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Cardio pulm exam 2 > Electrocardiogram: EKG/ECG > Flashcards

Electrocardiogram: EKG/ECG Flashcards

1
Q

What is EKG?

A

Using surface electrodes to record the electrical activity of the heart

electrical activity correlates to mechanical function

Takes electrical “snapshots” of the heart at different angles

each electrical impulse = a cardiac contraction

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2
Q

What Information from EKG?

A

heart rate
heart rhythm
heart size
ischemia/infarction
drug and electrolyte abnormalities

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3
Q

Electrical impulse sequence =

A

starts with sinoatrial node -> Atrioventricular node ->
bundle of his ->
purkinje fibers ->

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4
Q

What is Isoelectric activity?

A

cardiac cells at rest, no relative movement of ions

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5
Q

What is Depolarization ?

A

muscle contraction due to movement of sodium, potassium, and calcium

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6
Q

What is repolarization ?

A

muscle relaxation due to return of sodium, potassium, and calcium to resting state

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7
Q

What is the normal conduction pathway?

A

SA Node sends an electrical impulse to the right and left atria

Atria contract and pump blood to the ventricles

Atrioventricular node (AV) stimulated – base of the right atrium

Slows the signal allowing time for the ventricles to fill

Electrical signal then travels down the bundle of His and branches to the right and left ventricles

Purkinje fibers at the base of the ventricles

Ventricular contraction

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8
Q

Two types of cardiac cells:

A

Conducting: 1%
Contracting: 99%

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9
Q

What is the EKG of Cardiac muscle cells at rest ?

A

(slight negative)

resting polarized state

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10
Q

What is the EKG of depolarization of the cells ?

A

(wave of positive or less negative due to sodium influx)

Endocardium to Epicardium -> contraction

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11
Q

What is the EKG of repolarization of the cells ?

A

(wave of negative or less positive due to potassium efflux)

Epicardium to Endocardium -> relaxation

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12
Q

Ventricular wall: epicardium and endocardium

A

Depolarization goes from the endocardium to epicardium

Repolarization is opposite and goes from the epicardium to endocardium

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13
Q

With contraction, blood is moved from:

A

Atrium to ventricles

Right ventricle to pulmonary circulation

Left ventricle to systemic circulation

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14
Q

Standard 12 lead EKG includes:

A

6 chest electrodes
4 limb electrodes

12 leads or views of the heart

Limb leads: I, II, III

Augmented leads: avr, avl, avf

Chest Leads: V1 – V6

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15
Q

Extremity electrode and placement:

A

RA (Right Arm) - Anywhere between the right shoulder and right elbow; modified to right anterior shoulder

LA(Left Arm) - Anywhere between the left shoulder and the left elbow; modified to left anterior shoulder

LL (Left Leg) - Anywhere below the left torso and above the left ankle; modified to LLQ

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16
Q

What are Limb leads?

A

Leads I, II and III

electrodes that form these signals are located on the limbs – one on each arm and one on the left leg – electrode on right leg is neutral and plays no role in the EKG other than completing the circuit

The limb leads form the points of what is known as Einthoven’s triangle

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17
Q

What is lead I ?

A

the voltage between the +LA electrode and -RA electrode

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18
Q

What is lead II ?

A

the voltage between the +LL electrode and the -RA electrode

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19
Q

What is lead III ?

A

the voltage between the +LL electrode and the -LA electrode

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20
Q

What are Augmented limb leads?

A

Leads aVR, aVL, and aVF

They are derived from the same three electrodes as leads I, II, and II

they use a central terminal created by a combination of inputs from two limb electrode

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21
Q

What is Lead augmented vector right (aVR) ?

A

combination of the left arm electrode and the left leg electrode

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22
Q

What is Lead augmented vector left (aVL) ?

A

combination of the right arm electrode and the left leg electrode

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23
Q

What is Lead augmented vector foot (aVF) ?

A

combination of the right arm electrode and the left arm electrode

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24
Q

Leads I, II, and III, augmented limb leads aVR, aVL, and aVF calculate what?

A

the heart’s electrical axis in the frontal plane = 6 views

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25
Q

Chest electrodes & leads:

A

v1, v2, v3, v4, v5, v6

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26
Q

Where does v1 go?

A

Fourth intercostal space on the right sternum

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27
Q

Where does v2 go?

A

Fourth intercostal space at the left sternum

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28
Q

Where does v3 go?

