Sinus Rhythm Interpretation Flashcards

Normal sinus rhythm requires which set of criteria?

Answer: Regular P waves upright in II and inverted in aVR, constant PR 120-200 ms, rate 60-100 bpm, narrow QRS

Normal sinus rhythm requires an SA node origin (upright P in II, inverted in aVR), normal PR interval (120-200 ms), heart rate 60-100 bpm, and narrow QRS complexes.

Sinus bradycardia is defined as sinus rhythm at a rate below which threshold?

Answer: 60 bpm

Sinus bradycardia is defined as a normal sinus rhythm (SA node origin) at a rate less than 60 bpm. All other criteria for sinus rhythm remain intact.

Sinus arrhythmia is best described as which pattern?

Answer: Irregular R-R intervals that vary with respiration, with all other sinus rhythm criteria intact

Sinus arrhythmia is a normal variant where heart rate increases with inspiration and decreases with expiration, producing slight R-R interval variation while maintaining normal sinus P waves and PR intervals.

A sinus pause is defined as an absence of the expected sinus beat lasting at least how long?

Answer: Two or more seconds (or twice the preceding R-R interval)

A sinus pause is defined as an unexpected absence of a P wave lasting at least 2 seconds (or more than twice the preceding R-R interval), indicating a failure of the SA node to generate an impulse.

A patient's rhythm strip shows a regular rhythm at 55 bpm with upright P waves in lead II and a PR interval of 160 ms. How should this rhythm be classified?

Answer: Sinus bradycardia

Upright P waves in II, constant normal PR interval (160 ms is within 120-200 ms), and rate below 60 bpm with regular rhythm meets criteria for sinus bradycardia specifically.

Sinus tachycardia is most appropriately managed by which approach?

Answer: Identifying and treating the underlying cause (fever, pain, hypovolemia, anxiety, hyperthyroidism)

Sinus tachycardia is almost always a secondary, compensatory response — the appropriate treatment is to identify and address the underlying physiological cause, not to suppress the tachycardia directly.