CVS Practice Test

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Prepare for the CVS Test with tailored quizzes, featuring flashcards and multiple-choice questions with explanations. Set yourself up for success!

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In determining whether the QRS axis is normal or deviated, which leads should be examined?

Leads II and III
Leads I and II
Leads V5 and V6
Leads aVR and aVL

The correct answer is: Leads I and II

To determine whether the QRS axis is normal or deviated, examining leads I and II is crucial because these leads provide comprehensive information about the electrical activity of the heart along the frontal plane. Lead I measures the electrical activity from the right arm to the left arm, while Lead II measures the activity from the right arm to the left leg. A normal QRS axis is typically between -30 degrees and +90 degrees in the frontal plane, and analyzing these two leads gives an effective snapshot of where the heart is oriented electrically. If the QRS complex is predominantly positive in both leads, this supports a normal axis. In contrast, variations in the electrical orientation noted in these leads will indicate deviations of the axis, whether towards left or right. Leads V5 and V6 primarily evaluate the horizontal plane; lead aVR provides insight into right-sided heart activity but does not offer the same direct orientation regarding the frontal plane as leads I and II. Thus, they are less effective for determining axis deviation.