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Block 2 > Clin Lab: EKG > Flashcards

Clin Lab: EKG Flashcards

PowerPoints: EKG Cardiac physiology, EKG basics, EKG fields & vectors

1
Q

What is responsible for maintain a membrane potential at rest?

A

Na/K ATP pump

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2
Q

Where is there more Na+?

A

outside the cell

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3
Q

Where is there more K+?

A

inside the cell

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4
Q

Explain Na/K movement with the Na/K ATP pump.

A

3 Na+ in; 2 K+ out

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5
Q

How does the Na/K ATP pump create electrical signals.

A

pumping the Na+ & K+ sets up a potential difference on each side of the cell membrane

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6
Q

What are the phases of a cardiac action potential?

A

Depolarization
Repolarization
Refractory period
Contraction

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7
Q

Depolarization

A

Rapid depolarization b/c Na+ channels open & causes influx (gives us the rapid spike in AP)

Ca+ channel open & causes influx and K+ channels open & causes outflow (gives us the plateau in AP)

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8
Q

Repolarization

A

Ca+ channels close & additional K+ channels open

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9
Q

Refractory period

A

resetting of everything occurs.
Na/K pump moves Na+ back out & K+ back in

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10
Q

What is the reversal of membrane potential?

A

Depolarization

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11
Q

What makes a heart action potential to be longer compared to neurons?

A

influx of Ca++

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12
Q

Describe the physiology of cardiac muscle cells.

A

branched, make connections w/ other cells, laid down in layers, & go in different directions

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13
Q

Desmosomes

A

structural connections that act like Velcro

hold the cell membrane in place so the cell doesn’t pull apart from each other when the heart is contracting.

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14
Q

Gap junctions

A

function as tunnels that connect cytoplasms. This is how depolarization can spread from one cardiac cell to the next so quickly.

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15
Q

What is responsible for spontaneous depolarization??

A

pacemaker cells

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16
Q

Primary pacemaker?

A

SA node

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17
Q

How are pacemaker cells unique?

A

no nerve control
never really at a resting potential, there is always some Na+ trickling in

(This is why the heart keeps beating even if there is no connection to the brain.)

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18
Q

Why is the SA node the primary pacemaker?

A

it spontaneously depolarizes the fastest

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19
Q

What & how does the body control the rate of Na+ inflow?

A

The Nervous System (sympathetic & parasympathetic) influences the rate by changing the number of Na+ channels that open.

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20
Q

SA node location

A

upper right atrium

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21
Q

What separates the atria & ventricles?

A

a layer of non-conductive CT which is where the AV valves are embedded.

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22
Q

AV bundle divides to form…

A

left & right AV bundles

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23
Q

The left AV bundle divides into…

A

anterior & posterior fascicle

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24
Q

AV node location

A

floor of the right atrium

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25
Q

Describe an electrical field.

A

any time there is a separation of charges (dipole). Some cells have depolarized & some haven’t.

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26
Q

No electrical fields & no electrical signal is also known as

A

resting state

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27
Q

What does no electrical signal show on the EKG?

A

nothing

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28
Q

Describe visual depiction of a vector.

A

an arrow that points towards the positive side & a cross on the negative side

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29
Q

In which direction do electrical fields point?

A

always point towards the positive

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30
Q

Describe the electric vectors of the heart.

A

During atrial or ventricular depolarization there a lot of small electrical fields in all directions.
Electrical fields in a particular direction are summed together to create one overall vector which is what the EKG machine picks up.

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31
Q

What is another name for the overall electrical vector?

A

major prime electrical vector

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32
Q

Einthoven’s original electrode

A

Left arm, right arm, left leg

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33
Q

Why was the additional electrode added?

A

place on right leg to be a ground lead which detects background signal

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34
Q

What are examples of background pertaining to EKG?

A

breathing noises & muscle tone

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35
Q

Does the EKG machine pick up activity inside, outside, or in both places?

A

outside of the cell

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36
Q

EKG showing when the is no depolarization

A

straight line of the EKG tracing

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37
Q

What is the straight line on the EKG tracing called?

A

isoelectric baseline

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38
Q

What does the EKG tracing show if the overall vector points towards a positive electrode?

A

upward deflection

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39
Q

What does the EKG tracing show if the overall vector points away from a positive electrode?

A

downward deflection

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40
Q

What does the EKG tracing show if the overall vector is perpendicular to the positive electrode?

A

biphasic deflection

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41
Q

How many electrodes are used in a standard 12 lead EKG?

A

10

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42
Q

List the 10 electrodes

A

RA, LA, LL, RL (ground)
V1-V6

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43
Q

Location of leads RA & LA.

A

outwardly on shoulders (preferable on bone)

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44
Q

Location of V1 & V2

A

4 intercostal space on either side of the sternum

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45
Q

Location of V3

A

halfway b/t V2 & V4

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46
Q

Location of V4 - V6

A

along a horizontal line, wraps around the heart to under axillae

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47
Q

List the limb leads

A

I, II, III, aVR, aVL, aVF

48
Q

List the chest leads

A

V1-V6

49
Q

Explain bipolar leads.

A

One electrode is (+) & the other is (-) for any given lead
2 electrodes make up one lead

50
Q

Describe lead 1

A

left arm (+) right arm (-)

51
Q

Describe lead II

A

left leg (+) right arm (-)

52
Q

Describe lead 3

A

left leg (+) left leg (-)

53
Q

Describe augmented limb leads

A

they consist of a positive electrode which is then compared to a negative space; they are unipolar

54
Q

Location of the augmented leads

A

aVR - right arm (+)
aVL - left arm (+)
aVF - left foot (+)

55
Q

Which electrode is the most often used & why?

A

Lead II
the most anatomically aligned to the normal heart

56
Q

What do the limb leads show us?

