EKGs Flashcards

1
Q

Is depolarization a process or a state?

A

Process

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2
Q

What is an EKG electrode detecting?

A

The flow of current

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3
Q

True or false: an EKG electrode will not show anything, unless there is a change in the membrane potential/ a flow of current

A

True

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4
Q

Positive charges moving toward an electrode produces what change on the EKG (rise above isoelectric line or drop below)?

A

Rises above

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5
Q

What is the P wave a result of?

A

Atrial myocyte depolarization

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6
Q

Where does depolarization begin for each heart beat?

A

In the SA node

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7
Q

Which wave on an EKG recording represents the SA node depolarizing?

A

There is none–too small to detect

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8
Q

What does the Q wave represent (if present)?

A

Septal depolarization

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9
Q

What is the first downward deflection of an EKG recording after the P wave? Is it alway present?

A

Q wave, not always there

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10
Q

What is the first upward deflection of an EKG recording after the P wave? Is it alway present?

A

R wave, should always be there

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11
Q

What is the first downward deflection of an EKG recording after the R wave? Is it alway present?

A

S wave, may be present

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12
Q

What does the R wave represent?

A

Ventricular muscle depolarization

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13
Q

What does the T wave represent?

A

Repolarization of the Ventricles

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14
Q

Which part of the EKG recording represents atrial repolarization?

A

There is none–hidden in the R wave

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15
Q

What is occurring in the atrial muscles between the P wave and the Q wave?

A

Ca influx into the atrial myocytes, maintaining the depolarization

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16
Q

What is happening to the AP between the P wave and the Q wave?

A

Going through the Purkinje fibers

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17
Q

What does the S wave represent?

A

Ventricular muscle depolarization away from the electrode

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18
Q

What does the ST segment represent relative to the ventricular myocytes?

A

Plateau of the AP d/t Ca influx

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19
Q

What is the chart speed of EKG paper?

A

25 mm/min

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20
Q

10 mm on the EKG paper corresponds to what mV?

A

1 mV

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21
Q

5 small boxes on EKG paper represent how many seconds?

A

0.2 seconds

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22
Q

5 large boxes (25 small boxes) on EKG paper represents what amount of time?

A

1 second

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23
Q

What is the interval between the beginning of the P wave, and the Q/R wave (whichever is present)?

A

PR interval

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24
Q

What is the interval between the end of the S (or R) wave, and the beginning of the T wave?

A

ST segment

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25
Q

What is the QRS interval?

A

Time between onset of the Q wave, to the end of the S wave

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26
Q

What is the QT interval?

A

Time between the onset of the Q wave, and the end of the T wave

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27
Q

What is the normal duration for the P wave?

A

1-2 small boxes

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28
Q

What is the normal duration of the PR interval?

A

3-5 small boxes

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29
Q

What is the normal duration of the QRS complex?

A

<1 to 3 small boxes

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30
Q

What is the normal duration of the ST segment?

A

Roughly half of R-R interval

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31
Q

What is the normal duration of the QT interval?

A

Variable (with HR)

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32
Q

What are the precordial leads?

A

V1, V2, V3, V4, V5, V6

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33
Q

What are the limb leads?

A

I, II, & III

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34
Q

What are the three augmented lead?

A

aVR, aVL, aVF

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35
Q

Lead I begins and ends where?

A

Right arm to left arm

36
Q

Lead II begins and ends where?

A

Right arm to left leg

37
Q

Lead III begins and ends where?

A

Left leg to left arm

38
Q

Where is the positive electrode for aVR?

A

Right arm

39
Q

Where is the positive electrode for aVL?

A

Left arm

40
Q

Where is the positive electrode for aVF?

A

Foot

41
Q

Where is V1 placed on the chest?

A

4th intercostal space, along the right sternal border

42
Q

Where is V2 placed on the chest?

A

4h intercostal space along the left sternal border

43
Q

Where is V4 placed on the chest?

A

5th left intercostal space in the midclavicular line

44
Q

Where is V3 placed on the chest?

A

Between V2 and V4

45
Q

Where is V5 placed on the chest?

A

In line with V4, on the anterior axillary line

46
Q

Where is V6 placed on the chest?

