ECG Flashcards

1
Q

the general line of ECG

A
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2
Q

ECG stands for

A

electrocardiogram

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3
Q

P wave

A

atrial depolarization

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4
Q

QRS complex

A

ventricular depolarization (contracting)

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5
Q

T wave

A

ventricular repolarization (ventricles relax)

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6
Q

where is atrial repolarization?

A

with QRS complex (covered)

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7
Q

define ECG

A

assesses the NET cardiac electrical activity measured between two points on the body’s surface

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8
Q

ECG: Cell-to-cell propagation of cardiac AP occur because of the ability of _______ to provide extremely efficient electrical connectivity between cardiac muscle cells that allow them to beat in a functional _________

A

Cell-to-cell propagation of cardiac AP occur because of the ability of GAP JUNCTIONS to provide extremely efficient electrical connectivity between cardiac muscle cells that allow them to beat in a functional SYNCYNCTIUM

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9
Q

ECG is the primary clinical tool for the diagnosis of: 2

A

— cardiac arrhythmias (abnormal electrical patterns in the heart)
— myocardial injuries that cause disturbances in heart rate (HR), rhythm, and/or wave-front propagation

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10
Q

ECG: strength of cardiac muscle contraction is _____ _______ to the intracellular Ca2+ concentration

A

directly proportional

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11
Q

ECG: after action potential, ________ Ca2+ channels opening causing a 1000-fold rise in the intracellular free Ca2+

A

L-type slow Ca2+ channels

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12
Q

ECG: sliding filament theory

A
  • Depolarization conducts along membrane to T- tubules
  • Calcium influx induces more Ca2+ release from the SR stores into intracellular fluid
  • Ca2+ binds with troponin causing shift to reveals the binding site for myosin heads
  • Cross-bridge formation between the actin and myosin filaments of the sarcomere
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13
Q

study heart (no question)

A
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14
Q

Trace blood flow from SVC/IVC (in words)

A
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15
Q

Order of Valves opening in heart: Tiny Penguins Marching Along

A

tricuspid, pulmonary, mitral, aortic

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16
Q

normal blood pressure

A

systolic: <120
diastolic: <80

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17
Q

elevated blood pressure

A

systolic: 120-129
diastolic: <80

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18
Q

High blood pressure (hypertension) Stage 1

A

systolic: 130-139
diastolic: 80-89

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19
Q

High blood pressure (hypertension) Stage 2

A

systolic: >140
diastolic: >90

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20
Q

Hypertensive crisis

A

systolic: >180
diastolic: >120

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21
Q

ECG: systole

A

during ventricular contraction to pump blood flow

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22
Q

ECG: diastole

A

occurs after contraction when the heart relaxes (ventricles fill with blood)

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23
Q

study

A
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24
Q

ECG: “lub”

A

S1
First heart sound “Lub, dub”
Closure of the tricuspid and mitral valves
Beginning of ventricular systole (ventricular contraction)

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25
Q

ECG: “dub”

A

S2
Second heart sound “lub, dub”
Closure of the aortic and pulmonary valves
beginning of ventricular diastole

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26
Q

ECG: heart cells

A

Pacemaker cells:
- SA node
- AV node
- His bundle
- Bundle branches
- Purkinjie fibers

working myocardial cells

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27
Q

ECG: what do pacemaker cells do in the heart?

A

responsible for the initiation & conduction of electrical signaling through the heart

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28
Q

ECG: electrical conduction sequence

A

SA node
Atria
AV node
His bundle
Bundle branches
Purkinjie fibers
Ventricles

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29
Q

ECG: what is the fastest conduction cell?

A

SA node

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30
Q

ECG: what does the AV node do?

A

create a slight delay between atrial contraction and ventricular contraction

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31
Q

ECG: what do Purkinje fibers do?

A

ensure that all ventricular cells contract at nearly the same instant (rapid conduction)

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32
Q

ECG: what cell is the Heart Rate (HR) normally controlled by?

A

SA nodal cells

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33
Q

ECG: Automaticity

A

property of the specialized cardiac cells to
spontaneously fire APs

o SA node has fastest rate (dominant pacemaker)
o Sinoatrial rhythm is 60-100 bpm
o latent pacemakers (all other cells)

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34
Q

ECG: what is the AV rhythm range

A

Atrioventricular (AV) rhythm is only 40-60 beats per minute.

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35
Q

ECG: five phases of AP in Myocardium

A

Phase 0: upstroke, rapid depolarization
Phase 1: rapid repolarization following the peak (hidden)
Phase 2: depolarized plateau
Phase 3: rapid repolarization following the plateau
Phase 4: a.k.a., resting potential, which can be stable or unstable

36
Q

ECG: what stage of the Action potential graph is unstable in slow-response (pacemaker)?

A

phase 4: resting potential (slowly repolarizing)

Pacemaker cells set the pace

37
Q

ECG: fast-response VS slow-response AP graphs

A
38
Q

ECG: in cardiomyocytes, the fast influx of Na+ causes very rapid/short-lived phase ___

A

phase 0

*stable phase 4

39
Q

ECG: what does the AP graph look like for cardiomyocytes?

A

fast-response

40
Q

ECG: what does the AP graph look like for pacemaker cells?

A

slow-response

41
Q

ECG: in pacemaker cells, during phase 0 the ____ influx of Ca2+ causes a slow Na+ influx

A

slow????????

