Master Electrical Axis Determination in EKG Interpretation

Question 1

Which of the following axes is calculated based on the direction of the QRS complex in the frontal plane?

Accepted Answer

QRS axis

Answer

P axis

Answer

T axis

Answer

ST segment axis

Question 2

The P axis is determined based on the direction of the:

Accepted Answer

P wave in lead II

Answer

QRS complex in lead aVL

Answer

T wave in lead V1

Answer

ST segment in lead III

Question 3

Which of the following conditions can cause a leftward shift of the P axis?

Accepted Answer

Left atrial enlargement

Answer

Right atrial enlargement

Answer

Ventricular tachycardia

Answer

Pulmonary embolism

Question 4

The T axis typically aligns with the:

Accepted Answer

QRS axis

Answer

P axis

Answer

QT interval

Answer

PR interval

Question 5

An electrical axis within the range of -30° to +90° is considered:

Accepted Answer

Normal

Answer

Right axis deviation

Answer

Left axis deviation

Answer

Extreme axis deviation

Question 6

If the QRS complex is primarily positive in leads I and aVF, the electrical axis is most likely approximately:

Accepted Answer

+90 degrees

Answer

-90 degrees

Answer

-30 degrees

Answer

+180 degrees

Question 7

Which condition can cause right axis deviation?

Accepted Answer

Right ventricular hypertrophy

Answer

Pulmonary embolism

Answer

Left ventricular hypertrophy

Answer

Myocardial infarction

Question 8

What is a potential clinical implication of a wandering electrical axis?

Accepted Answer

Cardiac arrhythmias

Answer

Heart block

Answer

Always a normal finding

Answer

Not clinically relevant

Question 9

An electrical axis of +120 degrees in the transverse plane suggests:

Accepted Answer

Left anterior fascicular block

Answer

Right anterior fascicular block

Answer

Inferior axis

Answer

Superior axis

Question 10

What is the primary advantage of utilizing electrical axis in EKG interpretation?

Accepted Answer

Assessing the heart's overall electrical activity

Answer

Identifying arrhythmias

Answer

Detecting myocardial ischemia

Answer

Determining the patient's blood pressure

Question 11

Which instrument is commonly used to measure the electrical axis on an EKG?

Accepted Answer

Protractor

Answer

Compass

Answer

Calipers

Answer

Ruler

Question 12

An ECG shows a positive QRS complex in leads I and aVF. What is the most likely electrical axis location?

Accepted Answer

+90 degrees

Answer

0 degrees

Answer

-90 degrees

Answer

-180 degrees

Question 13

An ECG indicates an electrical axis of -15 degrees. Which diagnosis is most likely?

Accepted Answer

Left axis deviation

Answer

Normal sinus rhythm

Answer

Right axis deviation

Answer

Atrial fibrillation

Question 14

An ECG tracing shows an isoelectric QRS complex in a lead. What is its electrical axis?

Accepted Answer

0 degrees

Answer

180 degrees

Answer

90 degrees

Answer

45 degrees

Question 15

What is the clinical significance of a rightward shift in the electrical axis?

Accepted Answer

May indicate right ventricular hypertrophy

Answer

May indicate left ventricular strain

Answer

May be a normal variant

Answer

May indicate atrial flutter

Question 16

Explain the difference between the mean electrical axis and the dominant QRS vector.

Accepted Answer

Mean electrical axis represents the average direction of all QRS vectors, while dominant QRS vector represents the strongest QRS vector

Answer

Dominant QRS vector represents the average direction of all QRS vectors, while mean electrical axis represents the strongest QRS vector

Answer

They are essentially the same concept

Answer

Mean electrical axis is calculated using the Einthoven's Triangle method, while dominant QRS vector is calculated using the Hexaxial Reference System

Question 17

Which condition most commonly causes right axis deviation?

Accepted Answer

Right bundle branch block

Answer

Left anterior fascicular block

Answer

Left posterior fascicular block

Answer

Inferior wall myocardial infarction

Question 18

Which factor determines the electrical axis?

Accepted Answer

Direction of the mean QRS vector

Answer

Direction of the mean T wave vector

Answer

Direction of the mean P wave vector

Answer

Direction of the mean PR interval

Question 19

Which condition is most commonly associated with left axis deviation?

Accepted Answer

Left ventricular hypertrophy

Answer

Right ventricular hypertrophy

Answer

Atrial septal defect

Answer

Ventricular septal defect

Question 20

What is the primary clinical significance of determining the electrical axis in EKG analysis?

Accepted Answer

Providing information about cardiac chamber enlargement

Answer

Identifying cardiac rhythm disturbances

Answer

Indicating the presence of cardiac ischemia

Answer

Predicting the risk of cardiac events

Question 21

Which lead combination is typically used for electrical axis determination?

