First look at ECG

Question 1

Standard limb leads look at event in what plane

Answer 1

Vertical/frontal

Question 2

SLL I

Answer 2

Left arm with respect to right arm

Question 3

SLL II

Answer 3

Left leg with respect to right arm

Question 4

SLL III

Answer 4

Left leg with respect to left arm

Question 5

Fast events

Answer 5

Depolarisation and repolarisation of action potential

Question 6

Are fast event transmitted

Answer 6

Yes

Question 7

Slow events

Answer 7

Plateau of the action potential

Question 8

Are slow events transmitted

Answer 8

No

Question 9

What causes an upward-going blip

Answer 9

A wave of approaching depolarisation

Question 10

What is SLL II actually recording

Answer 10

The difference in potential between the left leg and right arm

Question 11

PR interval

Answer 11

Time from atrial depolarisation to ventricular depolarisation (0.12-0.2s)

Question 12

QRS period

Answer 12

Time for the whole of the ventricle to depolarise (0.08s)

Question 13

QT interval

Answer 13

Time spent while ventricles are depolarised (0.42s)

Question 14

Why is atrial depolarisation not seen

Answer 14

Coincides with ventricular repolarisation, ventricular repolarisation swamps any signal from atrial repolarisation

Question 15

Q part of QRS complex

Answer 15

Interventicular septum depolarises from left to right

Question 16

R part of QRS complex

Answer 16

Bulk of the ventricle depolarises from the endocardial to epicardial surface

Question 17

S part of QRS complex

Answer 17

The upper part of the interventicular septum depolarises

Question 18

Why is the T wave positive-going

Answer 18

Action potential in endocardial cells longer than epicardial cells, wave of repolarisation runs in opposite direction to wave of depolarisation

Question 19

Why is R wave bigger in SLl II than SLL I and SLL III

Answer 19

Main vector of depolarisation is in line with the axis of recording from the left leg with respect to the right arm

Question 20

Height of SLL R wave from higher to lowest

Answer 20

SLL II, SLL III, SLL I

Question 21

What extra information do augmented limb leads give

Answer 21

3 other perspective on events in the heart

Question 22

Augmented limb leads

Answer 22

Recording from one limb lead with respect to the other two combined

Question 23

aVR and aVL waves are

Answer 23

Negative

Question 24

aVF waves are

Answer 24

Positive

Question 25

What extra information to precordial leads give

Answer 25

Look at same events but in the horizontal/transverse plane

Question 26

Where are precordial leads arranged

Answer 26

In front of the heart

Question 27

V1 - V6

Answer 27

Progression from negative to positive

Question 28

What timing should the paper rhythm strip run by

Answer 28

25mm/sec

Question 29

Calibrating pulse is

Answer 29

0.2sec = 1 large square (5mm)

Question 30

Normal heart rate

Answer 30

60-100bpm

Question 31

Bradycardia heart rate

Answer 31

<60bpm

Question 32

Tachycardia heart rate

Answer 32

> 100bpm

Question 33

What the rhythm strip tells you

Answer 33

Heart rate
If each QRS complex is preceded by a P-wave
If PR interval too short or long
If QRS complex too wide
If QT interval too long

Question 34

Too short PR interval

Answer 34

<0.12s

Question 35

Too long PR interval

Answer 35

> 0.2s

Question 36

Too wide QRS complex

Answer 36

> 0.12s

Question 37

Too long QT interval

Answer 37

> 0.42s (at 60bpm)

Question 38

STEMI

Answer 38

ST elevated myocardial infarction

Question 39

STEMI indicates

Answer 39

Something has gone seriously wrong

Question 40

NSTEMI

Answer 40

Non-ST elevated myocardial infarction

Question 41

How to measure heart rate from a rhythm strip

Answer 41

Count number of R waves over 30 large squares and multiply by 10