Question 1

What does the "a" represent in the unipolar limb leads?
A) augmentation
B) attenuation
C) alteration
D) abatement

Accepted Answer

The "a" in the unipolar limb leads (aVR, aVL, aVF) stands for "augmented" as they measure the electrical activity of the heart from a single limb electrode with the other two electrodes serving as a reference point.

Question 2

Of the precordial leads,which are considered to be the lateral leads?
A) V5 and V6
B) V1, V2, and V3
C) V4, V5, and V6
D) V3, V4, V5 and V6

Accepted Answer

The lateral leads are located on the left side of the heart and monitor the activity of the lateral wall of the left ventricle. V5 and V6 are positioned laterally on the chest, hence they are considered to be the lateral leads.

Question 3

When electrical impulses travel away from the positive electrode,what would be recorded on the ECG tracing?
A) negative deflection
B) positive deflection
C) straight line
D) equiphasic deflection

Accepted Answer

Electrical impulses traveling away from the positive electrode will result in a negative deflection on the ECG tracing, indicating that the electrical activity is traveling in the opposite direction of the electrode.

Question 4

On ECG paper operating at standard speed,what is the duration of the large squares?
A) 0.2 seconds
B) 2 seconds
C) 0.04 sec
D) 0.4 sec

Accepted Answer

The duration of the large squares on ECG paper, which operates at a standard speed of 25 mm/sec, is 0.2 seconds. Each large square is made up of 5 small squares, with each small square representing 0.04 seconds.

Question 5

What is the correct electrode placement for the modified chest lead?
A) positive electrode at V1, negative electrode on left arm or shoulder
B) positive electrode at V3, negative electrode on left arm or shoulder
C) positive electrode at V6, negative electrode on right shoulder or arm
D) positive electrode at V2, negative electrode on right shoulder or arm

Accepted Answer

In the modified chest lead, the positive electrode is placed at V1, and the negative electrode is placed on the left arm or shoulder.

Question 6

Which of the following are considered to be precordial leads?
I.Lead I,II,III
II.aVR,aVL,aVF
III.V1,V2,V3,V4,V5,V6
A) III only
B) I and II only
C) I only
D) I, II, and III

Accepted Answer

The precordial leads specifically refer to V1, V2, V3, V4, V5, and V6, which are placed on the chest around the heart to record the heart's electrical activity from different angles. Leads I, II, III, aVR, aVL, and aVF are limb leads, not precordial.

Question 7

Of the precordial leads,which are considered to be the anterior leads?
A) V1, V2, V3, and V4
B) V1, V2, and V3
C) V4, V5, and V6
D) V5 and V6

Accepted Answer

V1, V2, V3, and V4 are considered to be the anterior leads as they are placed over the front of the heart and provide information about the septal and anterior regions of the left ventricle.

Question 8

What is the name of imaginary equilateral triangle formed by the axes of the limb leads?
A) Einthoven's
B) Entwhistle's
C) Eiserman's
D) Entemann's

Accepted Answer

The imaginary equilateral triangle formed by the axes of the limb leads is called Einthoven's triangle. It is named after Willem Einthoven, a Dutch physician who invented the electrocardiogram in 1903.

Question 9

What is the term for two or more waveforms together on an ECG?
A) complex
B) interval
C) segment
D) deflection

Accepted Answer

A waveform on an ECG is commonly referred to as a complex, which represents the electrical activity of the heart during a specific phase of the cardiac cycle. Examples include the QRS complex, which represents ventricular depolarization, and the T wave, which represents ventricular repolarization.

The other options listed are also features of an ECG:
B) interval represents the time between two points on the ECG waveform, such as the PR interval or QT interval.
C) segment represents a portion of the baseline between two waveforms, such as the ST segment.
D) deflection represents the direction and size of a waveform, such as the positive or negative deflection of the P wave.

Question 10

On an ECG tracing,what is an isoelectric line called?
A) segment
B) complex
C) waveform
D) interval

Accepted Answer

An isoelectric line is a straight line on an ECG tracing with no upward or downward deflection that represents a baseline or zero voltage. This line is often referred to as a segment.

Question 11

Of the limb leads,which contributes the least amount of information for the 12 lead ECG interpretation?
A) aVR
B) aVF
C) aVL
D) Lead III

Accepted Answer

The answer of Of the limb leads,which contributes the least...

Question 12

Of the limb leads,which leads are considered to be the inferior leads?
A) Leads II, III, and aVF
B) Leads II, III, and aVR
C) Leads I, II, III and aVR
D) Leads I, II, III and aVF

Accepted Answer

The inferior leads are Leads II, III, and aVF. These leads look at the inferior surface of the heart, which includes the diaphragmatic surface and the right ventricle.