Accepted Answer

Lead I and lead III

Answer

Lead II and lead V1

Answer

Lead V5 and lead V6

Answer

Lead aVR and lead aVL

Question 22

An electrical axis of -170° is considered:

Accepted Answer

Extreme left axis deviation

Answer

Extreme right axis deviation

Answer

Wandering atrial pacemaker

Answer

Normal sinus rhythm

Question 23

A right axis deviation is most commonly associated with:

Accepted Answer

Patients with right ventricular hypertrophy

Answer

Healthy individuals

Answer

Patients with left ventricular hypertrophy

Answer

Patients with bundle branch block

Question 24

Statement: The electrical axis is always positive in healthy individuals.

Accepted Answer

False

Answer

True

Question 25

Which of the following leads is primarily used to determine the electrical axis?

Accepted Answer

Lead II

Answer

Lead I

Answer

Lead III

Answer

Lead V1

Question 26

In a typical EKG, within which quadrant does the electrical axis normally reside?

Accepted Answer

Quadrant I

Answer

Quadrant II

Answer

Quadrant III

Answer

Quadrant IV

Question 27

Which of the following factors does not influence the electrical axis?

Accepted Answer

Electrode placement

Answer

Heart's position in the chest

Answer

Heart chamber dimensions

Answer

Use of pacemakers

Question 28

In a left axis deviation, the primary vector is directed:

Accepted Answer

To the left

Answer

To the right

Answer

Superiorly

Answer

Inferiorly

Question 29

Ventricular hypertrophy is the most common cause of:

Accepted Answer

Right axis deviation

Answer

Pulmonary embolism

Answer

Atrial fibrillation

Answer

Hyperthyroidism

Question 30

To determine the electrical axis in an EKG, which leads should be analyzed?

Accepted Answer

Leads I, II, and III

Answer

Leads V1, V2, and V3

Answer

Leads V4, V5, and V6

Answer

Leads I, aVL, and aVR

Question 31

What is the significance of an abnormal electrical axis?

Accepted Answer

May indicate heart disease or structural abnormalities

Answer

Always signifies serious illness

Answer

Can be overlooked as it lacks clinical relevance

Answer

Only affects the interpretation of ST-segment changes

Question 32

In a right bundle branch block, the electrical axis typically shifts:

Accepted Answer

Rightward

Answer

Leftward

Answer

Superiorly

Answer

Inferiorly

Question 33

In an EKG showing a left axis deviation, what is the expected direction of the QRST vector?

Accepted Answer

Leftward and posteriorly

Answer

Leftward and anteriorly

Answer

Rightward and anteriorly

Answer

Rightward and posteriorly

Question 34

Define electrical axis.

Accepted Answer

The average direction of the electrical impulse's movement through the heart

Answer

The point where the QRS complex equals zero

Answer

The duration of the PR interval

Answer

The time required for an electrical impulse to travel from the SA node to the AV node

Question 35

Which component is NOT part of the frontal plane?

Accepted Answer

Lead aVR

Answer

Lead I

Answer

Lead II

Answer

Lead III

Question 36

What is a potential clinical implication of right axis deviation?

Accepted Answer

May indicate right ventricular hypertrophy

Answer

May indicate left ventricular hypertrophy

Answer

May indicate atrial fibrillation

Answer

May indicate sinus tachycardia

Question 37

Which medication can lead to right axis deviation?

Accepted Answer

Amiodarone

Answer

Digoxin

Answer

Propranolol

Answer

Verapamil

Question 38

Which is NOT a potential cause of electrical axis deviation?

Accepted Answer

Normal aging

Answer

Ventricular hypertrophy

Answer

Bundle branch blocks

Answer

Pacemaker placement

Question 39

In which condition would you expect to find a left axis deviation (LAD)?

Accepted Answer

Left ventricular hypertrophy

Answer

Right ventricular hypertrophy

Answer

Pulmonary embolism

Answer

Pericarditis

Question 40

Which medication has the potential to cause a left axis deviation?

Accepted Answer

Quinidine

Answer

Digoxin

Answer

Propranolol

Answer

Ibuprofen

Question 41

What is the electrical axis of a patient whose QRS complex is equiphasic in leads I and aVF?

Accepted Answer

0°

Answer

-90°

Answer

+90°

Answer

+180°

Question 42

Which condition is commonly associated with a wandering electrical axis?

Accepted Answer

Atrial fibrillation

Answer

Ventricular tachycardia

Answer

Myocardial infarction

Answer

Emphysema

Question 43

When the QRS complex is positive in lead I and lead III, the electrical axis is located in:

Accepted Answer

Quadrant I

Answer

Quadrant II

Answer

Quadrant III

Answer

Quadrant IV

Question 44

Which of the following axes is determined using the electrical potentials from leads I, II, and III?

