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Sinus Rhythm

Sinus Rhythm EKG
ECG features:
  • Default heart rhythm; impulses arise from sinus node
  • Normal Pw axis: 0° to +75°
  • Normal Pw morphology:
    • Upright in I, II-aVF
    • Inverted in aVR
    • Upright or biphasic (positive-negative) in III, aVL, V1-V2
    • Same morphology throughout rhythm strip
  • Regular PP interval varying by less than 160 ms or less than 10 percent
  • Atrial rate: 60-100 BPM in adults (or in normal age-specific range)
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Comments 1

dennis swanson on Thursday, 09 September 2021 10:19

I was always taught one way to recognize a sinus beat was to recognize that the P in lead II was always the largest of the limb leads. I also learned that when P in I was > P in II to suspect a left arm/left leg lead switch. At least once a month or so I'll see an EKG where the P in I is > P in II but when I look to see if there has been a LA/LL switch there is none. The rhythm also turns out to be sinus. You recently commented (sorry, I'm not sure exactly where/when) on the normalcy of the P in I sometimes being > P in II due to its traveling a more horizontal pathway. Very helpful. Thanks

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I was always taught one way to recognize a sinus beat was to recognize that the P in lead II was always the largest of the limb leads. I also learned that when P in I was > P in II to suspect a left arm/left leg lead switch. At least once a month or so I'll see an EKG where the P in I is > P in II but when I look to see if there has been a LA/LL switch there is none. The rhythm also turns out to be sinus. You recently commented (sorry, I'm not sure exactly where/when) on the normalcy of the P in I sometimes being > P in II due to its traveling a more horizontal pathway. Very helpful. Thanks