EKG AcquisitionQuestion 43 of 100
A 12-lead tracing shows an inverted P wave, inverted QRS, and inverted T wave in lead I, while the chest leads look normal. What is the most likely cause?
a.The right arm and left arm electrodes are reversed
b.The V1 and V2 electrodes are reversed
c.The right leg electrode is loose
d.The paper speed is set to 50 mm/sec
Explanation
Reversing the right and left arm electrodes flips the polarity of lead I, producing a global inversion in that lead while the chest leads, which do not depend on arm placement, remain normal. Reversing V1 and V2 distorts only those chest leads. A loose right leg (ground) electrode causes baseline wander or noise rather than inversion, and a doubled paper speed stretches the complexes without inverting them.
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