NCMA EKG/ECG Lead Placement and Artifacts 2

Question 1

Where is the V4 precordial lead electrode placed?

Accepted Answer

5th intercostal space at the midclavicular line

Answer

V4 is placed at the 5th intercostal space in the midclavicular line (directly below the midpoint of the clavicle on the left side), which overlies the apex of the heart.

Question 2

What type of artifact on an ECG tracing is caused by patient movement or shivering?

Accepted Answer

Somatic muscle artifact (wandering or irregular baseline spikes)

Answer

Somatic (skeletal muscle) artifact appears as irregular, high-frequency spikes or a fuzzy, irregular baseline caused by involuntary or voluntary patient movement, shivering, or tremors.

Question 3

In a standard 12-lead ECG, how many limb leads are there?

Accepted Answer

6 (I, II, III, aVR, aVL, aVF)

Answer

There are 6 limb leads in the standard 12-lead ECG: three bipolar limb leads (I, II, III) and three augmented unipolar limb leads (aVR, aVL, aVF), with the remaining 6 being precordial (chest) leads.

Question 4

A medical assistant notes that the ECG baseline drifts slowly up and down in a wave-like pattern. What is the MOST likely cause?

Accepted Answer

Wandering baseline caused by poor electrode contact or patient breathing

Answer

Wandering baseline (also called baseline drift) appears as a slow, undulating movement of the isoelectric line, most commonly caused by inadequate skin preparation, poor electrode contact, or respiratory movement of chest electrodes.

Question 5

Which lead records electrical activity from a viewpoint directly at the bottom (inferior) surface of the heart?

Accepted Answer

aVF

Answer

aVF (augmented vector foot) has its positive electrode at the left leg, recording electrical activity as seen from directly below the heart, making it the primary inferior lead along with II and III.

NCMA - National Certified Medical Assistant Practice Test

NCMA - National Certified Medical Assistant Practice Test

NCMA EKG/ECG Lead Placement and Artifacts 2