NCMA EKG and Cardiovascular Procedures

Question 1

How many electrodes are placed on the patient for a standard 12-lead EKG?

Accepted Answer

10 electrodes (4 limb + 6 precordial)

Answer

A 12-lead EKG uses 10 electrodes — 4 limb electrodes (RA, LA, RL, LL) and 6 precordial (chest) electrodes (V1–V6). These 10 electrodes mathematically generate 12 distinct views of the heart's electrical activity.

Question 2

Where is the V1 precordial electrode placed for a standard 12-lead EKG?

Accepted Answer

Fourth intercostal space, right sternal border

Answer

V1 is placed at the 4th intercostal space on the RIGHT sternal border. V2 mirrors it on the LEFT sternal border. Accurate placement requires locating the sternal angle (angle of Louis) and counting intercostal spaces.

Question 3

What does the P wave represent on an EKG tracing?

Accepted Answer

Atrial depolarization

Answer

The P wave represents atrial depolarization — the electrical activation spreading across the atria that triggers atrial contraction. It precedes the QRS complex in normal sinus rhythm.

Question 4

A patient's EKG shows a heart rate of 110 bpm with regular rhythm and normal P waves before each QRS. This rhythm is classified as:

Accepted Answer

Sinus tachycardia

Answer

Sinus tachycardia is defined as a regular rhythm originating in the SA node (normal P waves before each QRS, consistent PR interval) with a rate exceeding 100 bpm. At 110 bpm with the described characteristics, this is sinus tachycardia.

Question 5

What is the primary reason for skin preparation before placing EKG electrodes?

Accepted Answer

To reduce skin resistance and ensure good electrical contact, reducing artifact

Answer

Skin has natural oils, dead cells, and impedance (resistance) that interfere with EKG signal quality. Proper skin preparation (light abrasion, cleansing with alcohol or dry cloth) reduces this resistance and improves electrode contact, minimizing artifact.

NCMA - National Certified Medical Assistant Practice Test

NCMA - National Certified Medical Assistant Practice Test

NCMA EKG and Cardiovascular Procedures