A premature P wave is referred to as which of the following?

A premature P wave is referred to as which of the following?

• A. PAC
• B. PVC
• C. Second-degree AV block
• D. None of the above

Answer: (A)

The main concept is recognizing a premature atrial contraction, which is identified by a premature P wave. A PAC occurswhen an atrial focus outside the SA node fires early, producing a P wave that appears sooner than the next expected sinus P wave. The QRS complex typically remains narrow because ventricular conduction is usually normal after the atrial impulse. This distinguishes a PAC from a premature ventricular contraction, where there is no preceding P wave and the QRS is typically wide due to ventricular origin. It also distinguishes from a second-degree AV block, where there are dropped beats and variable PR intervals rather than an early, ectopic atrial beat. Therefore, the premature P wave corresponds to a PAC.

The main concept is recognizing a premature atrial contraction, which is identified by a premature P wave. A PAC occurswhen an atrial focus outside the SA node fires early, producing a P wave that appears sooner than the next expected sinus P wave. The QRS complex typically remains narrow because ventricular conduction is usually normal after the atrial impulse.

This distinguishes a PAC from a premature ventricular contraction, where there is no preceding P wave and the QRS is typically wide due to ventricular origin. It also distinguishes from a second-degree AV block, where there are dropped beats and variable PR intervals rather than an early, ectopic atrial beat. Therefore, the premature P wave corresponds to a PAC.