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CARDIO & RESPIRATORY phase 1b > Electrocardiography and Rhythm Disorders > Flashcards

Electrocardiography and Rhythm Disorders Flashcards

1
Q

What can ECGs show?

A
  • the electrical activity of the heart
  • clinical abnormalities
  • structural abnormalities
  • perfusion abnormalities
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2
Q

What are the advantages of using an ECG?

A
  • cheap
  • easy
  • reproducible
  • quick
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3
Q

What is a vector?

A

a quantity with both a magnitude and a direction

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4
Q

What does the isoelectric line represent?

A

no net change in voltage (the vector is perpendicular to the lead)

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5
Q

What does the steepness of the line show?

A

the velocity of the action potential

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6
Q

What does the width of the wave represent?

A

the duration of the action potential

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7
Q

What does the p wave represent?

A

the electrical signal for atrial contraction given by the SA node

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8
Q

What does the QRS complex indicate?

A

The electrical signal that stimulates contraction of the ventricles (ventricular systole)

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9
Q

What does the T wave indicate?

A

The electrical signal that signifies relaxation of the ventricles

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10
Q

What part of the heart does the P wave represent?

A

the atria

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11
Q

what does the SA node do?

A

Contains auto-rhythmic myocytes that electrically signal for atrial depolarisation

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12
Q

What does the AV node do?

A
  • Slow signal conduction
  • Allows for ventricular filling
    -AVN depolarisation
  • Protective
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13
Q

What part of an ECG represents the action of the AVN?

A

the PR segment

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14
Q

Why is there no deflections shown during the conduction by the Bundle of His?

A

Rapid, Insulated conduction that is perpendicular to the direction of the lead (therefore doesn’t show on the trace)

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15
Q

What is responsible for Q?

A

Bundle branches cause septal depolarisation

- left side is slightly less insulated, therefore the signal escapes against Lead II direction.

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16
Q

What causes an R wave?

A

Purkinje fibres causing ventricular depolarisation

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17
Q

What causes an S wave?

A

Late depolarisation of Purkinje fibres of ventricle

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18
Q

What causes the T wave?

A

Ventricular repolarisation

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19
Q

What is the rule of Ls?

A

Lead I - Right Arm> Left Arm (one L)
Lead II - Right Arm> Left Leg (two Ls)
Lead III - Left Arm> Left Leg (three Ls)

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20
Q

What is the rule of reading ?

A

Drawn as a triangle, read from Left to Right, and then Top to Bottom

the first electrode of each bipolar pair you reach is the –ve electrode

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21
Q

where is V1 placed?

A
  • Right of sternum
  • 4th intercostal space
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22
Q

Where is V2 placed?

A
  • Left of the sternum
  • 4th intercostal space
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23
Q

Where is V3 placed?

A
  • Left
  • halfway between V2 and V4
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24
Q

Where is V4 placed?

A
  • Left mid-clavicular line
  • 5th intercostal space
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25
Q

Where is V5 placed ?

A
  • Left anterior axillary line
  • 5th intercostal space
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26
Q

Where is V6 placed?

A
  • Left mid axillary line

- 5th intercostal space

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27
Q

Can you shock during asystole?

A

No

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28
Q

What are the characteristics of sinus rhythm?

A
  • every P wave is followed by a QRS complex
  • regular rate (even R-R intervals)
  • normal HR (60-100bpm)
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29
Q

What causes a sinus arrhythmia and what are its characteristics?

A
  • stress
  • exercise
  • stimualtants
  • rate is irregular (variable R-R intervals)
  • R-R intervals vary with breathing cycle
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30
Q

What are the characteristics of atrial fibrillation?

A
  • oscillating baseline (atria contracting asynchronously)
  • turbulent blood flow increases clot risk
  • slow rate
  • irregularly irregular PR intervals
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31
Q

What are the characteristics of atrial flutter?

A
  • regular, saw tooth pattern in baseline
  • saw tooth is not always visible
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32
Q

What are the characteristics of a first degree heart block?

A
  • prolonged PR interval caused by slower AV conduction
  • regular rhythm
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33
Q

What are the characteristics of second degree heart block (Mobitz I/Wenckebach)?

A
  • gradual prolongation of the PR interval until a beat is skipped
  • most P waves are followed by QRS complexes, some are not
  • regularly irregular rhythm - diseased AV nodes
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34
Q

What are the characteristics of second degree heart block (Mobitz II)?

A
  • regular P waves, only
  • skipped QRS complex
  • regularly irregular rhythm
  • can rapidly deteriorate into 3rd degree heart block
35
Q

What are the characteristics of third degree (complete) heart block?

A
  • regular P waves, regular QRS complexs - BUT no relationship
  • no sinus rhythm
36
Q

when does something have a non-sinus rhythm?