A

Midway between placement of V2 and V4

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29
Q

Where does v4 go?

A

Fifth intercostal space at the midclavicular line

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30
Q

Where does v5 go?

A

Anterior axillary line on the same horizontal level as V4

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31
Q

Where does v6 go?

A

Mid-axillary line on the same horizontal level as V4 and V5

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32
Q

What is the Isoelectric Line ?

A

no charge difference inside vs outside of cardiac myocyte, no movement of ions

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33
Q

What is depolarization?

A

primarily + sodium flowing into cells

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34
Q

What is repolarization?

A

primarily + potassium flowing out of cells

35
Q

What is Positive deflection ?

A

wave of depolarization toward positive electrode

36
Q

What is Negative deflection ?

A

wave of depolarization toward negative electrode

37
Q

What is the importance of the 12 lead EKG?

A

translates electrical signal, depolarization, and repolarization into a visual representation of the heart’s mechanics and function

38
Q

What is the importance of telemetry EKG?

A

Monitor heart rate and rhythm

Monitor ST segment changes

39
Q

What is the importance of a holter EKG?

A

Portable ECG = typically worn 24+ hours for Dx purposes

Monitor heart rate and rhythm over several days to weeks

Correlate signs and symptoms to heart mechanics

40
Q

P wave =

A

atrial depolarization

activation of the atria

Normally the right atrium depolarizes slightly earlier than left atrium since the depolarization wave originates in the sinoatrial node

41
Q

P-R interval =

A

onset of the P wave to the start of the QRS complex

It reflects conduction through the AV node

normal PR interval: 120 – 200 ms (0.12-0.20s) = three to five small squares

1 small square = .04 seconds

42
Q

Q wave =

A

septal depolarization

43
Q

QRS =

A

ventricular depolarization

activation of the ventricles

QRS complex starts just before ventricular contraction

44
Q

ST segment =

A

represents the isoelectric period when the ventricles are in between depolarization and repolarization

ST segment abnormality = cardiac ischemia

45
Q

T wave =

A

ventricular repolarization

recovery wave

46
Q

What are the EKG Complexes>

A

p wave
P-R interval
QRS complex
ST segment
T wave

47
Q

what is an action potential?

A

electrical stimulation created by ion fluxes through specialized channels in the membrane of cardiomyocytes that leads to cardiac contraction = typically -90mV to 0mV

The action potential in typical cardiomyocytes is composed of 5 phases (0-4), beginning and ending with phase 4

48
Q

Phase 4: The resting phase

A

resting potential in a cardiomyocyte is −90 mV due to a constant outward leak of K+

Na+ and Ca2+ channels are closed during resting phase

49
Q

Phase 0: Depolarization

A

action potential is triggered by SA node

Fast Na+ channels open = Na+ leaks into the cell = less negative environment

50
Q

Phase 1: Early repolarization

A

TMP is now slightly positive

Some K+ channels open = outward flow of K+ returns the TMP to approximately 0 mV

51
Q

Phase 2: The plateau phase

A

Ca2+ channels are open = constant inward current of Ca2+

K+ channels open = outward current of K+

These two countercurrents are electrically balanced = the TMP is maintained at a plateau  0 mV throughout phase 2

52
Q

Phase 3: Repolarization

A

Ca2+ channels inactivated = inward CA2+ flow stops

Outflow of K+ = TMP back towards resting potential of −90 mV to prepare the cell for a new cycle of depolarization

53
Q

ECG voltage:

A

Small box: 1mm =.04 sec

Large box: 5mm =.20 sec

5 Large boxes = 1 second

54
Q

Interpreting ECG: HR

A

Heart rate can be easily calculated from the ECG strip

When the rhythm is regular, the heart rate is 300 divided by the number of large squares between the QRS complexes

(300/5 = 60)

55
Q

Heart rate determination
3 second marks:

A

Count number of Q wave peaks between 3 second marks = 15 large boxes

Multiple by 10 = HR

56
Q

Rule of 300

A

Count number of boxes from one Q wave peak to the next

300/# of large boxes = HR

Used with normal rhythm HR

57
Q

Normal sinus rhythm

A

Rate between 60 and 100 beats per minute (bpm)

SA Node in control

Rhythm is regular

58
Q

dysrhythmia

A

Alteration in rate and rhythm

Ectopic Focus/Foci
> Excitable group of cells = lower Action potential threshold
> irritable cell

