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Cardiovascular (Annie) > ECG > Flashcards

ECG Flashcards

1
Q

what is the ECG?

A

recording of potential changes, detected by electrodes positioned on the body surfaces
= allowing electrical activity of the heart to be monitored

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2
Q

how do potentials at the body surfaces arise?

A

arise from currents that flow when the membrane potential of myocardial tissue is changing (re-polarisation or depolarisation)

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3
Q

can all sizes of cardiac tissue generate sufficient current to be detected at body surface as potential changes?
Yes/no

A

NO.

- only large masses generate sufficient current to be detest at body surfaces

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4
Q

what ventricle has a notably larger mass?

A

left ventricle

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5
Q

what is an electrical dipole?

A

an electrical VECTOR, with components of magnitude and direction, that separates charges

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6
Q

what are the 2 components of the vector electrical dipole?

A

1) magnitude

2) direction

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7
Q

what is the magnitude determined by?

A

mass of cardiac muscle

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8
Q

what is the direction determined by?

A

overall activity of the heart

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9
Q

what is the ECG lead?

A

= the electrical picture obtained, the imaginary line, the lead axis, between two electrodes.
= NOT the wire that connects the electrodes to the recording device

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10
Q

In a lead, one electrode acts as the recording (positive) electrode.
What is the deflection on the ECG if the depolarisation is moving towards the recording electrode?

A

upwards deflection

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11
Q

what is the deflection on the ECG if the depolarisation is moving away from the recording electrode?

A

downwards deflection

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12
Q

what is an iso-potential?

A

there is no movement of current towers or away from the electrode, therefore. no deflection is seen

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13
Q

what are the 3 components of the 12 lead ECG?

A

1) 3 standard limb leads
2) 3 augmented voltage leads
3) 6 chest leads

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14
Q

what comprises the 3 standard limb leads?

what are these termed?

A

I
II
III

= Bipolar

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15
Q

what comprises the 3 augmented ted voltage leads?

what are these termed?

A 
aVR = right 
aVL = left 
aVF = foor

= Unipolar

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16
Q

what comprises the 6 chest leads?

what can these leads also be called?

A

V1 - V6

Pre-cordial leads

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17
Q

what leads provide a vertical picture of the heart?

A

Leads I, II & III

Leads aVR, aVL & aVF

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18
Q

what lead provides a horizontal picture of the heart?

A

Leads V1 - V6

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19
Q

describe where the movement occurs in Lead I.

A

From RA-ve

To LA+ve

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20
Q

describe where the movement occurs in Lead II.

A

From RA-ve

To LL+ve

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21
Q

describe where the movement occurs in Lead III

A

From LA-ve

To LL+ve

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22
Q

what tis the right legs role in an ECG?

A

its earthed

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23
Q

from what direction does Lead II see the heart?

A

from an INFERIOR direction

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24
Q

describe the direction of atrial depolarisation during the P wave on an ECG.

A

Spreads from SA node inferiorly to left

= moving TOWARDS recording electrode producing an upward deflection

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25
Q

what does the P wave duration normally reflect in an ECG?

A

the time for the depolarisation of atrial muscle to be complete

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26
Q

what is the normal duration for a P wave in an ECG?

A

0.120s

120ms

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27
Q

describe the direction of depolarisation during the Q wave on an ECG as seen via lead 2.

A
  • left to right depolarisation of the INTRA-VENTRICULAR SEPTUM
  • moving slightly away from recording electrode
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28
Q

describe the direction of depolarisation during the R wave on an ECG.

A

depolarisation of main ventricular mass moving TOWARDS the recording electrode.
the main free walls of the ventricles depolarise causing a tall, narrow wave.

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29
Q

describe the direction of depolarisation during the S wave on an ECG.

A

depolarisation of ventricles at THE BASE OF THE HEART moving away from the recording electrode.
= produces a small narrow wave

30
Q

describe the direction of depolarisation during the T wave one an ECG.

A

ventricular re-polarisation moving in a direction OPPOSITE to that of depolarisation accounts for usually observed upward deflection

31
Q

what does a T wave represent?

A

ventricular re-polarisation

32
Q

what is a Q wave.

