Sinus pause/arrest is characterized by which of the following?

• A. No P waves and irregular QRS complexes
• B. P waves present before each QRS with normal PR (0.12–0.20 s) and QRS 0.10 s or less
• C. P waves present before each QRS with normal PR, but QRS is wide
• D. P waves absent with wide QRS

Answer: (C)

Sinus pause/arrest means the SA node temporarily stops firing, so there’s a gap in atrial impulses. When the impulse resumes, it still starts in the atria and is conducted to the ventricles. That shows up as P waves that precede each QRS, with a normal PR interval, even though the QRS width may be widened if there’s a concurrent intraventricular conduction abnormality (like a bundle-branch block). The key point is the rhythm remains of sinus origin, evidenced by P waves before QRS, rather than arising from a non-sinus source. Patterns with no P waves or with P waves not followed by normal QRS would point to other rhythms, such as junctional or ventricular origins.