The PR interval viewed on a normal electrocardiogram represents:
a. atrial depolarization.
b. ventricular depolarization.
c. onset of atrial activation to onset of ven-tricular activity.
d. "electrical systole" of the ventricles.
ANS: C
The PR interval represents the onset of atrial activation to the onset of ventricular activity. The P wave represents atrial depolarization. The QRS complex represents ventricular depolarization. The QT interval represents "electrical systole" of the ventricles.
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