ECG

Question 1

What is the SA node?

Answer 1

dominant pacemaker of the heart has an intrinsic rate of 60-100

Question 2

What is the AV node?

Answer 2

AV node- back up pacemaker and has a rate of 40-60

Question 3

What is the AV node?

Answer 3

AV node- back up pacemaker and has a rate of 40-60

Question 4

What does a p-wave on an ECG represent?

Answer 4

Atrial depolarisation

Question 5

What does the QRS complex on an ECG represent?

Answer 5

Ventricular depolarisation and atrial repolarisation

Question 6

What does the T-wave on an ECG represent?

Answer 6

Ventricular repolarisation

Question 7

What does the PR interval on an ECG represent?

Answer 7

Atrial depolarisation and the delay caused by the AV node to allow atria to contract

Question 8

What do the boxes on ECG paper represent?

Answer 8

One large box= 0.2s
One small box= 0.04s

Question 9

Where do the 6 chest leads go on a 12 lead ECG?

Answer 9

V1- 4th intercostal space right of the sternum
(septal view )
V2- 4th intercostal space left of the sternum
(septal view)
V3- 4th intercostal space below V” (anterior view)
V4- in the 5th intercostal space mid-clavicular line (anterior view)
V5- goes in between V4 and V6 (lateral view)
V6- goes in the 5th intercostal space mid-axillary line (lateral view)

Question 10

Where do leads I, II, and III (standard limb leads) go in an ECG?

Answer 10

Lead I- goes from the right arm to the left arm (lateral view)
Lead II- goes from the right arm to left leg (inferior view)
Lead III- goes from the left arm to left leg (inferior view)

Question 11

Where do leads aVF, aVR and aVL (augmented limb leads) go in an ECG?

Answer 11

aVR- goes to right arm -150 degrees (none)
aVF -goes to right leg 90 degrees (inferior)
aVL- goes to left arm -30 degrees (lateral)

Question 12

What is rule number one of a normal ECG?

Answer 12

PR interval should be between 0.12-0.2 seconds

Question 13

What is rule 2?

Answer 13

QRS complex should not exceed 0.12 seconds

Question 14

What is rule 3?

Answer 14

QRS should be upright in leads I and II

Question 15

What is rule 4?

Answer 15

QRS and T-wave have the same direction in limb leads

Question 16

What is rule 5?

Answer 16

All waves are negative in aVR

Question 17

What is rule 6?

Answer 17

R wave must grow from V1 to V4 and S wave must grow from V1-V3

Question 18

What is rule 7?

Answer 18

ST segment must be isoelectric apart from in V1 and V2 where it may be slightly elevated

Question 19

What is rule 8?

Answer 19

P waves should be upright in I, II and V2-V6

Question 20

What is rule 9?

Answer 20

There should be no Q waves in I II and V2-V6

Question 21

What is rule 10?

Answer 21

T waves must be upright in I II and V2-V6

Question 22

How do you calculate heart rate on an ECG?

Answer 22

300/number of squares between QRS complexes

Question 23

What would tall pointed T waves on an ECG indicate?

Answer 23

Right atrial enlargement (hypertrophy)

Question 24

What would bifid (m-shaped) P waves on an ECG suggest?

Answer 24

Left atrial enlargement (hypertrophy) implicated in mitral regurgitation and stenosis

Question 25

What does the lack of P waves on an ECG suggest?

Answer 25

Atrial fibrillation

Question 26

What do sawtooth p waves (fairly prominent but lots of) on an ECG suggest?

Answer 26

Atrial flutter

Question 27

What do chaotic P waves suggest?

Answer 27

Atrial fibrillation

Question 28

What does first degree heart block look like on an ECG?

Answer 28

A prolonged but consistent PR interval

Question 29

What does a second degree Mobitz type 1 heart block look like on an ECG?

Answer 29

Gradually increasing PR interval until a beat stop. Then the process starts again

Question 30

What does a second degree Mobitz type 2 heart block look like on an ECG?

Answer 30

Consistent p wave duration with loss of QRS every 3 or 4 waves

Question 31

What does a 3rd degree heart block look like on an ECG?

Answer 31

P waves and QRS complexes that have no association with each other, Need a junctional or ventricular pacemaker fitted

Question 32

What does a decreased PR interval suggest?

Answer 32

P waves that originate from somewhere else e.g., if someone has a small atria
Could also mean the atrial impulse is getting to the ventricle via a shortcut would show as delta waves

Question 33

What do delta waves (slurred QRS complex) on an ECG indicate?

Answer 33

Wolf-Parkinson white syndrome

Question 34

What does a QRS complex wider than 0.12s indicate on an ECG?

Answer 34

Could indicate a left or right bundle branch block. The impulse is getting to one ventricle faster than the other

Question 35

What is normal height of a QRS complex in the chest and limb leads?

Answer 35

<5mm limb leads and <10mm chest leads

Question 36

What do tall QRS complexes indicate?

Answer 36

A tall QTS complex can imply ventricular hypertrophy

Question 37

When is a ST elevation significant and what does it signify?

Answer 37

When it is greater than 1mm in limb leads or 2mm in chest leads above the baseline.
Signifies myocardial infarction

Question 38

When is a ST depression significant and what does it signify?

Answer 38

When it is more than 0.5mm below the baseline in 2 contagious leads.
Signifies myocardial ischaemia

Question 39

What 2 events are tall T waves associated with?

Answer 39

Hypokalaemia and a hyperacute STEMI

Question 40

When are inverted T-waves normal?

Answer 40

In leads V1 and III

Question 41

What conditions can inverted T waves be implicated in?

Answer 41

Ischaemia
Bundle branch block V4-V6 indicates LBBB and V1 to V3 indicates RBBB
LVH (in lateral leads)
Hypertrophic cardiomyopathy (widespread)

Question 42

What can a biphasic T wave indicate?

Answer 42

Hypokalaemia

Question 43

What can a flattened T wave indicate?

Answer 43

Electrolyte imbalance
Ischaemia