A

downward (negative) deflection preceding an R wave

33
Q

what is a R wave.

A

a deflection upward (positive), irrespective or not it is proceeded by a Q wave

34
Q

what is an S wave.

A

a downward (negatiive) deflection following an R wave

35
Q

what does the QRS complex represent?

A

ventricular activation, or depolarisation.

36
Q

how long does QRS normally last?

A
  1. 1s

(100ms) or less

37
Q

where does the PR interval start and end?

A 
starts = P wave 
ends = start of the QRS complex
38
Q

what does the PR interval reflect?

A

it reflects the time for SA node impulse to reach the ventricles

39
Q

what is the PR interval normally?

A

0.12-0.2s

40
Q

what is the PR interval strongly influenced by?

A

by AV node delay

41
Q

where does the ST segment start & end?

A

From the end of QRS complex to the start of the T wave.

42
Q

describe the ST segment?

A

it is normally iso-electric

43
Q

where does the QT interval start & end?

A

from the start of QRS complex to the end of the T wave.

44
Q

what does the QT interval reflect?

A

reflects the time for ventricular depolarisation & re-polarisation

45
Q

what is the normal duration for the QT interval in makes & females?

A 
Males = 0.44s
Females = 0.46s
46
Q

what does prolongation of QT interval predispose to?

A

predisposes to disturbances of cardiac rhythm

47
Q

describe Goldberger’s method?

A

One +ve electrode (recording)
Two other linked as -ve
effectively positions the reference electrode in the centre of the heart

48
Q

describe aVR waves

A

RA (+) to LA & LF (-)

49
Q

describe aVL waves

A

LA (+) to RA & LF (-)

50
Q

describe aVF waves

A

LF (+) to RA & LA (-)

51
Q

what is the hex axial reference system?

A

six views of the heart in Toal

52
Q

what are Leads I and aVL leads called?

A

LATERAL leads

53
Q

what do lateral leads measure?

A

each has the recording electrode on the left arm and views heart from the left.

54
Q

what are leads II, III and aVF called?

A

INFERIOR leads

55
Q

what do inferior leads measure?

A

each has the recording o the left foot and views heart from an inferior direction

56
Q

what term describes the chest leads?

A

unipolar

57
Q

describe the view of the heart provided by the chest leads?

A

in the HORIZONTAL plane

58
Q

where do leads V1 and V2 come from and where do they look at?

A

Come from;
= the right
Looking at;
= the inter ventricular septum

59
Q

what do leads V3 and V4 look at?

A

they look at the anterior of the heart

60
Q

what do leads V5 and V6 look at?

A

they look at the lateral aspect (left ventricle) of the heart

61
Q

in V1, what is the first positive defection in the QRS complex?

A

an R wave

62
Q

in V1, after the first positive defection in the QRS complex, what is the negative deflection that immediately follows?

A

the S wave

63
Q

what happens to the R wave as you progress from V1-V6?

A

R wave = increases

64
Q

what happens to the S wave as you progress from V1-V6?

A

S wave = decreases

65
Q

what happens to the ventricles during the ST segment?

A

ventricles contract

= systole

66
Q

what happens to the ventricles during the TP segment?

A

ventricles relax

=diastole

67
Q

how do you calculate heart fate from an ECG?

A

300/number of large squares between bears

68
Q

what time does a large box represent?

A

0.2seconds

69
Q

what time does a small box represent?

A

0.4seconds

70
Q

what is the ECG rhythm strip?

A

prolonged recording of one lead, usually lead 2

= allows you to determined heart rate and cardiac rhythm

71
Q

what 3 reasons show the need for 12 leads?

A

1) determine axis of the heart in thorax
2) look for ST segments or T wave changes in relation to specific regions of the heart
= crucial for diagnosing ischaemic heart disease
3) look for voltage criteria changes
= crucial in diagnosing chamber hypertrophy

72
Q

what 3 heart disease have a normal resting ECG?

A 
1) myocardial infarction 
= heart attack 
2) intermittent rhythm disturbance 
3) stable angina 
= if suspected do exercise ECG, look for ST changes during/after exercise. 
= absent during rest

Cardiovascular (Annie) (36 decks)

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