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259 - physiology > lab 1: ECG analysis LAB EXAM > Flashcards

lab 1: ECG analysis LAB EXAM Flashcards

1
Q

explain why the heart is the most simple organ

A

It secretes no hormones, breaks down no enzymes, detects no external stimuli, and neither adds nor withdraws substances from the blood. It is a pump

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2
Q

where does innervation of the heart occur

A

medulla

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3
Q

what happens to the heart, resp and mettabolism during sleep

A

they are maintinaed at effieicent minimal levels

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4
Q

what is the muscle layer of the heart called

A

myocardium

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5
Q

what is the function of the contractions of the myocardium

A

Contractions of the myocardium force blood in and out of the chambers on a
two-stage journey through the heart

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6
Q

what is the functiuon of the valves in the heart

A

regulate the flow of blood into and out of the proper chambers, opening and close with each contraction of the myocardium

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7
Q

where does co2 saturated blood enter the heart

A

rigth atrium

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8
Q

how does co2 saturated blood enter the right atrium

A

VENA CAVA

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9
Q

after blood is in the right ventricle, where does it get pumped out through

A

thrpoug h the pulmonary artery

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10
Q

what kind of blood does pulm artery carry

A

deoxy blood

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11
Q

where do pulmonary arteries carry blood and why

A

The pulmonary artery carries blood to the lungs, where it exchanges its carbon dioxide for oxygen inhaled by the lungs;

carbon is exhales

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12
Q

how does new oxygenated blood get to the heart

A

pulm veins

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13
Q

where do pulm veins carry oxy blood

A

into the left atrium

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14
Q

what is the function of the atrium

A

reservoirs for the ventricles, assuring constant flow of blood through the heart and acting as a ventricular priimer

(the atria’s pumping serves to adequately fill the ventricles prior to
each ventricular contraction)

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15
Q

aFter blood is in the left ventricle, where does it get pumped out throug h

A

the aorta and out into the body to carry nutrients to the body tissues

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16
Q

as blood gives up o2 to the tissues, what does it c=pick up along the way

A

co2 and returned to the heart

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17
Q

what is Each contraction of the myocardium preceded by

A

an action potential generated by specialized cells in the sinoatrial (SA) node, l

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18
Q

where is action potential generated in the heart

A

at the sinoatrial node

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19
Q

where is the SA node locatied

A

in the right atrium near the Sup vena cava

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20
Q

All myocardial cells are tightly joined together via BLANK, which are unique to the heart.

A

intercalated discs

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21
Q

what is the fucntion of the intercalated disks joining the myocardial cells

A

The intercalated discs have a lower resistance to electrical conductivity than the outside of the myocardium, resulting in a quick propagation of the cardiac action potential from the SA node to adjacent myocardial cells

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22
Q

why is it good that the The intercalated discs have a lower resistance to electrical conductivity than the outside of the myocardium,

A

results in a quick propagation of the cardiac action potential from the SA node to adjacent myocardial cells

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23
Q

after the signal from the SA depolarizxes the adjacent myocardial cells, where does it travel

A

the depolarisation also follows an electrical pathway that leads to the atrioventricular (AV) node

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24
Q

where is the AV ndoe located

A

at the border between the atriam and ventricles along the midline of the hear t

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25
Q

From the AV node, where does the action potential travels

A

downward toward the apex of the heart via the Bundle of His, Right and Left
Bundle Branches and the Purkinje Fibres

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26
Q

put thsee in order ( , Right and Left Bundle Branches, SA node,
, AV node and the Purkinje Fibres, Bundle of His

A 
SA node
AV node
bundle of HIS
R/L bundle brances
purkinje fibers
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27
Q

what tissue is the electrical conductive pathway composed of

A

composed of specialized non-contractile, highly conductive cardiac tissue that ensures the heart depolarizes and contracts in a sequential manner (from atria to ventricle), and as a coordinated unit.

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28
Q

why is the electrical conductive pathway composed of specialized, non contractile and highly conductive cardiac tissue

A

ensures the heart depolarizes and contracts in a sequential manner (from atria to ventricle), and as a coordinated unit.

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29
Q

as the depolarization nwave travels down the heart/pathway, waht happens to the myocardial cells

A

they depolarize and subsequently contract

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30
Q

true or false: the electrical impulses that occur at the heart do not spread throug hthe body

A

false,
These waves of electrical impulses, although occurring locally at the level of the heart, also spread through the body, eventually reaching the skin

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31
Q

what is the amplictude of voltage changes that can normally be picked up by ECg

A

1-2 mV

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32
Q

what is the function of the ECG

A

The ECG offers a reliable, non-invasive way of studying the integrity
of the heart’s electrical conductive system and allows for an overall evaluation of cardiac health.