A

the heart’s electrical activity in the frontal plane

57
Q

Describe Lead I view

A

horizontally across the top of the heart

58
Q

Describe Lead II view

A

upwards at the heart from the left hip

59
Q

Describe Lead III view

A

upwards at the heart from the right hip

60
Q

Describe aVF view.

A

straight up at the heart from the feet

61
Q

Describe aVR view

A

looking down at the heart from the right shoulder

62
Q

Describe aVL view

A

looking down at the heart from the left shoulder

63
Q

Describe the precordial (chest) leads.

A

six electrodes placed on the chest which correspond w/ 6 unipolar leads on the EKG; horizontal plane.

64
Q

What do leads V1 & V2 look at?

A

right ventricle

65
Q

What do leads V5 & V6 look at?

A

left ventricle

66
Q

What do leads V3 & V4 look at?

A

septum

67
Q

Dimensions of small boxes on EKG paper.

A

1mm x 1mm

68
Q

Dimension of big box on EKG paper.

A

5x5 small boxes. (5mm x 5mm)

69
Q

What’s does the horizontal axis on EKG paper represent?

A

time

70
Q

Time for 1 small box.

A

40 ms (0.04 sec)

71
Q

Time for 1 big box

A

200 ms (0.20 sec)

72
Q

Time for 5 big boxes

A

1000 ms (1sec)

73
Q

The amount of time on a standard 12 lead paper.

A

10 seconds

74
Q

What does the vertical axis on EKG paper represent?

A

Voltage (mV)

75
Q

Voltage for 1 small box

A

0.1 mV

76
Q

Voltage for 1 big box

A

0.5 mV

77
Q

Voltage for 2 big boxes

A

1 mV

78
Q

Most times, how do we clinically use the vertical axis on EKG paper.

A

too assess if a wave is too big or too small, not really actual numbers.

79
Q

Which lead is opposite of lead II?

A

aVR

80
Q

First deflection

A

P wave
- smaller amplitude than other waves.
- represents atrial depolarization
- first part is right atrium & second part if the left atrium

81
Q

Large deflection

A

QRS complex
- represents ventricular depolarization
- first negative wave = Q wave
- first positive wave = R wave
- next negative wave = S wave

82
Q

Do you see all ways on all leads?

A

No, it depends on the lead

83
Q

Last deflection

A

T wave
- ventricular repolarization
- larger signal than atria (but smaller height)
- spread out and more rounded

84
Q

Describe a segnment

A

a relatively flat (isoelectric) area b/t two deflections

85
Q

Describe an interval

A

encompasses at least 1 deflection (+) or (-) and 1 flat (isoelectric) segments

86
Q

How is the P wave created?

A

an impulse from the SA node

87
Q

Boundaries of the PR segment

A

end of the P wave to start of the QRS complex

88
Q

Describe the atria during the PR segment.

A

all atrial cells are depolarized

89
Q

Describe the impulse during the PR segment.

A

impulse is held by the AV node

90
Q

How long should be PR segment be?

A

<200ms (1 big box or 5 small boxes)

91
Q

Boundaries of the PR interval

A

start of the P wave to start of QRS complex

92
Q

PR interval represents

A

time it takes for the impulse to travel through the atria & the AV node

93
Q

Describe the impulse & result during the QRS complex

A

once the impulse is through the AV node, rapid depolarization occurs throughout the ventricles & this produces ventricular contraction.

94
Q

There are leads that normally don’t have Q waves, but if they do this could mean?

A

pathological issue like damage to the heart (new or old)

95
Q

Boundaries of the ST segment

A

flat area b/t the end of the QRS complex & the beginning of the T wave

96
Q

What two things should be the same height on the EKG?

A

PR & ST segments

97
Q

What is happening with the ventricles during the ST segment?

A

All ventricular cells have depolarized

98
Q

What is the J point?

A

point of inflection where the S wave ends & the ST segment begins

99
Q

How do we assess if the PR & ST segments are aligned?

A

the J point

100
Q

Changes to the ST segment can represent…

A

ischemia - assessed for heart attacks. (STEMI or NSTEMI)

101
Q

Describe what is happening w/ ions during the T wave.

A

K+ ions leaving the cell returning the cell interior to a negative charge

102
Q

Boundaries of the QT interval

A

beginning of the QRS complex to the end of the T wave

103
Q

QT interval is also known as

A

systole

104
Q

Which is long systole or diastole?

A

diastole

105
Q

Describe an isoelectric line

A

the flat segments b/t the P, QRS, & T waves

106
Q

What is happening on the EKG during isoelectric lines?

A

EKG is electrically silent

107
Q

Describe depolarization of the septum.

A

it depolarizes first & does this from left to right

108
Q

Second (+) wave after S wave

A

R’ wave

109
Q

Positive wave after T wave and before P wave

A

U wave

110
Q

Normal time for PR interval

A

120 - 200 ms (< 1 big box)

111
Q

Normal time for QRS complex

A

60 - 100 ms (< 3 small boxes)

112
Q

Gray zone time for QRS complex

A

100 - 120 ms

113
Q

Abnormal time for QRS complex

A

> 120ms (> 3 small boxes)

114
Q

Normal time for QT interval

A

360 - 440 ms

115
Q

Describe the measuring facts when it comes to the QT interval

A
  • varies by HR
  • QT corrected (QTc) accounts for this
116
Q

Normal time for QTc in men & women.

A

< 440ms in men
< 460ms in women

117
Q

Describe the two types of EKGs

A

Rhythm strip - continous from 1 or 2 leads. (mostly in the ED, assessing underlying rhythm)

12 lead - standardized printout from all 12 leads (some will print a rhythm strop at the bottom)

Block 2 (13 decks)

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