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

Electrocardiogram: EKG/ECG Flashcards

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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
Chest electrodes & leads:
v1, v2, v3, v4, v5, v6
26
Where does v1 go?
Fourth intercostal space on the right sternum
27
Where does v2 go?
Fourth intercostal space at the left sternum
28
Where does v3 go?
Midway between placement of V2 and V4
29
Where does v4 go?
Fifth intercostal space at the midclavicular line
30
Where does v5 go?
Anterior axillary line on the same horizontal level as V4
31
Where does v6 go?
Mid-axillary line on the same horizontal level as V4 and V5
32
What is the Isoelectric Line ?
no charge difference inside vs outside of cardiac myocyte, no movement of ions
33
What is depolarization?
primarily + sodium flowing into cells
34
What is repolarization?
primarily + potassium flowing out of cells
35
What is Positive deflection ?
wave of depolarization toward positive electrode
36
What is Negative deflection ?
wave of depolarization toward negative electrode
37
What is the importance of the 12 lead EKG?
translates electrical signal, depolarization, and repolarization into a visual representation of the heart’s mechanics and function
38
What is the importance of telemetry EKG?
Monitor heart rate and rhythm Monitor ST segment changes
39
What is the importance of a holter EKG?
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
P wave =
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
P-R interval =
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 wave =
septal depolarization
43
QRS =
ventricular depolarization activation of the ventricles QRS complex starts just before ventricular contraction
44
ST segment =
represents the isoelectric period when the ventricles are in between depolarization and repolarization ST segment abnormality = cardiac ischemia
45
T wave =
ventricular repolarization recovery wave
46
What are the EKG Complexes>
p wave P-R interval QRS complex ST segment T wave
47
what is an action potential?
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
Phase 4: The resting phase
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
Phase 0: Depolarization
action potential is triggered by SA node Fast Na+ channels open = Na+ leaks into the cell = less negative environment
50
Phase 1: Early repolarization
TMP is now slightly positive Some K+ channels open = outward flow of K+ returns the TMP to approximately 0 mV
51
Phase 2: The plateau phase
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
Phase 3: Repolarization
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
ECG voltage:
Small box: 1mm =.04 sec Large box: 5mm =.20 sec 5 Large boxes = 1 second
54
Interpreting ECG: HR
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
Heart rate determination 3 second marks:
Count number of Q wave peaks between 3 second marks = 15 large boxes Multiple by 10 = HR
56
Rule of 300
Count number of boxes from one Q wave peak to the next 300/# of large boxes = HR Used with normal rhythm HR
57
Normal sinus rhythm
Rate between 60 and 100 beats per minute (bpm) SA Node in control Rhythm is regular
58
dysrhythmia
Alteration in rate and rhythm Ectopic Focus/Foci > Excitable group of cells = lower Action potential threshold > irritable cell
59
Causes of ectopic foci
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
Recognizing normal from abnormal EKG
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
P wave: Atrial Depolarization
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
Elongated PR Interval =
delay in signal from atria to ventricles check PR interval - will be <.2 seconds or 1 large box
63
QRS Wave: Ventricular depolarization
check QRS wave: size (wider than 3 small blocks) shape distance between R waves (exercise)
64
What is the ST segment?
Depression measured in mm – each small box on EKG strip is one mm Gives information about myocardial ischemia
65
ST Segment depression:
correlates with myocardial ischemia – non full thickness ischemia - unstable angina
66
ST Segment elevation:
correlates with myocardial infarction – coronary artery blockage - full thickness ischemia
67
St segment changes
Elevation = 4 small boxes Depression = 3 small boxes
68
Normal sinus rhythm rate =
60-100 bpm
69
Bradycardia =
< 60 bpm
70
Tachycardia =
> 100 bpm
71
Premature ventricular contraction (pvc)
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
Premature ventricular contractions are common - They're also called:
Premature ventricular complexes Ventricular premature beats Ventricular extrasystoles
73
Premature ventricular contractions can be associated with:
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
Unifocal PVC =
from one spot on the ventricle wall
75
Multifocal PVC =
from two or more spots on the ventricle wall
76
PVC rhythm =
Bigeminy: every other beat Trigeminy: every third beat Quadrageminy: every fourth beat
77
PVC Couplet:
two consecutive pvcs
78
Ventricular tachycardia =
>3 pvcs in a row
79
VTach =
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
Rapid heartbeat =
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
Ventricular fibrillation =
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
Atrial flutter =
the atria beat regularly, but faster than usual and more often than the ventricles Example = four atrial beats to every one ventricular beat
83
Atrial fibrillation =
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
Atrial fibrillation symptoms =
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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