Rhythm InterpretationQuestion 24 of 100
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.First-degree AV block
b.Second-degree AV block, Mobitz II
c.Third-degree AV block
d.Second-degree AV block, Mobitz I (Wenckebach)
Explanation
Mobitz I, also called Wenckebach, shows the PR interval getting progressively longer until one P wave is not conducted and a QRS is dropped, then the cycle starts over. First-degree block never drops a beat. Mobitz II drops beats while the conducted PR intervals stay constant, and third-degree block has P waves and QRS complexes that march independently.
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