Premature atrial beats occur when an ectopic atrial focus fires early. Which statement best describes the P waves in these beats?

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Multiple Choice

Premature atrial beats occur when an ectopic atrial focus fires early. Which statement best describes the P waves in these beats?

Premature atrial beats come from an ectopic atrial focus that fires before the next expected beat. That makes the P wave occur earlier in the cycle. If the ectopic focus is near the sinus node, the atrial activation pattern is very similar to normal sinus activation, so the P waves look like the regular sinus P waves, just earlier. The QRS complex remains normal because ventricular conduction isn’t altered. So the best description is that an early ectopic atrial impulse produces a P wave that resembles sinus rhythm. Absent P waves would point to ventricular ectopy, P waves after the QRS suggest retrograde atrial activation, and inverted P waves indicate a different atrial origin or conduction pattern—not the near-SAN premature atrial beat.

Premature atrial beats come from an ectopic atrial focus that fires before the next expected beat. That makes the P wave occur earlier in the cycle. If the ectopic focus is near the sinus node, the atrial activation pattern is very similar to normal sinus activation, so the P waves look like the regular sinus P waves, just earlier. The QRS complex remains normal because ventricular conduction isn’t altered. So the best description is that an early ectopic atrial impulse produces a P wave that resembles sinus rhythm. Absent P waves would point to ventricular ectopy, P waves after the QRS suggest retrograde atrial activation, and inverted P waves indicate a different atrial origin or conduction pattern—not the near-SAN premature atrial beat.

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