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Flashcards in Lectures for exam 1 Deck (90):
1

Define Automaticity

Poduce impulse without stimulation

2

Which cells exhibit Automaticity?

Pacemaker cells in SA node

3

Define Excitability

Ability to respond to an electrical stimulus

4

Which cells exhibit Excitability?

Electrical conduction cells (myocardial cells)

5

Define Conductivity

Ability to transmit electrical signal from cell to cell

6

Which cells exhibit Conductivity?

Electrical conducting cells (myocardial cells)

7

3 cells of the heart?

1. Electrical conducting cells
2. Myocardial cells
3. Pacemaker cells

8

Which cells are the hard wiring of the heart?

Electrical conducting cells

9

Which cells are the contractile machinery of the heart?

Myocardial cells

10

Which cells are the muscle cells of the atria and ventricles?

Myocardial cells

11

Which cells are able to depolarize spontaneously and are the normal electrical power source?

Pacemaker cells

12

What determines the rate of the pacemaker cells? (2 things)

1. Innate electrical characteristics of cells
2. External neurochemical input

13

Examples of electrical conducting cells?

AV Node, His bubdle, LBB, RBB, Ant and Post Fascicles, Purkinge fibers

14

Pathway of electricity in the heart to myocardial cells?

Pacemaker->Contracting pathway->myocardial cells

15

What is the Cardiomyocyte Action Potential responsible for initiating?

Initiating each cardiac contraction

16

What initiates cardiac contraction?

Cardiomyocyte Action Potential

17

What are the 2 types of Cardiomyocyte Action Potential?

Spontaneous and Non-spontaneous

18

Are pacemaker cells in the SA node spontaneous or non-spontaneous Cardiomyocyte Action Potential?

Spontaneous

19

Are cardiac muscle cells spontaneous or non-spontaneous Cardiomyocyte Action Potential?

Non-spontaneous

20

What chemicals increases rate of pacemaker cell discharge causing increased heart rate?

Catecholamines (Epi and Norepi)

21

What chemical causes the decrease of pacemaker cell discharge thus slowing the heart rate?

Acetylcholine

22

What releases Acetylcholine?

Released during vagal stimulation

23

What causes myocardial cells to contract?

Depolarization which releases calcium from sacroplasmic reticulum

24

What type of coupling do myocardial cells exhibit?

Excitation-contraction coupling

26

What muscle components do myocardial cells contain?

Actin and myosin

27

What does the EKG waveform primarily reflect?

Electrical activity of myocardial cells

28

What are the 3 main characteristics of the EKG waveform?

1. Duration in ms
2. Amplitude in mV
3. Configuration

29

When does ventricular excitation begin?

Begins at atrial relaxation

30

Time duration of small square on EKG paper?

0.04sec

31

Time duration of large square on EKG paper?

0.20 sec

32

How many small squares make up a large square on EKG paper?

5 small squares long and high

33

How many precordial leads are there?

Six

34

Precordial leads aka?

Chest leads or V leads

35

Which are the six precordial leads?

V1-V6

36

How many Limb Leads are there?

Three

37

What are the three Limb Leads called?

Lead 1
Lead 2
Lead 3

38

Lead 1 degree? Which arm positive and negative?

0º. Left arm positive, right arm negative.

39

Lead 2 degree? What is positive and which arm negative?

60º. Leg positive, right arm negative.

40

Lead 3 degree? What is positive and which arm negative?

120º. Leg positive, left arm negative

41

What are the 3 augmented limb leads?

aVL
aVR
aVF

42

aVL degree? Positive and negative?

-30º. Left arm positive, other limbs negative.

43

aVR degree? Positive and negative?

-150º. Right arm positive, other limbs negative.

44

aVF degree? Positive and negative?

+90º. Leg positive, other limbs negative.

45

Which are the 3 anterior leads?

V2
V3
V4

46

Which are the 3 inferior leads?

II, III, aVF

47

Which are the 2 Right Ventricular leads?

aVR, V1

48

Which are the 4 Left Lateral leads?

I, aVL, V5, V6

49

Where does Atrial Excitation begin and complete?

Begin=SA node
Complete=AC node

50

What depolarized in the P-Wave?

Both atria. RA then LA.

51

Normal P-wave amplitude?

0.5-2.5mm

52

Normal P-wave duration?

0.06-0.10sec

53

Which lead does P-wave have negative deflection

aVR

54

Where does P-wave have biphasic deflection? (hint: 2)

III, V1

55

P-Wave deflection variable/unpredictable in which 3?

V2, V3, V4

56

P-wave amplitude in Right Atrial Enlargement?

>2.5mm. Normal duration.

57

What will V1 show in Right Atrial Enlargement?

Taller initial component in biphasic P-wave

58

Amplitude of P-wave in Left Atrial Enlargement?

Normal or increased

59

P-wave in Left Atrial Enlargement?

Wide, often notched

60

V1 P-wave in Left Atrial Enlargement?

Wide biphasic wave

61

PR interval is from start of what in atria to start of what in ventricles?

Time from start of atrial depolarization to start of ventricular depolarization

62

Normal time of PR Interval?

0.12 to 0.2 seconds (up to one big box)

63

What can it means if PR Inteval is more than one big box?

Heart block

64

PR Segment is from end of what in atria to beginning of what in ventricles?

Time from end of atrial depolarization to beginning of ventricular depolarization

65

What does the Q-wave reflect?

Left to right septal depolarization

66

What is a pathological Q Wave due to?

Irreversible myocardial damage.

67

When does a pathological Q Wave occur?

Hours to days after an MI

68

Duration of pathological Q Wave?

≥0.04sec

69

Depth of pathological Q Wave?

≥1/3 height of R wave

70

Which lead’s negative deflected QRS complex is not a pathological Q Wave?

aVR

71

What depolarizes in QRS-complex?

Remainder of ventricles depolarize (started with PR Segment)

72

Average vctor of QRS-complex correct flow?

0º to 90º

73

Which 2 leads have deep negatively deflected S-waves?

V1 and V2

74

What is R-Wave Progression?

Pattern of progressively increasing R-wave amplitude from right to left in V1-V6

75

Which lead do the R-Wave Progression occur in?

V1-V6

76

What is a normal QRS-interval (duration)?

Narrow is normal! 0.06-0.1sec

77

QRS-interval not more than how many small boxes?

3

78

Duration of a wide QRS-interval?

>0.1 sec

79

2 causes a wide QRS-interval?

1. Impulse generated in ventricle
2. Abberant pathway through ventricle

80

ST-segment time from end of what to start of what?

Time from end of ventricular depolarization to start of ventricular repolarization

81

What can you tell from ST-segment?

Active cardiac ischemia or infarction (STEMI)

82

STEMI height in limb leads (I, II, III)?

≥1mm

83

STEMI height in precordial leads (V1-V6)?

≥2mm

84

Tombstone or frowning face appearance?

STEMI in precordial leads (V1-V6)

85

ST depression is a sign of what?

Cardiac ischemia

86

T-waves represent what?

Repolarization

87

QT-interval is beginning of what to end of what?

Beginning of ventricular depolarization to end of ventricular repolarization

88

QT-interval is inversely proportial to what?

Heart rate

89

What is a normal precent of the QT-interval?

40%

90

Normal QT-interval is where between two QRS complexes?

<1/2 way

91

What will a fast heart rate do to the length of the QT-interval?

Shorten it