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33
Q

what are Three words describe the heart’s electrical activity:

A

polarisation, depolarisation, and repolarisation

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34
Q

explain what the term Polarisation refers to

A

the heart at rest (i.e., no impulse, stimulation, contraction, nor measurable
electrical activity), awaiting a depolarising signal, normally from the SA node.

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35
Q

explain what the term Depolarisation means

A

is another word for the discharge of electrical energy that triggers the contraction. This depolarisation can be measured by the ECG

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36
Q

true or false: polarization can be measured by an ECG

A

no , only re or depolarization (when there is achagne in voltage) can be measured

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37
Q

what does the term repolarization mean

A

Repolarisation is the electrical recovery of the heart as the cells recharge
themselves and return to the polarised state, which can also be measured by the ECG.

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38
Q

true or false: the ECG is a measurement of the strength of myocardial contractions of the heart

A

NO false

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39
Q

what is the ECG recording

A

The ECG is a recording of the electrical impulses prior to the contraction and
relaxation of the myocardium

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40
Q

true or false: The ECG is a recording of the electrical impulses AFTER the contraction and relaxation of the myocardium

A

FALSE

PRIOR TO

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41
Q

what is the P wave/when does it occur

A

occurs as a result of the action potentials (the depolarization) that cause the atria to contract
=ATRIAL DEPOLARIZATION

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42
Q

what does the PR interval represent

A

the time required for the impulse to travel from the SA node to the AV node;

=time elapsed between the onset of atrial depolarisation and the onset of ventricular depolarisation.

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43
Q

true or false: the ventricles can contract before the atria

A

false, they should not
remember the atria act as ventricular primers, and therefore must depolarise, and consequently
contract, before the ventricles.

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44
Q

what does the QRS occur from

A

the QRS complex, occurs as a result of ventricular
depolarisation (i.e., the travel of the electrical impulse from the AV node through to the Purkinje network and all the myocardial cells of the ventricles)

=ventricular depolarixation

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45
Q

what does the ST segment represent

A

Termination of the QRS complex signifies that all
ventricular muscle fibres have been depolarized and are now in a refractory period, which is represented by the S-T segment (i.e., no deflection occurs

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46
Q

what are the 2 typical negative deflections of the QRS completex

A
  • the Q and the S waves.
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47
Q

true or false: the R wave of the QRS complex should always be present even if the Q and S waves arent?

A

true
Q and S may be absent but The relatively large R wave within the QRS complex represents the main phase of ventricular depolarisation and is always present under normalcircumstances

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48
Q

what part of the QRS complex

represents the main phase of ventricular depolarisation

A

the R wave

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49
Q

what is the T wave represent

A

which represents the repolarisation of the ventricles as the

cells recharge themselves

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50
Q

what does the QT intevenal represent

A

The entire Q-T interval represents the amount of time elapsed between
the beginning of ventricular depolarisation and the completion of ventricular repolarisation.

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51
Q

true or fale: U waves are always present on ECG

A

false
The origin and clinical significance of the U wave are still debated, but may represent the repolarisation of the Purkinje fibers.

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52
Q

why is there a delay at the AV node

A

allows the atria to fully contract and pump blood into the ventrciels before the ventricles contract (PR intevral)

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53
Q

how many vectors are there in the atrium

A

1 vector=1 wave

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54
Q

how many vectors are there through the ventricles

A

3 vectors=3 waves (QRS)

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55
Q

why is atrial repolarization usually hidden

A

because it occurs during ventricular depolarization (large QRS) so it is hiddne by the larger electrical events that generate that

56
Q

b/w impulses, what state is the heart in

A

polarized

57
Q

when the heart is a rest and there is no electtrical activtiy within the myocardium, what happens to the ECG

A

the ECG has nothing to record,

the stylus (the pen on the recorder) returns to what is called the isoelectric baseline (i.e., zero-voltage line) = the baseline

58
Q

6 limb ECG containts what leads

A

limb and augmented limb leads

59
Q

how many electrodes are placed on a patient during ECG and where (general )

A

4 electrodes (one on each wrist and one on each ankle)

