Basics In ECG I

Question 1

What is an ECG

Answer 1

It is a recording of the changing potentials of the electric field imparted by the heart

Question 2

What’s a fundamental part of a CVS assessment

Answer 2

ECG

Question 3

What are some examples of arrhythmias

Answer 3

Sinus rhythm of atrial fibrillation
Bradycardia
Tachycardia

Question 4

What are some examples of heart injury

Answer 4

Ischemia and infarction

Question 5

What are some structural disorders an ECG can detect

Answer 5

LVH

Question 6

What are some metabolic disorders an ECG can detect

Answer 6

K disorder

Question 7

What forms the ECG

Answer 7

The electrical changes associated with depolarization and repolarization

Question 8

Depolarisation towards positive electrode results in …………. deflection (upward or downward), away from electrode deflection …………… (upward, downward)

Answer 8

Upward, downward

Question 9

What does the size of deflection reflect

Answer 9

The volume of the depolarised muscle

Question 10

Mention the pacemakers of the heart

Answer 10

SA Node (dominant pacemaker with an intrinsic rate of 60 - 100 beats/minute)
AV node
Ventricular cells

Question 11

What are the two back up pacemakers of the heart

Answer 11

AV node
Ventricular cells

Question 12

What is the rate of firing of the AV node

Answer 12

40-60 bpm

Question 13

What is the firing rate of the ventricular cells

Answer 13

20 - 45 bpm

Question 14

What node initiates atrial depolarization

Answer 14

SA node

Question 15

What is the natural pacemaker of the heart

Answer 15

SA node

Question 16

Which conduction system of the heart propagates impulses to the ventricles

Answer 16

AV node

Question 17

What are the conducting tissues of ventricles

Answer 17

His-Purkinje system

Question 18

What causes the P wave

Answer 18

Right and left atrial activation

Question 19

What activation causes the initial septal Q wave

Answer 19

Septal activation

Question 20

What causes the inscription of the whole QRS complex

Answer 20

Left ventricular free wall activation

Question 21

What causes the His-Purkinje U wave

Answer 21

Late ventricular repolarization

Question 22

Where is V1 placed

Answer 22

4th ICS - right of the sternum

Question 23

Where is V2 placed

Answer 23

4th ICS - left of the sternum

Question 24

Where is V4 placed

Answer 24

Left midelavicular line in the 5th intercostal space

Question 25

Where is V3 placed

Answer 25

Halfway between V2 and V4.

Question 26

Where is V5 placed

Answer 26

5th ICS - left anterior axillary line

Question 27

Where is V6 placed

Answer 27

5th ICS - left mid-axillary line

Question 28

What is another name for the chest leads (V1-V6)

Answer 28

Anterior leads

Question 29

In what plane do chest leads view the heart

Answer 29

Horizontal plane

Question 30

A standard 12-lead placement has how many electrodes

Answer 30

10 electrodes

Question 31

List the limb leads

Answer 31

I, II, III aVL, aVF, aVR

Question 32

In what plane do limb leads view the heart

Answer 32

Vertical plane

Question 33

Which leads view the heart from the inferior surface

Answer 33

II, III, aVF

Question 34

Which leads view the heart from the anterior surface

Answer 34

V1-V6

Question 35

Which leads view the heart from the lateral surface

Answer 35

I, aVL, V5-V6

Question 36

What is the paper speed of an ECG

Answer 36

25 mm/s

Question 37

What is the distance of 1 large square of an ECG

Answer 37

5 mm = 0.2 s

Question 38

What is the distance of 1 small square of an ECG

Answer 38

1mm = 0.04 s

Question 39

How many small squares make a large square in an ECG

Answer 39

5

Question 40

Electrical aspects in an ECG is measured in what unit

Answer 40

Millivolts

Question 41

Amplitude 1mV moves stylus ….. cm vertically …… mV = 1mm = 1 small square

Answer 41

1, 0.1

Question 42

The amplitude of the waveform of an ECG is influenced by

Answer 42

Myocardial mass Thickness of intervening tissue Distance between electrode and myocardium Net vector of depolarization

Question 43

What could low amplitude of an ECG be due to

Answer 43

Obesity COPD Pericardial fluid

Question 44

A high amplitude in an ECG could be due to

Answer 44

Thin patient LVH

Question 45

Why is the deflection of the p wave small

Answer 45

Because of the little muscle mass of the atrium

Question 46

P wave is upright in what leads

Answer 46

Leads I and II

Question 47

A negative p wave in lead I could be because of

Answer 47

An incorrect lead placement Dextrocardia Ectopic atrial foci

Question 48

What is the PR interval

Answer 48

PR interval is the time between the onset of atrial depolarisation and the onset of ventricular depolarization

Question 49

PR Interval is constant True or false

Answer 49

True

Question 50

What is the normal duration of the PR interval

Answer 50

0.12-0.2 seconds