Rhythm InterpretationQuestion 23 of 100
A regular strip at 68 beats per minute has one upright P wave before every narrow QRS, and every PR interval measures 0.28 second. What is this rhythm?
a.Normal sinus rhythm
b.Sinus rhythm with a first-degree AV block
c.Second-degree AV block, Mobitz II
d.Third-degree AV block
Explanation
A PR interval that is constant but longer than 0.20 second defines first-degree AV block, in which every impulse still reaches the ventricles but is delayed. Normal sinus rhythm requires a PR of 0.12 to 0.20 second. Mobitz II drops beats without lengthening the PR, and third-degree block shows no consistent relationship between P waves and QRS complexes at all.
Practice all 100 questions free — no signup required.
Related questions on this topic
- A telemetry strip suddenly shows chaotic, irregular waves of varying height with no identifiable P waves, QRS complexes, or T waves. What should the technician do first?
- A monitor shows a nearly flat line with no waveforms in two different leads and the patient is unresponsive with no pulse. What is this rhythm?
- A strip shows wide QRS complexes at a regular rate of 32 beats per minute with no P waves. What is this rhythm called?
- A strip shows PR intervals of 0.18, 0.24, 0.32 second, then a P wave with no QRS after it, and the pattern repeats. What is this rhythm?
- A strip shows a constant PR interval of 0.20 second on conducted beats, but every third P wave is suddenly not followed by a QRS complex. What is this rhythm?
- A strip shows a regular ventricular rhythm at 40 beats per minute with wide QRS complexes, regular P waves at 80 per minute, and no consistent relationship between the P waves and the QRS complexes. What is this rhythm?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against NHA Certified EKG Technician (CET) Exam · How we review