What is a typical clinical picture feature of sinus arrhythmia?

• A. Irregular pulse
• B. Regular pulse
• C. Palpitations always
• D. Syncope only

Answer: (A)

Sinus arrhythmia is a normal physiologic variation where the heart rate changes with breathing due to autonomic modulation of the sinoatrial node. On inspiration, heart rate tends to speed up; on expiration, it slows down. This causes beat-to-beat intervals to vary, so the pulse feels irregular, even though the rhythm is still originating from the SA node and is otherwise normal. It’s most common in younger, healthy individuals and usually causes no symptoms. Therefore an irregular pulse is the typical clinical picture. Regular pulse wouldn’t reflect the breathing-driven variation, and palpitations or syncope are not typical features of this benign variant.