Rhythm InterpretationQuestion 14 of 100
An otherwise regular sinus strip contains one early beat with a P wave shaped differently from the others, followed by a normal narrow QRS and then a pause. What is the early beat?
a.Premature atrial contraction
b.Premature ventricular contraction
c.Premature junctional contraction
d.Escape beat
Explanation
A premature atrial contraction arrives early and comes from an irritable site in the atria, so its P wave looks different from the sinus P waves but the QRS remains narrow because conduction to the ventricles is normal. A premature ventricular contraction would be wide and bizarre with no P wave. A junctional premature beat has an inverted or absent P wave, and an escape beat arrives late rather than early.
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