Normal ECG
The normal ECG has the following characteristics
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Regular rhythm (<10% variation at RR intervals)
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Heart rate of 60-100 bpm
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P waves originating in the sinus node
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Upright in I, II, aVF, and V2-V6 (best seen in II)
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Inverted in aVR
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Variable in III, and aVL
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PR interval between 120-200 msec
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QRS duration of 60-110 msec
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QRS Axis of -30° to 90°
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No pathologic Q waves
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Isoelectric ST segments
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Normal T Waves
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Height <2/3 the size of the preceding R Wave
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In the same direction of the predominant QRS deflection
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Corrected QT interval:
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390-450 msec (men)
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390-460 msec (women)
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