ECG Flashcards

1
Q

What does a lead do?

A

Measures difference in potential at two points

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2
Q

Where does lead I go?

A

RA -ve to LA +ve

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3
Q

Where does lead II go?

A

RA -ve to LL +ve

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4
Q

Where does lead III go?

A

LA -ve to LL +ve

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5
Q

What does depolarisation towards the electrode cause?

A

Upward deflection in the ECG

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6
Q

What does depolarisation away from the electrode cause?

A

Downward deflection in the ECG

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7
Q

Which limb leads are bipolar?

A

Standard

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8
Q

Which limb leads are unipolar?

A

Augmented

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9
Q

What is the polarity of the augmented limb leads?

A

One positive electrode with the two others linked as negative

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10
Q

What is important to remember about aVR?

A

It is always inverted

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11
Q

Which plane do the chest leads work in?

A

Axial

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12
Q

How many electrodes are in a 12 lead ECG?

A

9

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13
Q

What does the ST segment correspond to?

A

Systole- ventricles contract

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14
Q

What does the TP segment correspond to?

A

Diastole- ventricles relax

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15
Q

What would be the next test to do in suspected intermittent rhythm disturbance?

A

Ambulatory ECG for 12 hours or 7 days

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16
Q

What would be the next test to do for stable angina?

A

Exercise ECG

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17
Q

Where should V1 be placed?

A

4th IC space, right sternal angle

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18
Q

Where should V2 be placed?

A

4th IC space, left sternal angle

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19
Q

Where should V3 be placed?

A

Halfway between V2 and V4

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20
Q

Where should V4 be placed?

A

Apex beat- 5th intercostal space midclavicular line

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21
Q

Where should V5 be placed?

A

Anterior axillary line

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22
Q

Where should V6 be placed?

A

Mid axillary line

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23
Q

How long does one large box correspond to?

A

0.2 secs

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24
Q

How long does one small box correspond to?

A

0.04 secs

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25
Q

What does the p wave represent?

A

Atrial depolarisation

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26
Q

What does the PR interval represent?

A

AV nodal delay

27
Q

What does the QRS complex represent?

A

Ventricular depolarisation

28
Q

What does the t wave represent?

A

Ventricular repolarisation

29
Q

What does the QT segment correspond to?

A

Depolarisation and repolarisation of the ventricles

30
Q

How long should the QT segment last?

A

0.36-0.44 secs

31
Q

How long should the p wave last?

A

0.08-0.1 secs

32
Q

How long should the PR interval be?

A

0.12-0.1 secs

33
Q

How long should the QRS complex last?

A

<0.1 secs

34
Q

How do you calculate the heart rate with a regular rhythm?

A

300/no of large squares between beats

35
Q

How do you calculate the heart rate with an irregular rhythm?

A

The number of QRS complexes in 30 large squares and multiply by 10

36
Q

What is step 1 of analysing an ECG?

A

Verify patient name and DOB

37
Q

What is step 2 of analysing an ECG?

A

Check date and time ECG was taken

38
Q

What is step 3 of analysing an ECG?

A

Check the calibration of the ECG paper

39
Q

What is step 4 of analysing an ECG?

A

Determine the axis

40
Q

What 7 things are involved in analysing the rhythm of an ECG?

A
Is electrical activity present?
Is the rhythm regular or not?
What is the heart rate?
Are p waves present
What is the PR interval? (normally 3-5 small squares)
Is each p wave followed by a QRS?
Is the QRS duration normal?
41
Q

What is step 6 of analysing an ECG?

A

Look at individual leads for voltage criteria changes and ST/t wave changes

42
Q

What suggests a normal ECG axis?

A

Complexes in lead I and II which are both positive

43
Q

What suggests left axis deviation?

A

-30 to -90 degrees

44
Q

What suggests right axis deviation?

A

+90 to +180 degrees

45
Q

What can cause left axis deviation?

A

LVH, inferior MI, VT from LV focus, WPW sometimes

46
Q

What can cause right axis deviation?

A

RVH, anterolateral MI, some WPW, PE

47
Q

What lead changes suggest an inferior MI?

A

II, III, aVF

48
Q

What lead changes suggest an anteroseptal MI?

A

V1-4

49
Q

What lead changes suggest an anterolateral MI?

A

V4-6, aVL

50
Q

What lead changes suggest a posterior MI?

A

tall R and and ST depression in V1-2

51
Q

What artery is involved in an inferior MI?

A

Right coronary

52
Q

Which artery is involved in an anteroseptal MI?

A

Left anterior descending

53
Q

Which artery is involved in a posterior MI?

A

Circumflex

54
Q

What can cause ST depression and inverted T waves in V5-6?

A

Digoxin effect

55
Q

What can cause tall, tented T waves, widened QRS and absent p waves?

A

Hyperkalaemia

56
Q

What can cause small T waves and prominent U waves?

A

Hypokalaemia

57
Q

What can cause a short QT interval?

A

Hypercalcaemia

58
Q

What can cause a long QT interval and small T waves?

A

Hypocalcaemia

59
Q

What do both types of bundle branch block cause?

A

Delayed conduction and hence prolonged QRS

60
Q

What can be seen on an ECG of right bundle branch block?

A

Inverted T waves in V1-3/4 and a deep wide S wave in V6

61
Q

What can be seen on an ECG of left bundle branch block?

A

M pattern in V5, inverted T waves in I, aVL and V5-6

62
Q

What are causes of right bundle branch block?

A

Isolated, PE, cor pulmonale

63
Q

What can cause left bundle branch block?

A

IHD, hypertension, cardiomyopathy, idiopathic fibrosis