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Cardiac Pathologies > EKG (Electrocardiogram) > Flashcards

EKG (Electrocardiogram) Flashcards

1
Q

EKG

The graphic representation of depolarization of the heart → It is a recording of the heart’s electrical activity

A

EKG

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2
Q

Electrical current moving toward the positive electrode causes…

A

positive deflection

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3
Q

Electrical current moving away from the positive electrode causes…

A

negative deflection

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4
Q

true or false: EKG measure the function of the heart

A

FALSE

measure only electrical activity

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5
Q

EKG test looks at…

A
  • Rate
  • Rhythm
  • Axis
  • Hypertrophy
  • Infarction (ischemia, injury, and other problems)
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6
Q

Physiologic properties of myocardial cells

A
  • Automaticity
  • Rhythmicity
  • Conductivity
  • Excitability
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7
Q

What is the RESTING/POLARIZED STATE of myocardium:

A

Negative charge inside of cell membrane (K+)

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8
Q

depolarization of the myocardium occurs as

A

Myocytes (inside of myocardial cells) become positive and contract → moves as a wave through the myocardium

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9
Q

myocardial REPOLARIZATION (relaxation) occurs as

A

Myocardial cells return to resting negative charge inside

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10
Q

in a positive deflection, the wave of depolarization moves towards the positive electrode. In an ISOELECTRIC DEFLECTION the wave of depolarization moves…

A

perpendicular to (+) electrode

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11
Q

mediator of the cardiac sympathetic nervous system

A

Norepinephrine

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12
Q

mediator of the cardiac parasympathetic nervous system

A

Acetylcholine

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13
Q

action of sympathetic activity in the heart

A
  • Increase rate of SA node
  • Increase rate of AV conduction
  • Increase excitability
  • Increase force of contraction (inotropic)
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14
Q

Cardiac conduction system is composed of:

A
  1. Sino-Atrial node
  2. Atrioventricular node
  3. Bundle of His
  4. Left and Right Bundle Branches
  5. Purkinje Fibers
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15
Q

what is the sinus rhythm?

A

any cardiac rhythm where depolarisation of the cardiac muscle begins at the sinus node. It is characterised by the presence of correctly oriented P waves on the electrocardiogram (ECG). Sinus rhythm is necessary, but not sufficient, for normal electrical activity within the heart.

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16
Q

Depolarization wave emitted by SA node spreads throughout both atria ➔ produces
______ on EKG

A

P wave

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17
Q

the only conduction path between the atria and the ventricles

A

AV node

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18
Q

what does the PR segment represents in the EKG?

A

Depolarization slows within the AV node before depolarization is conducted to ventricles → allows blood to finish passing from atria to ventricles

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19
Q

After depolarization slows through the AV node → it conducts RAPIDLY through the…

A

Bundle of His to the Right and Left Bundle Branches → Purkinje Fibers have “terminal filaments” which carry depolarization to the myocytes

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20
Q

what are the “terminal filaments” in the ventricular conduction system?

A

carry depolarization of the myocytes of the ventricles causing them to contract ➔ represented by the QRS complex on EKG

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21
Q

Q, R, and S waves:

A
  • Q wave = 1st downward wave of the QRS complex May or may not be present
  • R wave = 1st upward wave of the QRS complex
  • S wave = ANY downward wave PRECEDED by an upward wave
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22
Q

ST segment represents…

A

initial phase of ventricular repolarization

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23
Q

Initial plateau after QRS complex

A

ST segment, initial phase of ventricular repolarization

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24
Q

in the EKG, ventricular systole spans…

A

depolarization AND repolarization of the ventricles,
– SO it begins with the QRS and continues until the end of the T wave

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25
Q

Review of Cardiac Conduction

A

SA node → internodal pathways (to left atrium via Bachman’s bundle; to AV node via ant/middle/post internodal pathways) → AV node → Bundle of His → Right and Left bundle branch (RBB is thinner; LBB has three divisions or fascicles – anterior, septal and posterior) → Purkinje fibers (located in the ventricular walls) → myocardial cells

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26
Q

5 colored wires in telemetry or hardwire:

A
  • White clouds over Green grass
  • Black smoke over Red fire
  • Brown: center of chest (ground)
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27
Q

PR segment:

duration?

