What is QRS duration on electrocardiography (ECG)?

Updated: Mar 11, 2019
  • Author: Tarek Ajam, MD, MS; Chief Editor: Terrence X O'Brien, MD, MS, FACC  more...
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The QRS duration represents the time for ventricular depolarization. The duration is normally 0.06 to 0.10 seconds. Q waves are inscribed when the initial QRS vector is directed away from the positive electrode. The R wave is the first positive deflection of the QRS complex; its amplitude varies by age, race, and cardiac pathology, and it should increase across the precordium from leads V1 to V5. The negative deflection after the R wave is the S wave.

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