hypertrophy or pericardial effusions)

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