Phase 4 is depolarising due to slow influx of Na+

42
Q

ECG: in both fast/slow-response APs, repolarization (phase 3) due to the return of ____ permeability

A

K+

43
Q

ECG: what is RP

A

refractory periods

Refractory periods in cardiac muscle allow complete emptying of the ventricle prior to the next contraction

44
Q

ECG: during absolute RP, the working myocardial cells can/cannot be stimulated to fire another action potential

A

cannot

*Coincides with systole (contraction) to prevent summated contractions (tetanus) from occurring in the heart

45
Q

ECG: during relative RP, the excitability recovers to ____ values

A

normal values

*Coincides with the period of rapid repolarization following plateau

46
Q

ECG: CO

A

cardiac output

blood volume pumped by the heart per unit time

~5.6 L/min

47
Q

ECG: CO=

A

CO = Stroke Volume (SV) x Heart rate (HR)

48
Q

ECG: SV?

A

Stroke Volume

volume of blood pumped out of one ventricle of the heart in a single beat; May be calculated as End diastolic volume – End systolic volume (~70-80 mL)

49
Q

ECG: TPR?

A

Total Peripheral Resistance

Blood pressure = CO x TPR

50
Q

ECG: homeostatic control of the heart

A
51
Q

ECG: blood pressure can be maintain by altering either the ____ and/or ____

A

CO and/or TPR

52
Q

ECG: Bainbridge reflex and baroreceptor reflex

A

feedback mechanisms to homeostatically regulate HR

53
Q

ECG: what is normal sinus rhythm?

A

when the sinoatrial Node (SA) node is pacemaker, the Normal Heart Rate (HR) should be between 60-100 beats/min.

Trachycardia: >100 beats/m
Bradycardia: <60 beats/m

54
Q

Tachycardia vs Bradycardia

A

Tachycardia: >100 beats/m
Bradycardia: <60 beats/m

55
Q

ECG: lead

A

the electrical potential difference between 2 electrodes

56
Q

just study

A
57
Q

ECG: waves and events

A
58
Q

ECG: what intervals/segments are isoelectric?

A

PR interval
ST segment

59
Q

ECG: physiological events (8)

A
60
Q

ECG: when does SA node fire on an ECG?

A
61
Q

when does the AV node pause on the ECG graph?

A
62
Q

when do the ventricles squeeze on the ECG graph?

A
63
Q

when do the ventricles relax on the ECG graph?

A
64
Q

ECG: what is the only electrical link between the atria and the ventricles?

A

AV node

65
Q

ECG: what does the AV node electrically link?

A

atria and ventricles

66
Q

ECG: where is atrial depolarisation, ventricular depolarization, and ventricular repolarization on the ECG graph?

A
67
Q

ECG: is the ST segment isoelectric?

A

yes

68
Q

What’s wrong with B?

A

PR interval is too long (normally 0.12-0.2 seconds)

A long PR interval might indicate something wrong with the AV node

69
Q

what’s wrong with B?

A

Split R wave (R wave represents depolarization of the ventricles)

A split R wave may indicate damaged or undernourished bundle branches (due to poor blood supply and one of the ventricles depolarizing later)

70
Q

What’s wrong with B?

A

Exaggerated/long QRS

QRS represents the rapid depolarization of the ventricles

A long QRS may indicate Purkinje fibers are damaged or poorly supplied with blood

this causes slow depolarization of ventricles

*long Q: heart attack may have occurred

71
Q

ECG: If the pair of electrodes is oriented _____ to the dipole, the recorded potential difference (voltage difference) will be maximal.

A

parallel

In other words, if the positive recording electrode faces a wave of depolarization, it will record an upward signal.

72
Q

ECG: how do you calculate HR?

A

HR = 60/R-R interval

73
Q

ECG: where are leads I, II, III on body?

A
74
Q

ECG: charge of electrodes Leads I-III

A
  • Lead I: (-) electrode on RA and (+) electrode on LA
  • Lead II: (-) electrode on RA and (+) electrode on LL
  • Lead III: (-) electrode on LA and (+) electrode on LL
75
Q

ECG: Einthoven’s Law

A

Dipole calculation

Lead I + Lead III = Lead II

76
Q

ECG: Einthoven’s Law- calculate Lead II using I and II

A
  • +R
    • Q,S

Lead II = I + III
II = ((+6-3)+(+12-4))
II = 3 + 8
II = 11

77
Q

ECG: indicators of normal Sinus ECG

A
  1. QRS complex occur app. 1 per second
  2. QRS complex: when R wave is upright in Lead II with a duration is <120 ms
  3. QRS is preceded by only one P wave
  4. QT interval is less than half the R-R interval
  5. no extra P waves
78
Q

when reading an ECG, ask yourself?

A
79
Q

ECG: Atrial Fibrillation

A

irregular heart rhythm
no clear P waves
can cause clots in the atrium –emboli
Tx: anticoagulant therapy

80
Q

ECG: Third-degree (complete) AV block

A

Normal P waves
R waves irregular (dropped QRS complex)
Needs pacemaker- atria and ventricles contracting at own rates

81
Q

examples of ventricular arrhythmias

A
82
Q

ECG: Long QT syndrome

A

the electrical system in ventricles is taking longer to recover/recharge between beats

leads to — ventricular tachycardia

83
Q

ventricular tachycardia

A

ventricles beat too fast
wide QRS complex

84
Q

Torsade de pointes

A

starts with Long QT syndrome and progresses

High risk of sudden cardiac death if sustained

rapidly degenerates into ventricular fibrillation and hemodynamic collapse

85
Q

AV valves
Semilunar valves

A

AV valves:
Tricuspid
Mitral (bicuspid)

Semilunar valves:
Aortic
Pulmonary

86
Q

calculate the HR

A

HR = 60/R+R

4(0.2) + 3(0.04) = 0.92
HR = 60/0.92
HR = 65 BPM