Sinus bradycardia is characterized by all of the following EXCEPT:

Sinus bradycardia is characterized by all of the following EXCEPT:

• A. A regular pulse of less than 60 beats per minute with P waves in front of QRS complexes
• B. P=R interval of 0.06 - 0.12 seconds
• C. QRS interval of 0.04 - 0.11 seconds
• D. P:QRS ratio of 1:1

Answer: (B)

Sinus bradycardia is a slow but otherwise normal sinus rhythm where each beat is initiated by the sinus node and conducts normally to the ventricles. The hallmark features are a regular rhythm, rate below 60 bpm, P waves that precede every QRS, and a 1:1 P:QRS relationship with a narrow QRS complex (typically 0.04–0.11 seconds). The PR interval in a normal sinus rhythm should be within about 0.12–0.20 seconds. The option stating a P–R interval of 0.06–0.12 seconds is not consistent with a normal sinus rhythm because the PR interval would be too short; this makes it the statement that does not fit sinus bradycardia. The other statements align with the expected features: regular rhythm with a rate under 60, P waves before each QRS, P:QRS 1:1, and a normal (narrow) QRS.

Sinus bradycardia is a slow but otherwise normal sinus rhythm where each beat is initiated by the sinus node and conducts normally to the ventricles. The hallmark features are a regular rhythm, rate below 60 bpm, P waves that precede every QRS, and a 1:1 P:QRS relationship with a narrow QRS complex (typically 0.04–0.11 seconds). The PR interval in a normal sinus rhythm should be within about 0.12–0.20 seconds. The option stating a P–R interval of 0.06–0.12 seconds is not consistent with a normal sinus rhythm because the PR interval would be too short; this makes it the statement that does not fit sinus bradycardia. The other statements align with the expected features: regular rhythm with a rate under 60, P waves before each QRS, P:QRS 1:1, and a normal (narrow) QRS.