Accepted Answer

Frontal axis

Answer

Longitudinal axis

Answer

Transverse axis

Answer

Vertical axis

Question 45

Which condition is a potential contributor to left axis deviation?

Accepted Answer

Left bundle branch block

Answer

Right bundle branch block

Answer

Myocardial infarction

Answer

Electrolyte imbalance

Question 46

What clinical implication is associated with an electrical axis greater than 120 degrees?

Accepted Answer

Right ventricular hypertrophy

Answer

Left ventricular hypertrophy

Answer

Bundle branch block

Answer

Pacemaker rhythm

Question 47

Identify the EKG pattern characteristic of a superior electrical axis.

Accepted Answer

Dominant R waves in leads I and aVL

Answer

Dominant R waves in leads V1 and V4

Answer

Dominant S waves in leads II and III

Answer

Dominant Q waves in leads aVR and V6

Question 48

How does an inferior electrical axis affect the QRS complex in lead III?

Accepted Answer

Negative QRS complex

Answer

Narrower QRS complex

Answer

Wider QRS complex

Answer

Positive QRS complex

Question 49

Identify a limitation of electrical axis determination.

Accepted Answer

Determining the axis can be challenging in certain circumstances

Answer

It does not provide specific information about cardiac chamber size

Answer

It is only useful for diagnosing arrhythmias

Answer

It is not reproducible between different individuals

Question 50

Which of the following is the normal electrical axis range in adults?

Accepted Answer

-30 to +110 degrees

Answer

-180 to +180 degrees

Answer

0 to +90 degrees

Answer

0 to +180 degrees

Question 51

Which of the following indicates left axis deviation?

Accepted Answer

Electrical axis below -30 degrees

Answer

Electrical axis between -30 and +110 degrees

Answer

Electrical axis above +110 degrees

Answer

Electrical axis below -180 degrees

Question 52

What is the typical electrical axis deviation seen in patients with left bundle branch block?

Accepted Answer

Left

Answer

Right

Answer

Superior

Answer

Inferior

Question 53

True or False: The electrical axis of the heart is identical to its anatomical axis.

Accepted Answer

False

Answer

True

Question 54

Which of the following changes in lead I can indicate a left axis deviation?

Accepted Answer

Negative QRS complex

Answer

Positive QRS complex

Answer

Increased QRS amplitude

Answer

Decreased QRS amplitude

Question 55

The electrical axis of the heart is defined as:

Accepted Answer

The direction of the mean QRS vector

Answer

The magnitude of the QRS complex

Answer

The duration of the QRS complex

Answer

The shape of the P wave

Question 56

In a normal electrocardiogram (ECG), the electrical axis is typically located in which quadrant?

Accepted Answer

I

Answer

II

Answer

III

Answer

IV

Question 57

A rightward shift of the electrical axis may be an indication of:

Accepted Answer

Right ventricular hypertrophy

Answer

Left ventricular hypertrophy

Answer

Atrial fibrillation

Answer

Pacemaker rhythm

Question 58

Which of the following is NOT a type of electrical axis deviation?

Accepted Answer

Superior axis deviation

Answer

Left axis deviation

Answer

Right axis deviation

Answer

Inferior axis deviation

Question 59

Which lead I deflection indicates the depolarization of the right atrium?

Accepted Answer

P wave

Answer

QRS complex

Answer

T wave

Answer

U wave

Question 60

In normal sinus rhythm, which axis determination method typically yields an axis between -30 and +90 degrees?

Accepted Answer

QRS axis

Answer

P axis

Answer

T axis

Answer

QT axis

Question 61

Which combination of leads is used to determine the frontal plane axis?

Accepted Answer

I and II

Answer

I and III

Answer

I and aVF

Answer

II and III

Question 62

Which of the following leads is NOT used to determine the electrical axis?

Accepted Answer

Lead aVR

Answer

Lead I

Answer

Lead II

Answer

Lead aVL

Question 63

Which of the following formulas is used to calculate the electrical axis using the limb leads?

Accepted Answer

Electrical Axis = (Lead I + Lead III) / 2

Answer

Electrical Axis = (Lead I - Lead III) / 2

Answer

Electrical Axis = (Lead II + Lead III) / 2

Answer

Electrical Axis = (Lead I + Lead II) / 2

Question 64

What is the clinical significance of determining the electrical axis?

Accepted Answer

It aids in diagnosing certain heart conditions, such as myocardial infarction.

Answer

It helps identify potential arrhythmias.

Answer

It is used to evaluate pacemaker function.

Answer

It is essential for proper medication dosing.