Which type of arrhythmia would display a regular pattern interrupted by premature beats?

The type of arrhythmia that exhibits a regular pattern interrupted by premature beats is the premature atrial contraction (PAC). PACs occur when an ectopic atrial focus fires before the next scheduled sinus node impulse, leading to an early depolarization of the atria. This early firing results in a regular rhythm that is interrupted by a premature beat, creating a pattern where the normal sinus rhythm is temporarily disturbed by these early atrial contractions.

This behavior is characteristic of PACs, as they can occur in the context of an otherwise regular rhythm. Other arrhythmias like sinus exit block, sinus arrest, and sinus bradycardia do not typically showcase this distinct regular rhythm combined with interruptions. Sinus exit block involves a failure of the sinus node to conduct impulses normally, sinus arrest indicates a complete cessation of impulse generation, and sinus bradycardia refers to a consistently slow heart rate without irregular interruptions caused by additional beats. These distinctions highlight why PACs are identified by the specified pattern of premature beats among a regular rhythm.