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Flashcards in EKGs Deck (87):
1

Is depolarization a process or a state?

Process

2

What is an EKG electrode detecting?

The flow of current

3

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

True

4

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

Rises above

5

What is the P wave a result of?

Atrial myocyte depolarization

6

Where does depolarization begin for each heart beat?

In the SA node

7

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

There is none--too small to detect

8

What does the Q wave represent (if present)?

Septal depolarization

9

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

Q wave, not always there

10

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

R wave, should always be there

11

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

S wave, may be present

12

What does the R wave represent?

Ventricular muscle depolarization

13

What does the T wave represent?

Repolarization of the Ventricles

14

Which part of the EKG recording represents atrial repolarization?

There is none--hidden in the R wave

15

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

Ca influx into the atrial myocytes, maintaining the depolarization

16

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

Going through the Purkinje fibers

17

What does the S wave represent?

Ventricular muscle depolarization away from the electrode

18

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

Plateau of the AP d/t Ca influx

19

What is the chart speed of EKG paper?

25 mm/min

20

10 mm on the EKG paper corresponds to what mV?

1 mV

21

5 small boxes on EKG paper represent how many seconds?

0.2 seconds

22

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

1 second

23

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

PR interval

24

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

ST segment

25

What is the QRS interval?

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

26

What is the QT interval?

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

27

What is the normal duration for the P wave?

1-2 small boxes

28

What is the normal duration of the PR interval?

3-5 small boxes

29

What is the normal duration of the QRS complex?

<1 to 3 small boxes

30

What is the normal duration of the ST segment?

Roughly half of R-R interval

31

What is the normal duration of the QT interval?

Variable (with HR)

32

What are the precordial leads?

V1, V2, V3, V4, V5, V6

33

What are the limb leads?

I, II, & III

34

What are the three augmented lead?

aVR, aVL, aVF

35

Lead I begins and ends where?

Right arm to left arm

36

Lead II begins and ends where?

Right arm to left leg

37

Lead III begins and ends where?

Left leg to left arm

38

Where is the positive electrode for aVR?

Right arm

39

Where is the positive electrode for aVL?

Left arm

40

Where is the positive electrode for aVF?

Foot

41

Where is V1 placed on the chest?

4th intercostal space, along the right sternal border

42

Where is V2 placed on the chest?

4h intercostal space along the left sternal border

43

Where is V4 placed on the chest?

5th left intercostal space in the midclavicular line

44

Where is V3 placed on the chest?

Between V2 and V4

45

Where is V5 placed on the chest?

In line with V4, on the anterior axillary line

46

Where is V6 placed on the chest?

In line with V4 and V5, on the midaxillary line

47

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

Rate/regularity
Mean QRS axis
Rhythm

48

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

Intervals
Waveform morphologies

49

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

R to R interval

300 / (# of large boxes) = rough HR

50

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

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

51

What does the U wave represent?

Repolarization of papillary, septum, or purkinje fibers

52

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

Current is flowing between injured and normal
areas of the heart

53

What is characteristic of a first degree AV block?

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

54

What is characteristic of a second degree AV block?

More P wave than QRS complexes, but majority normal

55

What is characteristic of a third degree AV block?

None of the P waves are generating a QRS
complex

Thus Heart is being paced from below the
AV node

56

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

More muscle undergoing depolarization

57

Which lead is the 0 degree line?

Lead I

58

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

greatest = parallel
Least = perpendicular

59

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

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

Changing axis = pathological finding

60

What is the angle between lead I and lead II?

60 degrees

61

What is the angle between lead I and lead III?

120 degrees

62

What is the angle between lead I and lead aVL?

-30 degrees

63

What is the angle between lead I and lead aVF?

90 degrees

64

What is the angle between lead I and lead aVR?

210 degrees

65

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

Normal axis

66

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

RAD

67

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

"no man's land"

68

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

LAD

69

What type of deviation will obesity cause?

LAD

70

What type of deviation will LVH cause?

LAD

71

What type of deviation will RVH cause?

RAD

72

What type of deviation will a LBB cause?

LAD

73

What type of deviation will a RBB cause?

RAD

74

What type of deviation will a tall stature cause?

RAD

75

What type of deviation will a supine position cause?

RAD

76

Why is the Q wave negative?

Septum depolarizes from the left to the right

77

Why is the R wave positive?

Depolarization straight down septum

78

What is the cause of the S wave?

Left ventricle depolarizes from left to right

79

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

Hypertrophy
Thin chest

80

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

Previous MI
Fluid
Large chest (COPD)

81

What is the cause of ST depression?

Subendocardial injury

82

What is the cause of ST elevation?

Epicardial injury

83

Charges flow toward or away from the direction of injury

Toward

84

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

AV block

85

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

Pre-excitation

86

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

RBB or LBB

87

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

less than half of the R-R interval