ECG's

Question 1

How many limb leads are there in an ECG?

Answer 1

3
Lead I
Lead II
Lead III

Question 2

How many augmented leads are there in ECG?

Answer 2

3

Question 3

Name the three augmented leads in ECG.

Answer 3

aVR, aVL and aVF

Question 4

How many chest leads are there in ECG?

Answer 4

6
V1-6

Question 5

What do standard limb leads look at?

Answer 5

Events in the vertical or frontal plane

Question 6

Where does standard limb lead one (SLL1) record?

Answer 6

Right arm to left leg

Question 7

Where does standard limb lead two (SLL2) record?

Answer 7

Left leg to right arm

Question 8

Where does standard limb lead three (SLL3) record?

Answer 8

Left arm to left leg

Question 9

Which events are transmitted well and show clearly on ECG?

Answer 9

Fast events- depolarisation and repolarisation of the AP

Question 10

Which events are transmitted poorly and don’t show up on ECG?

Answer 10

Slow events e.g. the plateau of the AP

Question 11

In the SLL2, what will a wave of depolarisation approaching the electrode in the left leg do?

Answer 11

Cause a a positive potential relative to the electrode in the right arm.

Question 12

In the SLL2, what will a wave of depolarisation going away from the electrode in the left leg cause?

Answer 12

A negative potential relative to the electrode in the right arm

Question 13

In the SLL2, what will wave of repolarisation approaching the electrode in the left leg cause?

Answer 13

A negative potential relative to the electrode in the right arm

Question 14

In the SLL2, what will a wave of repolarisation going away from the electrode in the left leg cause?

Answer 14

A positive potential relative to the electrode in the right arm.

Question 15

RECAP- what does the P wave represent?

Answer 15

Atrial depolarisation

Question 16

RECAP- what does the QRS complex represent?

Answer 16

Ventricular depolarisation

Question 17

RECAP- what does the T wave represent?

Answer 17

Ventricular repolarisation

Question 18

What is meant by the PR interval?

Answer 18

Measurement from the start of the P wave to the start of the QRS complex

Question 19

What does PR interval measure?

Answer 19

Time from atrial depolarisation to ventricular depolarisation

Question 20

How long is PR interval usually?

Answer 20

0.2 seconds

Question 21

What is the time taken for the QRS complex used to measure?

Answer 21

Time for the whole of the ventricle to depolarise

Question 22

What does the QT interval measure?

Answer 22

Time for ventricles to depolarise and repolarise

Question 23

What is the average QT interval?

Answer 23

0.42 s at 60 bpm but varies with heart rate

Question 24

Why can’t you see atrial repolarisation on SLL2 ECG?

Answer 24

Because atrial repolarisation coincides with ventricular depolarisation.

->Ventricular depolarisation involves much more tissue depolarising much faster so it swamps any signal from atrial repolarisation.

Question 25

Okay so what also occurs when ventricular depolarisation occurs?

Answer 25

Atrial repolarisation.

Question 26

What happens during depolarisation of the ventricle?

Answer 26

Different parts of the ventricle depolarise at different times and at different directions.

Question 27

Which part of the ventricle depolarises first?

Answer 27

Interventricular septum - from left to right

Question 28

Which part of the ventricle depolarises second?

Answer 28

Bulk of the ventricle- from the endocardial to the epicardial surface

Question 29

Which part of the ventricle depolarises third?

Answer 29

Upper part of the interventricular septum

Question 30

Is the action potential longer in endocardial or epicardial cells?

Answer 30

Endocardial cells

Question 31

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

Answer 31

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

Question 32

What extra information do the augmented limb leads give you?

Answer 32

By recording from one limb lead with respect to the other two combined, it gives you 3 other perspective on events in the heart

Question 33

How is aVR recorded?

Answer 33

Recorded from the right arm with respect to the left arm and the left leg.

Question 34

How is aVF recorded?

Answer 34

From the left leg relative to the right arm and the left arm.

Question 35

How is aVL recorded?

Answer 35

From the left arm relative to the right arm and the left leg.

Question 36

What do precordial chest leads do?

Answer 36

Measure electrical events in the heart but on the transverse plane.

Question 37

Compare limb leads and precordial chest leads.

Answer 37

Limb leads look at the spread of depolarisation (and repolarisation) from 6 angles in the frontal plane, and the precordial leads look at the same events from 6 angles in the transverse plane.

Question 38

Which standard limb line does the rhythm strip reading come from?

Answer 38

SLL2

Question 39

What speed does the paper for an ECG run at?

Answer 39

25 mm/s

Question 40

How can you check the paper is running at the right speed?

Answer 40

Look at the calibrating pulse It should be 0.2 seconds (the length of one big square).

Question 41

What can the rhythm strip be used to calculate?

Answer 41

Heart rate

Question 42

Describe the two ways you can measure heart rate from the rhythm strip.

Answer 42

Measure the RR interval and work out how many occur in 60 . OR Count the R waves in 30 large squares (= 6 s) and multiply by 10

Question 43

Define bradycardia

Answer 43

HR below 60 bpm

Question 44

Define tachycardia

Answer 44

HR above 100 bpm

Question 45

What other questions should you ask yourself when looking at an ECG rhythm strip?

Answer 45

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

Question 46

What does STEMI stand for?

Answer 46

ST segment elevation myocardial infarction

Question 47

What does NSTEMI stand for?

Answer 47

Non-ST segment elevation myocardial infarction

Question 48

What is a myocardial infarction?

Answer 48

A heart attack

Question 49

What may elevation of the ST segment mean?

Answer 49

Something is seriously wrong. Indication of how serious the MI was.

Question 50

Which is more serious- STEMI or NSTEMI?

Answer 50

STEMI

Question 51

Use this link for a quiz/revision on ECG :)

Answer 51

http://ajames131.wix.com/ecginterp

Question 52

Which leads of the ECG look at the heart in the frontal plane?

Answer 52

I, II, III, aVR, aVF, aVL

Question 53

Which leads of the ECG look at the heart in the horizontal plane?

Answer 53

V1-6