3 are recording 1 ground electrode

60
Q

where is the ground electrode located

A

right leg

61
Q

explain electrode placement for lead 1 and the image resulting

A
  • right arm
    + left arm

=image of left side of heart

62
Q

explain electrode placement for lead 2 and the image resulting

A
  • right arm
    + left leg

=view f\of the apex of the heaert

63
Q

explain electrode placement for lead 3 and the image resulting

A
  • left arm

+ left leg

64
Q

explain how augmented limb leads work

A

combine 2 electrtodes to get different anglese of the heart

65
Q

where is the positive electrode on the aVF

A

on the left leg

66
Q

where is the positive electrode for avR

A

on the right arm

67
Q

where is the postive electrode for avL

A

on the left arm

68
Q

what is the paper speed for ECG recording

A

25 mm/sec

1500 mm/min

69
Q

how is an ECG paper divided

A

into small 1 mm boxes and larger 5 mm boxes

70
Q

on the x axis what are the sizes and duractions of small and large boxes

A

small box = 1 mm = 40 ms

large box = 5 mm = 200 ms

71
Q

on the y axis what are the sizes and duractions of small and large boxes

A

small box = 1 mm = 0.1 mv

2 large boxes= 10 mm = 1 mv

72
Q

what are the 3 main assessments for analyzing the strip

A

1) detecting arrythmias (using the 5 step analysis)
2) signs of hypertrophy
3) assess myuocardial damage

73
Q

what are some examples of arryhtmias (causes)

A

ectopic beats
heart block
abnomral electrial activity

74
Q

if there is an icnreased workload on the heart and myocardial hypertrophy occurs, what will happen to amplitude of the ECG waves

A

they will increase

75
Q

if there myocardial damage (ex: myocardial infarction) what can that do to the wave forms and give examples

A

it can alter them

ex: ST segment elevation/depressionn, eccessively large Q waves

76
Q

what are the 5 basic steps of the 5 step analysis

A

1) determine consistence of ryhtm ( RR int)
2) Assess HR
3) assess P wave consistency (atrial)
4) assess PR interval (av node)
5) asess qrs complex (venticles)

77
Q

the 5 step analysis is done on what lead

A

the lead with the largets (positive/upward) deflections and a clear 6 second portion

(usally lead 2)

78
Q

explain the procedure for RR interval regularity

A

SEE notes

79
Q

what is the acceptable range for RR interval regularity

A

Your average RR interval +-120 m

check that every value falls within the range

80
Q

If you have an abnormal RR interval, what would that indicate

A

SA node arryhtmia (determs heeart rate rythyms)

81
Q

explain the respiratory sinus arrythmia/accordion affect

A

When you breathe in: heart rate increases
when you breath out: heart rate decreases

this can cause spaced out and close together RR intervals but is completely normal

82
Q

what is the precise method for finding HR

A 
PAPER SPEED (1500mm/min)
/
av RR interval in mm
83
Q

what is considered a normal HR

A

60-100

84
Q

what is bradycardia

A

low HR lower than 60

85
Q

what is tachycardia

h

A

high HR higher than 100

86
Q

if someone has an abnormal HR, what can that indicate

A

SA node arrythmia (dictates rhytm and rate)

87
Q

what is an exception for bradycardia

A

young, healthy maybe athletes,

\this low HR is normal

88
Q

what is the quick HR method

A

if the RR interval is…
5 large boxes = 60 bpm (brady)
4 large boxes = 75
3 large boxes = 100 bpm (tachy)

89
Q

explain how to assess P wave consistency

A

size/direction: make sure they are constant, upwards, and same distance from QRS
if abnormal = atrial arryhtmia (wandering ectopic pacemaker)

position: checking if the P waves are equidistance
if abnormal = av node arryhtmia

90
Q

knwo the procdure for measuring PR intervantl

A

.

91
Q

what is a normal PR interval time

A

120-200 ms

92
Q

what is an abnormal PR internal indicate

A

AV node arrythmia (too quick or too slow conduction)

93
Q

know the produceres forQRS complex duration

A

.

94
Q

what is a normal QRS complex duration

A

less than or equal 120 ms

95
Q

how to know the end of a QRS complex?

A

J poiint (corner, steepest return angle)

96
Q

what does an abnormal Qrs complex duration indicate

A

ventricular arythmia

97
Q

analysis for signs of hypertrophy always is measured on how many complexes

A

1 complex within same lead

98
Q

all arrythmia measurements are taken on the x or y axis

A

x

99
Q

all measurements for hypertrophy are taken on the y or x axis

A

y axis

100
Q

know the steps for measuring amplitudes

A

1) extend baseline
2) measure P, R wavese (from bse to high point)
3) measure Q and S waves (from pbase to low point)

101
Q

true or false: when reported amplidtude, there is directionality

A

yes (negative and postives)

102
Q

when measuring atrial hypertrophy, what leads are we observign

A

leads 2, 3 and AVF

103
Q

what is are normal p wave amplitudes

A

if the p waves in leads 2,3 and AVF are less than or equal to 0.3 mV

104
Q

hypertorphy is present in the atria if…

A

If the P wave amplitude is larger than 0.3 mV in either of Leads 2, 3, or AVF

105
Q

hypertrohpy is present in the left ventricle if…

A

If the R wave amplitude is larger than 1.4 mV in Lead 1,

If the R wave amplitude is larger than 1.2 mV in Lead AVL

106
Q

when measuring left ventricle hypertrophy, which leads do we look at

A

leads 1 and avL

107
Q

if there is abnormal values for atrial hypertrohy, what is a reason

A

atrial hypertrophy,

AV valves function abnormally (may be do to calcificaution)

108
Q

if there abnromal left ventricualr hyperpher, what could be a cause

A

systemic hypertension

109
Q

hypertrohpy is present in the right ventricle if.