59
Q

Causes of ectopic foci

A

ischema/hypoxia of myocardium

sympathetic discharge - anxiety, exercises

acidosis

alteration in electrolytes (decreased K+)

excessive stretch of myocardium

pharmacological agents
> SNS mimetics - caffeine
> anti-arrhythmic drugs
> digitalis

60
Q

Recognizing normal from abnormal EKG

A

Pattern Recognition

Check QRS wave -size, shape, distance

Check P wave -size/shape

Check PR interval

Check T wave -size/shape

Check ST segment

61
Q

P wave: Atrial Depolarization

A

Size and shape

P duration < 0.12 sec = less than 3 small boxes

P amplitude < 2.5 mm = <.25 mV

Tall P wave = right atria enlargement = right heart failure

Elongated p wave = myocardial fibrosis, atrial fibrillation

62
Q

Elongated PR Interval =

A

delay in signal from atria to ventricles

check PR interval - will be <.2 seconds or 1 large box

63
Q

QRS Wave: Ventricular depolarization

A

check QRS wave:

size (wider than 3 small blocks)

shape

distance between R waves (exercise)

64
Q

What is the ST segment?

A

Depression measured in mm – each small box on EKG strip is one mm

Gives information about myocardial ischemia

65
Q

ST Segment depression:

A

correlates with myocardial ischemia – non full thickness ischemia - unstable angina

66
Q

ST Segment elevation:

A

correlates with myocardial infarction – coronary artery blockage - full thickness ischemia

67
Q

St segment changes

A

Elevation = 4 small boxes

Depression = 3 small boxes

68
Q

Normal sinus rhythm rate =

A

60-100 bpm

69
Q

Bradycardia =

A

< 60 bpm

70
Q

Tachycardia =

A

> 100 bpm

71
Q

Premature ventricular contraction (pvc)

A

extra heartbeats that begin in one of your heart’s ventricles = These extra beats disrupt your regular heart rhythm

These extra contractions usually beat sooner than the next expected regular heartbeat And they often interrupt the normal order of pumping

Can manifest as a feeling of fluttering or a skipped beat in your chest

72
Q

Premature ventricular contractions are common - They’re also called:

A

Premature ventricular complexes

Ventricular premature beats

Ventricular extrasystoles

73
Q

Premature ventricular contractions can be associated with:

A

meds including decongestants and antihistamines

Alcohol/drugs
caffeine
tobacco
exercise
anxiety

Injury to the heart muscle from coronary artery disease, congenital heart disease, high blood pressure or heart failure

74
Q

Unifocal PVC =

A

from one spot on the ventricle wall

75
Q

Multifocal PVC =

A

from two or more spots on the ventricle wall

76
Q

PVC rhythm =

A

Bigeminy: every other beat

Trigeminy: every third beat

Quadrageminy: every fourth beat

77
Q

PVC Couplet:

A

two consecutive pvcs

78
Q

Ventricular tachycardia =

A

> 3 pvcs in a row

79
Q

VTach =

A

defined as 3 or more irregular heartbeats in a row, originating from the ventricle, a rate of more than 100 beats a minute

If VTach lasts for more than 6 seconds at a time, it can become life-threatening = V Fibrillation

80
Q

Rapid heartbeat =

A

doesn’t give your heart enough time to fill with blood before it contracts again = reduced blood flow to the rest of your body

81
Q

Ventricular fibrillation =

A

heart rhythm problem that occurs when the heart beats with rapid, erratic electrical impulses. This causes the ventricles to quiver uselessly, instead of pumping blood.

Significant drop in blood pressure limiting blood supply to your vital organs

an emergency that requires immediate medical attention

it is the most frequent cause of sudden cardiac death

automated external defibrillator (AED) necessary to reset the electrical rhythm

medications and implantable devices that can restore a normal heart rhythm

82
Q

Atrial flutter =

A

the atria beat regularly, but faster than usual and more often than the ventricles

Example = four atrial beats to every one ventricular beat

83
Q

Atrial fibrillation =

A

arrhythmia that can lead to blood clots, stroke, heart failure

At least 2.7 million Americans are living with AFib.

atria beat chaotically and irregularly — out of coordination with the ventricles

84
Q

Atrial fibrillation symptoms =

A

often include heart palpitations, shortness of breath and weakness

Leads to cardiac compromise if frequency and duration are not addressed with medication

Cardio pulm exam 2 (8 decks)

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