A
  • Isoelectric line after P wave
  • Also known as atrial kick
  • 0.12 – 0.20 seconds (less than 1 large square)
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28
Q

ST interval:

A
  • Full ventricular repolarization
    *
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29
Q

QT interval:

A
  • duration of ventricular systole (and repolarization)
  • Varies with heart rate because depolarization & repolarization occur faster with faster HR
    • So, QT interval measurements are often corrected for rate and are called QTc values
  • Normal QT is when it is < ½ RR interval at normal rates (~0.42 sec)
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30
Q

RR interval:

A

Use to calculate the rate → is it regular?

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31
Q

Starts at end of QRS complex and ends at T wave

A

ST segment

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32
Q

If SA node is NOT working then another area in the atria should take over with an inherent rate of

A

60-80 bpm

AV node takes over

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33
Q

Junctional Foci AKA

A

AV node

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34
Q

Ventricular foci AKA

A

Purkinje Fibers

35
Q

What structure may become the pacemaker if SA or AV node aren’t working or are diseased or in emergent situations

A

Ventricular Foci (Purkinje Fibers)

36
Q

3 things to consider when looking at a rhythm strip or EKG:

A
  1. Is there a P for every QRS?
  2. Is the rhythm regular?
  3. What is the rate?

These 3 things will tell you if you have a “sinus rhythm” and what type by the rate…
– Bradycardia – Normal – Tachycardia

37
Q

EKG

1 small horizontal box (1 mm) =

A

0.04 sec

38
Q

1 large horizontal box ( 5mm ) =

A

0.20 sec

39
Q

5 large horizontal boxes =

A

1 sec

40
Q

1 small vertical box =

A

0.10mV

41
Q

1 large vertical box =

A

0.50 mV

42
Q

2 large vertical squares =

A

1 mV

43
Q

duration of the p-wave

A

0.08 and 0.10 sec

(atrial depolarization)

44
Q

duration of the QRS complex:

A
  • < 0.12 seconds (less than 3 small squares)
  • Normally 0.06 - 0.10 seconds
  • IF QRS COMPLEX DURATION IS PROLONGED → CONDUCTION IS IMPAIRED WITHIN THE VENTRICLES
45
Q

IF QRS COMPLEX DURATION IS PROLONGED →

A

CONDUCTION IS IMPAIRED WITHIN THE VENTRICLEs

46
Q

Q wave duration

A

usually not >0.03 sec or is usually <25% of the amplitude of the R wave

47
Q

duration of the PR interval

A
  • Normally 0.12 – 0.20 seconds (less than 1 large square)
  • Usually isoelectric
  • Represents the time for the impulse to travel from the atria to the ventricles – represents the delay at the A-V node
48
Q

ST segment originates at the J-point and ends at the beginning of the

A

T wave

49
Q

Based on it’s elevation or depression, it is the main marker for, ischemia, injury or Infarction

A

ST segment

50
Q

Represents the final, “rapid” phase of ventricular repolarization

A

T wave

51
Q

Wave inversion in certain leads (negative T waves) can be a sign of

A

ischemia and more

52
Q

Represents the total time of ventricular systole and is a good indicator of repolarization

A

QT interval

53
Q

which leads look at the heart across the transverse plane?

A

chest leads

54
Q

which leads look at the heart in the frontal plane

A

limb leads

55
Q

how are the limb leads I, II, IIIpositioned?

A

often called Einthoven’s Triangle

56
Q

Limb Lead I depicts:

A

high lateral wall of heart

57
Q

Limb Lead II depicts:

A

inferior surface of heart

58
Q

Limb lead III depicts

A

inferior surface of heart

59
Q

Unipolar or Augmented Limb Leads look at what?