A

If the R wave amplitude is larger than 0.5 mV in AVR.

AVR waves should be neg

110
Q

if we are assessing right ventricular hypertrohpy, what leads are we looking at

A

avr

111
Q

if there is abnormal values for right ventricular hypertorphy, waht is a cause

A

pulmonary hypertension

112
Q

when assessing signs of myocardial damage, where are observations made

A

e in the Lead with the LARGEST upward waves (i.e., the
same lead used in the 5-step analysis). Only one complex is analysed.

At least 2 of the listed 3 criteria are required to confirm myocardial damage

113
Q

what are the 3 steps to assessing signs of myocardial damage

A

1) look for St depression/elevation
2) look for t wave inversion
3) look at q/r ration

114
Q

know how to measure ST eleveation and depression

A

see notes

115
Q

what are some causes of ST segment changes

A
  • Ischemia - Ventricular hypertrophy
  • Infarction - Early repolarisation
  • Tachycardia - Pericarditis
  • Hypokalemia - Medications
116
Q

what are the 3 tissues in the heart that have their own inhreent rate of breathing

A 
SA node (72)
AV node (50)
Purkking (30)
117
Q

why does the SA node normally :drive the eheart”

A

beacuse it has the fastest inherent ratee

118
Q

explain heart block

A

However, the
ventricles can be observed beating at their inherent rate (i.e., 30 bpm) if there is a block in the normal
conduction pathway. In such a condition, the action potential ceases somewhere in its passage through
the heart

119
Q

what is a common place for heart block

A

AV node (since passage is normally slow)

120
Q

in a heart block , is interuption usually prolongued ?

A

the interruption of the depolarizing signal is not prolonged, as cells beyond the block develop their own pacemaker activity. In this example, either Purkinje fibers or ventricular tissue start contracting. It may take 5 to 30 sec for the tissue to “wake up”, but the heart will start beating at about 30 bpm until the normal conductive pathway is restored

121
Q

what are ectopic pacemakers

A

These are abnormal sites of spontaneous action potentials despite the presence of normal pacemaker signals and conduction pathways

122
Q

what is the cause of ectopic pacemakers

A

Ectopic pacemaker sites are often caused by a localized area of
damaged tissue that tends to produce extra action potentials and therefore extra, and often abnormal,
contractions. Depending on their origin and frequency, they may either be benign or quite dangerous.

123
Q

are ectopic pacemakers always dangerous

A

no they can be benign or dangerous depending on the origin and frequency

124
Q

what is the most serious type of arrythmia

A

fibrilation

125
Q

what are fibrillations

A

Fibrillation appears as random contractions and relaxations in the heart muscle

126
Q

why is the heart said to look like a bag of worms in fibrilation

A

beacuse of the writhing contractions

127
Q

when the benricles are fibrilation, what happens to pumping

A

there is no useful pumping

128
Q

what is fibrilation usually associated with

A

damaged myocardium due to poor blood supply (i.e., ischemia to the heart) resulting from a blockage of coronary arteries

129
Q

what happens to cardiac cells if thre is poor blood supply (like after heart attack)

A

s. If this occurs, cardiac cells will be in a poor metabolic state, leading to abnormal conduction properties. Conduction is likely to be slowed
or even blocked through some cells

130
Q

if Conduction is likely to be slowed or even blocked through some cells, what happens to the APS

A

This results in a random pattern of action potentials spreading
across the tissue rather than a regular wave of excitation

131
Q

fibrillation in the ventricles is not dangerous ?

A

false, it can cause death within minutes

132
Q

explain defibrillation

A

Defibrillation is sometimes possible by inducing an action potential in all cardiac cells simultaneously with a large electrical shock to the chest. Hopefully, after the cells repolarise, the SA node will depolarise first, as it should, and the normal pathway will be restored. Fibrillation in the atria is
not necessarily life threatening.

133
Q

how many signs must be present to solidify myocardial damage

A

2/3 signs

134
Q

explain ST depression/elevation

A

mark at j point and them 2mm
if there is an elevation/depression greateer than 1 mm
=abnormal (infarction, ishecmia etc)

135
Q

explain T wave inversion

A

T wave should be same direction as R wave wave

if not= damage to tissue

136
Q

explain Q/R ratio

A

normal ration between Q wave and R wave should be 0.25
if greater than 0.25
vector relationship has changed

259 - physiology (21 decks)

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