Rhythm Interpretation第 33 / 100 题
An otherwise normal sinus strip contains one early narrow beat with an inverted P wave right in front of it and a PR interval of 0.08 second. What is this beat?
a.Premature atrial contraction
b.Premature ventricular contraction
c.Premature junctional contraction
d.Sinus escape beat
解析
A premature junctional contraction comes from the AV junction, so the atria depolarize retrograde and produce an inverted P wave with a short PR of less than 0.12 second, while the QRS stays narrow. A premature atrial contraction has an upright though differently shaped P wave with a normal PR. A PVC is wide with no P wave, and an escape beat comes late, not early.
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