What rhythm is suggested by regular P waves before each QRS, a rate around 50 bpm, and a normal PR interval?

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Multiple Choice

What rhythm is suggested by regular P waves before each QRS, a rate around 50 bpm, and a normal PR interval?

Regular P waves before each QRS indicate the atrial depolarization is coming from the sinus node, so the rhythm is sinus in origin. A rate around 50 beats per minute places it in the bradycardic range, and a normal PR interval shows the AV node is conducting normally without block. Put together, these features define sinus bradycardia: the sinus node pacing the heart slowly but with preserved AV conduction. If the rhythm were atrial fibrillation, you wouldn’t see discrete P waves and the rhythm would be irregular. If it were atrial flutter, you’d expect a pattern of flutter waves (sawtooth), not regular P waves before each QRS. If it were sinus tachycardia, the rate would be fast rather than slow.

Regular P waves before each QRS indicate the atrial depolarization is coming from the sinus node, so the rhythm is sinus in origin. A rate around 50 beats per minute places it in the bradycardic range, and a normal PR interval shows the AV node is conducting normally without block. Put together, these features define sinus bradycardia: the sinus node pacing the heart slowly but with preserved AV conduction.

If the rhythm were atrial fibrillation, you wouldn’t see discrete P waves and the rhythm would be irregular. If it were atrial flutter, you’d expect a pattern of flutter waves (sawtooth), not regular P waves before each QRS. If it were sinus tachycardia, the rate would be fast rather than slow.

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