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BPK 305 > ECG > Flashcards

ECG Flashcards

1
Q

ECG

A

measures dynamic changes in membrane potential

recording of small extracellular signals produced by movement of APs through cardiac myocytes

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2
Q

ECG measures movement of positive charge

A

propagating depolarization

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3
Q

upwards deflection

A

depolarization moving towards the electrode

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4
Q

downwards deflection

A

depolarization away from the electrode

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5
Q

repolarization

A

toward the electrode

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6
Q

lead

A

difference in voltage

each lead looks at the heart from a unique angle and plane

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7
Q

bipolar leads

A

3 bipolar limb leads

looks at heart in vertical plane

einthoven’s triangle

body is an electrical “volume conductor”

output: voltage difference provides a direct representation of heart’s electrical activity in that lead

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8
Q

unipolar leads

A

3 augmented voltage limb leads

6 precordial or chest leads

measures the electrical potential at one electrode relative to a reference point (often a central terminal)

augmented voltage

circle of axes and einthoven’s triangle

have no negative pole

output: each lead records the potential at one electrode compared to a calculated average of the other two limb electrodes

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9
Q

standard bipolar leads

A

lead 1: RA- to LA +
lead 2: RA- to LL+ (views conducting system)
lead 3: LA- to LL+

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10
Q

einthoven’s law

A

lead 1+lead 3= lead 2 (like vectors)

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11
Q

advantages of ECG

A

simple and cheap

info about:
- anatomical orientation of heart
- chamber sizes
- arrhythmias and conduction blocks (is heart conducting normally)
- myocardial ischaemia (is heart getting enough blood)
- myocardial infarction
- congenital defects (abnormalities)
- changes in cardiac function with time/therapy

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12
Q

standard unipolar leads

A

aVR: RA +ve, (LA+LL) -ve
aVL: LA +ve, (RA+LL) -ve
aVF: LL +ve, (LA+RA) -ve

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13
Q

depolarization away from lead

A

negative deflection

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14
Q

depolarization toward lead

A

positive deflection

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15
Q

repolarization away from lead

A

positive deflection

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16
Q

repolarization towards lead

A

negative deflection

17
Q

chest leads unipolar “precordial”

A

view heard from horizontal plane

provides a view of the hearts electrical activity from a horizontal plane

provides info about specific areas of heard - good for diagnosing cardiac conditions

takes average of the three limb electrodes

18
Q

standard chest leads

A

add
V1 and V2 = septal
V3 and V4 = anterior
V5 and V6 = lateral

subtract
take average mean (1,2,3) = center of heart

19
Q

frontal plane leads

A

lead 1,2,3
aVL,aVR,aVF

20
Q

transverse plane leads

A

V1-V6

21
Q

what does each type of leads show us

A

scalar (1D) projection in that plane of the 3-D vector

12 leads allow us to reconstruct the amplitude and direction of this vector

22
Q

right axis deviation

A

RV hypertrophy
infants
tall and thin
left posterior hemiblock

23
Q

left axis deviation

A

obesity
pregnancy
left anterior hemiblock
LV hypertrophy

24
Q

extreme axis

A

dextrocardia
cardiac pacemaker

25
Q

sinus rhythm

A

normal heart rhythm

HR driven by SA node

depolarization along normal conduction path

subtle changes in HR occurs with each respiratory cycle (inspiration accelerated HR, expiration slows) - deepining of respirations accelerates these changes

loss of this rhythm may be seen in diabetes

26
Q

types of altered sinus

A

mechanisms that vary the firing frequency of the cardiac pacemaker cells

pp interval is altered

bradycardia
Tachycardia
respiratory sinus arrythmia

27
Q

tachycardia

A

increases HR

27
Q

bradycardia

A

decreases HR

28
Q

respiratory sinus arrythmia

A

breathing changes alters vagus nerve output

29
Q

atrioventricular conduction blocks

A

block between AVN and perkinji fibres

30
Q

premature depolarizations

A

extrasystoles - coupled to normal AP, re-entrant pathway, comes out of no where

occurs occasionally in most normal individuals - common in certain abnormal conditions

31
Q

ectopic tachycardias

A

sporadic

ectopic pacemaker

AP in a re-entry loop

begins and ends abruptly, could be a few beats or for hours, days ( and they often reoccur)

happens in ventricles, but more commonly in atria

32
Q

fibrillation

A

real trouble

atrial or ventricular - jiggles (not pumping)

multiple re-entry loops

uncoordinated contraction - insufficient pumping of blood

irregular type of contractions is inefficient in propelling blood

probably represents a re-entry phenomenon

not pumping blood to the rest of the body

33
Q

right bundle branch block

A

no organized ventricle repolarizing

wide QS

slurred S in lateral leads

altered T in septal leads

34
Q

acute anterior infarction

A

in front of heart tissue blocked

increased ST in V1-6, 1 and aVL

reciprocal ST depression in 2,3 and aVF

standing different in resting potential

BPK 305 (5 decks)

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