A

In line with V4 and V5, on the midaxillary line

47
Q

What are the three features you look at in an EKG?

A

Rate/regularity
Mean QRS axis
Rhythm

48
Q

What are the two components that you assess for, for an EKG rhythm?

A

Intervals

Waveform morphologies

49
Q

What is the best way to determine the HR on an EKG?

A

R to R interval

300 / (# of large boxes) = rough HR

50
Q

Why is the T wave (ventricular repolarization) in the same direction as the R waveform (ventricular depolarization)?

A

The + electric potential spreads from endocardial to epicardial, then repolarization spreads from epicardial to endocardial

51
Q

What does the U wave represent?

A

Repolarization of papillary, septum, or purkinje fibers

52
Q

What is the cause of the EKG findings of a STEMI?

A

Current is flowing between injured and normal

areas of the heart

53
Q

What is characteristic of a first degree AV block?

A

PR interval >200 ms (5 small boxes), but all P wave followed by a QRS complex

54
Q

What is characteristic of a second degree AV block?

A

More P wave than QRS complexes, but majority normal

55
Q

What is characteristic of a third degree AV block?

A

None of the P waves are generating a QRS
complex

Thus Heart is being paced from below the
AV node

56
Q

The magnitude of the vector/the EKG depolarization is reflecting what physiologically?

A

More muscle undergoing depolarization

57
Q

Which lead is the 0 degree line?

A

Lead I

58
Q

The voltage of a depolarization will be greatest when its vector is (parallel/perpendicular) to the EKG lead, and least when?

A
greatest = parallel
Least = perpendicular
59
Q

True or false: it is physiological to have a heart that is not exactly at 60 degrees relative to Lead I, and it is normal if this change within an individual

A

False– it is normal to not have 60 degrees, but it should be constant.

Changing axis = pathological finding

60
Q

What is the angle between lead I and lead II?

A

60 degrees

61
Q

What is the angle between lead I and lead III?

A

120 degrees

62
Q

What is the angle between lead I and lead aVL?

A

-30 degrees

63
Q

What is the angle between lead I and lead aVF?

A

90 degrees

64
Q

What is the angle between lead I and lead aVR?

A

210 degrees

65
Q

What is the axis of rotation if you see a positive deflection in lead I and aVF?

A

Normal axis

66
Q

What is the axis of rotation if you see a negative deflection in lead I and a positive deflection in aVF?

A

RAD

67
Q

What is the axis of rotation if you see a negative deflection in lead I and aVF?

A

“no man’s land”

68
Q

What is the axis of rotation if you see a positive deflection in lead I and a negative deflection in aVF?

A

LAD

69
Q

What type of deviation will obesity cause?

A

LAD

70
Q

What type of deviation will LVH cause?

A

LAD

71
Q

What type of deviation will RVH cause?

A

RAD

72
Q

What type of deviation will a LBB cause?

A

LAD

73
Q

What type of deviation will a RBB cause?

A

RAD

74
Q

What type of deviation will a tall stature cause?

A

RAD

75
Q

What type of deviation will a supine position cause?

A

RAD

76
Q

Why is the Q wave negative?

A

Septum depolarizes from the left to the right

77
Q

Why is the R wave positive?

A

Depolarization straight down septum

78
Q

What is the cause of the S wave?

A

Left ventricle depolarizes from left to right

79
Q

What are the two major causes of increased voltage of the QRS?

A

Hypertrophy

Thin chest

80
Q

What are the three major causes of decreased voltage of the QRS?

A

Previous MI
Fluid
Large chest (COPD)

81
Q

What is the cause of ST depression?

A

Subendocardial injury

82
Q

What is the cause of ST elevation?

A

Epicardial injury

83
Q

Charges flow toward or away from the direction of injury

A

Toward

84
Q

A PR interval greater than 0.2 seconds is indicative of what?

A

AV block

85
Q

A PR interval of less than .12 is indicative of what?

A

Pre-excitation

86
Q

A QRS complex than lasts longer than .12 seconds is indicative of what?

A

RBB or LBB

87
Q

What is the rule for determining if the QT interval is normal?

A

less than half of the R-R interval