A

when the electrical stimulation of the heart isn’t initiated by the SA node

37
Q

What are the characteristics of ventricular tachycardia?

A
  • P waves hidden - dissociated atrial rhythm
  • rate is regular and fast (100-200bpm)
  • shockable rhythm
  • high risk of deteriorating into fibrillation
38
Q

What are the characteristics of ventricular fibrillation?

A
  • HR is irregular and >250bpm
  • heart is unable to generate output
  • shockable rhythm
39
Q

What are the characteristics of an ST elevation?

A
  • visible P waves followed by a QRS complex (1:1)
  • regular rate and rhythm
  • ST segment is elevated >2mm above the isoelectric line
  • caused by infarction
40
Q

What are the characteristics of an ST depression?

A
  • visible P waves followed by a QRS complex (1:1)
  • regular rhythm and normal rate
  • depressed >2mm below the isoelectric line
  • caused by myocardial ischemia
41
Q

What can cause ST elevation?

A

infarction (tissue death due to hypoperfusion) - STEMI

42
Q

What causes Mobitz-1 type second degree heart block?

A

a diseased AV node

43
Q

What is first degree heart block indicative of?

A

benign, progressive disease of aging

44
Q

Where does atrial flutter tend to be seen?

A

leads II, III, and aVF

45
Q

What can be a complication associated with atrial fibrillation?

A

turbulent blood flow pattern increases the risk of clots

46
Q

What is the impact of atrial fibrillation on cardiac output?

A

minimal, as atria are not essential to the cardiac cycle

47
Q

What tends to cause sinus tachycardia?

A

often a physiological response, secondary to another factor

48
Q

What can cause sinus bradycardia?

A
  • can be normal/healthy
  • medication
  • vagal stimulation
49
Q

What are the steps of reading an ECG?

A
  • rate and rhythm
  • P wave and PR interval
  • QRS duration
  • QRS axis
  • ST segment
50
Q

What is every small box on an ECG worth (s)?

A

0.04 seconds

51
Q

What is every small box on an ECG worth (mV)?

A

0.1mV

52
Q

What are the lateral leads?

A

I, aVL, V5, V6

53
Q

What are the inferior leads?

A

II, III, aVF

54
Q

What are the septal leads?

A

V1, V2

55
Q

What are the anterior leads?

A

V3, V4

56
Q

What is the normal length of an R-R interval?

A

0.6-1.2 seconds

57
Q

What is the normal length of a P wave?

A

80ms

58
Q

What is the normal length of a P-R interval?

A

120-200ms

59
Q

What is the normal length of a QRS complex?

A

<120ms

60
Q

What is the normal length of a Q-T interval?

A

420ms

61
Q

What is the normal length of a T wave?

A

160ms

62
Q

How do you calculate cardiac axis?

A
  • calculate the net deflection of the QRS complex of II and aVL (parallel leads)
  • SoH CaH ToA to find the angle
  • 60 - angle found =
63
Q

What is the PR interval?

A

start of P wave to the start of the QRS complex

64
Q

When is a change in the PR interval problematic?

A

> 0.2 seconds (one big box)

65
Q

What is a prolonged QRS complex?

A

> 0.12seconds

66
Q

What is the relationship between the QT interval and heart rate?

A

as heart rate increases, QT interval shortens

67
Q

What are these?

A

Electrodes, connect to person

68
Q

What are these?

A

Cables, attach the person to the machine

69
Q

What are these?

A

Leads, represent electrical activity

70
Q

What do upward deflections represent?

A

Movement towards the positive electrode

71
Q

What do downward deflections represent?

A

Movement towards the negative electrode

72
Q

How are cardiac vectors represented?

A

by an arrow in the net direction of movement, whose size reflects the magnitude

73
Q

Which heart block is the most benign?

A
  • first degree
    -progressive disease of aging
74
Q

What do the 12 leads show?

A

The 12 views of the heart

75
Q

Which leads are on the coronal plane?

A

3 limb leads and 3 augumented vector leads

76
Q

Which leads are on the axial plane?

A

6 chest leads

77
Q

How many electrodes are needed for a 12 lead ECG?

A

10

78
Q

What do the lateral leads correspond to?

A

Left circumflex artery

79
Q

What do the inferior leads correspond with?

A

Right coronary artery

80
Q

What do the anterior and septal leads correspond with?

A

Left anterior descending artery

81
Q

How do you calculate the rate on an ECG?

A

300/number of large squares between R-R intervals

82
Q

How can the rhythm be described on an ECG?

A
  • sinus or non-sinus
  • regular, regularly irregular, irregularly irregular
83
Q

What is the cardiac axis?

A

The net effect of all generated action potentials

84
Q

What is a normal cardiac axis?

A

-30 to +90 degrees

CARDIO & RESPIRATORY phase 1b (14 decks)

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