Normal EKG

Question 1

What is the function of the SA node?

Answer 1

• Initial depolarization of the myocardium.
• Sets the heart rate at 60-100 bpm.

Question 2

What does the AV node do?

Answer 2

Delays the electrical signal, allowing the ventricles time to fill with blood, with an inherent rate of 40-60 bpm.

Question 3

What is the function of the Bundle of His?

Answer 3

Transmits impulses from the AV node to the ventricles.

Question 4

What are the Purkinje fibers responsible for?

Answer 4

Spread the impulse through the ventricles, causing them to contract.

Question 5

Conduction Principles

• Automaticity = ?
• Rhythmicity = ?
• Conductivity = ?

Answer 5

• Automaticity: The heart’s ability to contract on its own without external stimuli.
• Rhythmicity: The heart’s ability to contract in a regular, rhythmic manner.
• Conductivity: The heart’s ability to transmit impulses throughout the myocardium.

Question 6

What are the main components of the cardiac cycle?

Answer 6

• Starts at the end of systole
• Includes closing of semilunar valves
• Opening of mitral valves for ventricular filling.

Question 7

What information does a 12-lead ECG provide?

Answer 7

Rate, rhythm, impulse conduction, myocardial pathology, and physiologic status.

Question 8

How many electrodes are used in a 12-lead ECG?

Answer 8

10 electrodes.

Question 9

Name the 6 limb leads in a 12-lead ECG.

Answer 9

• Lead I
• Lead II
• Lead III
• aVR
• aVL
• aVF

Question 10

What is the ‘Rule of L’s’ in ECG?

Answer 10

• Lead I (Right to Left Arm)
• Lead II (Right Arm to Left Leg)
• Lead III (Left Arm to Left Leg)

Question 11

What does the QRS complex represent?

Answer 11

• Depolarization of the ventricles
• Initiation of ventricular systole
• 0.06-0.10 sec

Question 12

What is the significance of the ST segment?

Answer 12

• Represents early ventricular repolarization
• Abnormalities may indicate heart disease

Question 13

What does the T-wave represent?

Answer 13

• ventricular repolarization
• beginning ventricular filling
• 0.16 sec

Question 14

What is the normal duration of the PR interval?

Answer 14

• 0.12-0.20 seconds
• 3-5 small boxes

Question 15

What does the P-wave represent?

Answer 15

• Depolarization of the atria
• 0.08-0.11

Question 16

What does a normal sinus rhythm look like?

Answer 16

• P waves are upright and precede every QRS complex
• PR interval 0.12-0.20 seconds
• QRS complex is identical and 0.06-0.10 seconds
• HR 60-100 bpm

Question 17

Define

• sinus bradycardia = ?
• sinus tachycardia = ?

Answer 17

Sinus Bradycardia: A sinus rhythm with a heart rate of less than 60 bpm.

Sinus Tachycardia: A sinus rhythm with a heart rate of more than 100 bpm.

Question 18

Define sinus tachycardia.

Answer 18

A sinus rhythm with a heart rate of more than 100 bpm.

Question 19

What is sinus arrhythmia?

Answer 19

An irregular sinus rhythm, often associated with breathing cycles.

Question 20

What does a 5-lead ECG typically assess?

Answer 20

Heart rate and rhythm in clinical settings.

Question 21

How is heart rate calculated using the 1500 method?

Answer 21

1500 divided by the number of small boxes between two R-waves.

Question 22

How is heart rate calculated using the 6-second method?

Answer 22

• Count the number of R-waves in a 6-second strip and multiply by 10.

• Use if abnormal

Question 23

What does the PR segment represent?

Answer 23

Transmission of the electrical impulse from the atria to the ventricles.

Question 24

What is the normal duration of the QRS complex?

Answer 24

0.06-0.10 seconds.

Question 25

What does the R-R interval measure?

Answer 25

The regularity of the heart rate.

Question 26

What might cause an abnormal QRS complex?

Answer 26

Conditions like ventricular hypertrophy or conduction block.

Question 27

What is the role of the Purkinje fibers in the ECG?

Answer 27

They cause the ventricles to contract, represented by the QRS complex.

Question 28

What does the QT interval represent?

Answer 28

The total time for ventricular depolarization and repolarization.

Question 29

What does an elevated ST segment indicate?

Answer 29

Possible myocardial infarction (STEMI).

Question 30

What does the P-R interval indicate in terms of conduction?

Answer 30

The time it takes for the electrical impulse to travel from the SA node through the AV node.

Question 31

Why is the T-wave important?

Answer 31

It indicates ventricular repolarization, and abnormalities can indicate electrolyte imbalances or ischemia.

Question 32

What does sinus arrest mean?

Answer 32

A pause in the heart's activity when the SA node fails to initiate an impulse.

Question 33

How do you calculate the heart rate using the Box Counting Method?

Answer 33

Count the number of large boxes between two R-waves and divide 300 by this number.

Question 34

What is the significance of a biphasic P-wave?

Answer 34

It may indicate atrial enlargement.

Question 35

What is the 'sawtooth' pattern on an ECG indicative of?

Answer 35

Atrial flutter.

Question 36

What might a wide QRS complex suggest?

Answer 36

Ventricular conduction delays or bundle branch blocks.

Question 37

What is the significance of the P-R segment being isoelectric?

Answer 37

It indicates that the atria have depolarized and the impulse is traveling to the ventricles.

Question 38

What does a notched P-wave indicate?

Answer 38

Possible left atrial enlargement.

Question 39

How does the 6-second method differ for figuring out heart rhythm?

Answer 39

It’s the only method suitable for calculating heart rate in irregular rhythms.

Question 40

What is the normal duration of a T-wave?

Answer 40

Approximately 0.16 seconds.

Question 41

How can electrode misplacement affect an ECG reading?

Answer 41

It can lead to incorrect interpretation of heart rhythms and conditions.

Question 42

What does a normal T-wave look like?

Answer 42

Upright and same direction as the P-wave, with a duration of about 0.16 seconds.

Question 43

What is the purpose of a caliper in ECG analysis?

Answer 43

To measure the R-R interval and check for regularity of the rhythm.

Question 44

.

Answer 44

.

Question 45

What does the term 'sinus rhythm' imply?

Answer 45

A heart rhythm originating from the SA node.

Question 46

What are the characteristics of sinus tachycardia?

Answer 46

Normal P, PR, and QRS but with a heart rate over 100 bpm.

Question 47

What is the main feature of sinus bradycardia?

Answer 47

Normal P, PR, and QRS but with a heart rate under 60 bpm.