ECG

Question 1

What waves are seen on an ECG?

Answer 1

P QRS T

Question 2

What is the complex seen on an ECG?

Answer 2

QRS complex

Question 3

Why cant you see atrial repolarisation on an ECG?

Answer 3

Atrial repolarisation happens at the same time as ventricular depolarisation. Ventricular depolarisation involves much more tissue depolarising much faster so it swamps any signal from atrial repolarisation

Question 4

What happens at the Q of the QRS complex?

Answer 4

The interventricular septum depolarises from L to R

Question 5

What happens at the R of the QRS complex?

Answer 5

The bulk of the ventricle depolarises from the endocardial to the epicardial surface

Question 6

What happens at the S of the QRS complex?

Answer 6

Upper part of the interventricular septum depolarises

Question 7

What is the left leg in relation to?

Answer 7

Right arm

Question 8

Which direction does a wave of repolarisation go in?

Answer 8

AWAY from the electrode

Question 9

What direction does a wave of depolarisation go in?

Answer 9

TOWARDS the electrode

Question 10

Why is the R wave bigger in the SLL II than in the SLL I or SLL III?

Answer 10

Because the main vector of depolarisation is in line with the axis of recording from t he left leg with the respect to the right arm

Question 11

What is the P wave caused by?

Answer 11

Atrial depolarisation

Question 12

What is the QRS complex caused by?

Answer 12

Ventricular depolarisation

Question 13

What is the T wave caused by?

Answer 13

Ventricular repolarisation

Question 14

Why is the T wave positive?

Answer 14

The AP is longer in the endocardial cells than in the epicardial cells, so the wave of repolarisation runs in the opposite direction to the wave of depolarisation i.e. a wave of repolarisation moving away from the recording electrode produces another positive going blip

Question 15

What is the PR interval?

Answer 15

Time from atrial depolarisation to ventricular depolarisation

Question 16

What is the PR interval mainly due to?

Answer 16

Transmission through the AV node

Question 17

What is the QRS interval?

Answer 17

Time for the whole of the ventricle to depolarise

Question 18

Normal time of QRS interval

Answer 18

0.08 seconds

Question 19

What is the QT interval?

Answer 19

Time spent while the ventricles are depolarised

Question 20

What does the QT interval vary with?

Answer 20

HR

Question 21

Normal QT interval

Answer 21

0.42 seconds at 60 bpm

Question 22

What does a wave of depolarisation cause on an ECG?

Answer 22

Upward going blip

Question 23

Are fast events or slow events transmitted better?

Answer 23

Fast

Question 24

How to work out the HR from an ECG?

Answer 24

1. Measure R-R interval and work out how many in 60 seconds

2. Count how many R waves in 30 large squares (6 seconds) and multiple by 10

Question 25

Normal HR

Answer 25

60 - 100

Question 26

Name for < 60 bpm

Answer 26

Bradycardia

Question 27

Name for > 100 bpm

Answer 27

Tachycardia

Question 28

What else would you look at on an ECG?

Answer 28

HR Is each QRS complex preceded by a P wave? Is the PR interval too short (<0.12 sec) or too long (>0.2s) Is the QRS complex too wide (>0.12 sec) Is the QT interval too long (>0.42 s at 60bpm)?

Question 29

What does STEMI stand for?

Answer 29

ST elevated myocardial infarction

Question 30

What does NSTEMI stand for?

Answer 30

Non elevated myocardial infarction

Question 31

Which of STEMI or NSTEMI is worse?

Answer 31

STEMI

Question 32

What are the limb leads?

Answer 32

``` aVR aVF aVL SLL III SLL II SLL I ```

Question 33

Does AVF give a positive or a negative blip?

Answer 33

Positive

Question 34

Does AVR give a positive or a negative blip?

Answer 34

Negative

Question 35

Which precordium leads flip over?

Answer 35

V3/V4

Question 36

What plane do the limb leads look at?

Answer 36

Frontal plane

Question 37

What plane do the precordial leads look at?

Answer 37

Transverse plane

Question 38

What is a downward QR wave?

Answer 38

1st deflection

Question 39

What is a downward sR wave?

Answer 39

Subsequent deflection

Question 40

What does more voltage on the ECG indicate?

Answer 40

The more the muscle

Question 41

Max QRS width

Answer 41

3 little boxes

Question 42

What interval is very difficult to determine on the ECG due to all of the influencing variables?

Answer 42

QT interval

Question 43

What does prolonged P-R interval indicate?`

Answer 43

1st degree heart block

Question 44

Which Mobitz type of type II heart block is more pathological?

Answer 44

Mobitz type II

Question 45

What determines the atrial rate?

Answer 45

Between the P waves

Question 46

Causes of atrial dissociation

Answer 46

Complete heart block VT Pacemaker

Question 47

Does VT have to be >100bpm?

Answer 47

No, can be whatever speed it determines

Question 48

What type of BBB is always abnormal?

Answer 48

LBBB

Question 49

Signs on ECG of LBBB

Answer 49

V1 downward | V6 upright and notched

Question 50

Is RBBB always abnormal?

Answer 50

Can be a variant of normal

Question 51

Signs on ECG of RBBB

Answer 51

V1 smaller R waves and larger R prime | V6 slurred S wave

Question 52

How much of the myocardium does the left main stem artery cover?

Answer 52

2/3rds

Question 53

Causes of ST depression

Answer 53

Occlusion Severe hypotension Severe anaemia

Question 54

Why does troponin rise and fall in ischaemia?

Answer 54

Due to the dynamic features and nature of ischaemia

Question 55

Is P : QRS relationship is 1;1, what does this mean?

Answer 55

Sinus rhythm

Question 56

What wall of the heart is not looked at on the ECG? What can be looked at and where to try and identify this?

Answer 56

Posterior wall | Can look like ST depression on the anterior leads

Question 57

What artery supplies the sinus node?

Answer 57

Right coronary artery

Question 58

VF vs VT on ECG

Answer 58

VF - big amplitude, not same shape or frequency | VT - same waveform

Question 59

Does adenosine treat atrial tachycardia and why?

Answer 59

No - as does not needing the AV node

Question 60

What is used to treat SVT?

Answer 60

Cardioversion

Question 61

What kind of treatment is SVT?

Answer 61

An umbrella term

Question 62

Examples of Cardioversion

Answer 62

Valsalva Carotid sinus massage Adenosine

Question 63

Features of adenosine

Answer 63

Blocks AV node Half life 10 seconds Patients feel like they will die Cannulas placed as proximal as possible

Question 64

What is given after adenosine?

Answer 64

Saline

Question 65

Treatment of VT

Answer 65

Anaesthetist put patient to sleep - then Defibrillator If comes back - amiodarone

Question 66

What are little bumps on ECG usually? What do they usually confirm?

Answer 66

P waves | Confirms VT due to more ventricular activity

Question 67

Is there atrial activity in AF?

Answer 67

Yes, but all fluttered/fibrillating

Question 68

What do irregular QRS complexes represent?

Answer 68

AV nodal function in AF