Question 13

Which leads monitor the electrical activity in the frontal plane of the heart?
I.Limb leads
II.Precordial leads
III.Modified Chest Lead
A) I only
B) II only
C) I and III only
D) I and II only

Accepted Answer

Limb leads (I, II, and III, aVR, aVL, and aVF) monitor the electrical activity in the frontal plane of the heart, while precordial leads (V1-V6) monitor the horizontal plane.

Question 14

What waveform is recorded on an ECG tracing when an electrical impulse travels perpendicular to the lead axis?
A) equiphasic
B) positive
C) negative
D) sawtooth

Accepted Answer

When an electrical impulse travels perpendicular to the lead axis on an ECG, the recorded waveform is equiphasic, meaning it has equal positive and negative components.

Question 15

Which limb leads are considered to be the left lateral leads?
A) I and aVL
B) II and aVL
C) III and aVL
D) Leads I, II, and avL

Accepted Answer

I and aVL are considered to be the left lateral leads because they view the heart from a left-sided perspective, with aVL specifically looking at the lateral wall of the left ventricle. The other options have at least one lead that is not considered a left lateral lead.

Question 16

How many electrodes are used in a 12 lead ECG?
A) 10 electrodes
B) 12 electrodes
C) 6 electrodes
D) 16 electrodes

Accepted Answer

A 12-lead ECG actually uses 10 electrodes placed on the patient's limbs and chest to record the electrical activity of the heart from 12 different perspectives, but not 12 electrodes as might be assumed from its name.

Question 17

What is the standard speed at which ECG systems run?
A) 25 mm/sec
B) 25 cm/sec
C) 2.5 mm/sec
D) 2.5 cm/sec

Accepted Answer

The standard speed at which ECG (Electrocardiogram) systems run is 25 mm/sec. This speed allows for a balance between detail in the tracing and the length of paper used.

Question 18

When electrical impulses travel toward the positive electrode,what waveform would be recorded on the ECG tracing?
A) positive deflection
B) negative deflection
C) straight line
D) equiphasic deflection

Accepted Answer

When the electrical impulses travel toward the positive electrode, the wave will cause a positive deflection in the ECG tracing.

Question 19

Which health care professionals commonly obtain the ECGs in many hopsitals across the USA?
A) CRTs and RRTs
B) MDs and DOs
C) MAs
D) MLTs

Accepted Answer

CRTs and RRTs are commonly responsible for obtaining ECGs in many hospitals across the USA.

Question 20

Which limb leads are unipolar leads?
A) aVR, aVL, and aVF
B) I, II, and III
C) IV, V, and VI
D) I, II, and aVF

Accepted Answer

Limb leads aVR, aVL, and aVF are unipolar leads because they each have one positive electrode and use a combination of the other two as a shared negative electrode. The other choices have bipolar leads - I, II, and III are referred to as standard limb leads, while IV, V, and VI are chest (or precordial) leads.

Quiz 13: The Standard 12 ECG System

What does the "a" represent in the unipolar limb leads?

Of the precordial leads,which are considered to be the lateral leads?

When electrical impulses travel away from the positive electrode,what would be recorded on the ECG tracing?

On ECG paper operating at standard speed,what is the duration of the large squares?

What is the correct electrode placement for the modified chest lead?

Which of the following are considered to be precordial leads? I.Lead I,II,III II.aVR,aVL,aVF III.V1,V2,V3,V4,V5,V6

Of the precordial leads,which are considered to be the anterior leads?

What is the name of imaginary equilateral triangle formed by the axes of the limb leads?

What is the term for two or more waveforms together on an ECG?

On an ECG tracing,what is an isoelectric line called?

Of the limb leads,which contributes the least amount of information for the 12 lead ECG interpretation?

Of the limb leads,which leads are considered to be the inferior leads?

Which leads monitor the electrical activity in the frontal plane of the heart? I.Limb leads II.Precordial leads III.Modified Chest Lead

What waveform is recorded on an ECG tracing when an electrical impulse travels perpendicular to the lead axis?

Which limb leads are considered to be the left lateral leads?

How many electrodes are used in a 12 lead ECG?

What is the standard speed at which ECG systems run?

When electrical impulses travel toward the positive electrode,what waveform would be recorded on the ECG tracing?

Which health care professionals commonly obtain the ECGs in many hopsitals across the USA?

Which limb leads are unipolar leads?