A
  • Lead aVR looks at nothing in the left ventricle
  • Lead aVL looks at high lateral wall of the heart
  • Lead aVF looks at the inferior wall of the heart
60
Q

Formation of a triaxial system (Einthoven’s Triangle)

A
  • By bringing the sides of the triangle to the common center, the positives and negatives are now clearly delineated
  • Triaxial system: By assigning degrees to the triaxial system, the axes are shown to be 60° apart
61
Q

Formation of an hexaxial and semicircle reference systems

A
  • By pushing all these leads to the center, a hexaxial reference is formed
  • Central axis point is the AV node
  • EACH LIMB LEAD RECORDS FROM A DIFFERENT ANGLE → this provides a different view of the same cardiac activity
62
Q

limb leads

A
63
Q

Precordial Leads location

A
  • Precordial Leads are unipolar and all are POSITIVE
  • V1 through V6 view the horizontal plane of the heart
  • V1: 4th ICS R of sternal border
  • V2: 4th ICS @ L sternal border
  • V3: equal distance between V2 and V4
  • V4: 5th ICS and L midclavicular line
  • V5: 5th ICS and ant axillary line
  • V6: 5th ICS and mid axillary line
64
Q

V1, 2: Right chest leads

A
  • Looks at right ventricle
  • V2 describes straight line directly from the front to the back of patient
65
Q

V3, 4: Located over interventricular septum

A

The left/right bundle branches flow through the septum

66
Q

V5, V6: left chest leads looks at

A

Looks at left ventricle

67
Q

The center AXIS of the precordial leads is considered to be the

A

AV node in the heart

68
Q

When observing precordial leads V1-6, you will see gradual changes in all of the waves as the position of the positive electrode changes

A

The QRS in V1 will be negative and will progress to positive by V6

69
Q

Cardiac axis refers to the

A

direction of depolarization as it passes through the heart

  • A vector (arrow) is used to demonstrate the direction of depolarization as well as the magnitude of depolarization
  • Depolarization that moves away from a (+) electrode, will have a (-) deflection
  • Depolarization that moves towards a (+) electrode, will have a (+) deflection
70
Q

Mean QRS vector =

A

the sum of all the smaller vectors of ventricular depolarization

71
Q

Origin of mean QRS vector =

A

AV Node

72
Q

Because depolarization vectors of left ventricle are larger than those of right ventricle…

A

MEAN QRS VECTOR points down and toward the LEFT (between 0 - 90°)

(Varies in individuals by size and age)

73
Q

when axis moves toward the hypertrophied region

A

hyperthrophy

74
Q

Axis moves away from infarcted region

A

INFARCTION

75
Q

Axis occurs in frontal plane → related to ______ leads

A
  • limb
  • Referred to as AXIS DEVIATION
76
Q

Axis occurs in horizontal plane → related to _______ leads

A
  • precordial
  • Referred to as AXIS ROTATION
77
Q

3 things to consider when looking at a rhythm strip or EKG:

A
  • P wave for every QRS
  • Rhythm
  • Rate
78
Q

reading EKG steps:

A

Regularity:

  1. Check for P wave for every QRS
  2. Identify the R wave
  3. Mark the distance between the R waves (RR Interval)
  4. Assess if the distance is consistent
79
Q

Calculating the Rate by Counting Boxes

A
  • Find a R on athink line
  • the count 300-150-100-75-60-50
  • Between 100 and 150: 50 ➗ 5 = 10
  • Bet 100 and 75: 25 ➗ 5 = 5
80
Q

How to measure rate: 6 Second Method

A
  • Count the number of complete complexes found between two sets of 3 second marks (equals 6 seconds) on the ECG strip and multiply by 10
  • Useful for:
    – Slow rates – Irregular rhythms
81
Q

P - R interval:

A
  • Definition: measured from the beginning of the P wave to the beginning of the QRS complex
  • Normal values = 0.12 – 0.20 sec
82
Q

QRS complex represents? Normal duration?

A
  • Definition: represents ventricular depolarization
  • Normal value: 0.06 - 0.10 sec
  • Less than 0.12 (less than 3 small squares
83
Q

what does the QRS complex represents?

A

ventricular depolarization

84
Q

What part of the EKG represents the terminal filaments?

A

QRS complex

Cardiac Pathologies (13 decks)

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