electrocardiography/reading ecg Flashcards

1
Q

is the sa node acted on by other cells

A

no

Spontaneously active cells

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2
Q

what is the p wave

A

Conducts current down atria & internodal pathways

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3
Q

function of av node

A

Current slows down more time for atrial muscle contraction

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4
Q

how does current travel down the septum

A

His-Purkinje system

Rapid conduction through left & right bundles -> Purkinje fibres -> ventricular contraction

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5
Q

how is that complex shown on an ecg

A

QRS complex of ECG

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6
Q

what is the t wave

A

Cardiac muscle relaxes & membrane potential recovers/repolarises
T-wave of ECG

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7
Q

what does lead II read

A

electrical currents from right shoulder to left leg

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8
Q

which lead would have the largest current (biggest deflection of the qrs)

A

lead II
Electrical current flowing away from the positive electrode results in a negative (downward) waveform display. In Lead II, the R wave is therefore positive. … The closer the mean QRS axis is to the electrical axis of Lead II, the larger the amplitude of the R wave.

qrs is going the exact same direction as the positive component of lead 2

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9
Q

how would the qrs change if lead II wasn’t perfectly parallel with the direction of the current

A

a lower qrs

less deflection in qrs as not parralell

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10
Q

what is axis deviation

A
  • change in heart position
  • change in position of electrical conduction ( one of the right or left bundle branches can de damaged or one more dominant that the other- current goes in a different direction)
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11
Q

where does lead 1 measure

A

horizontal

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12
Q

ii

A

right shouled to left lef

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13
Q

iii

A

left shoulder to right leg

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14
Q

aVF

A

down the middle

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15
Q

aVR

A

right leg to left shoulder

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16
Q

how would the p wave chnage if a pacemaker is producing currents in mixed directions

A

absent p wave

lots of small signal drown our the larger signal to av node

17
Q

what is this condition known as

A

Atrial fibrillation - loss of p-wave

18
Q

what is Atrial flutter

A
  • saw-tooth pattern
19
Q

what would happen if we had a barrier or problem at the av node

A
  • longer pr interval
    Type I Heart Block
    Type II Heart Block
20
Q

from what 2 points is the qr interval measured from

A

from start of p to start of q not R

21
Q

what is a type 1 heartblock

A

delay in conduction
calcium channel heart block
increase p r interval duration

22
Q

what is type 2

and cause

A

loss of conduction
more of an actual block
missing qrs complex ans thus t
due to damage to cells or drugs

23
Q

what is the Wolff-Parkinson-White

A

is caused by an extra electrical pathway in the heart. This allows electrical signals to bypass the usual electrical system route and form a short circuit, resulting in an abnormally fast heart rhythm.
accessory pathway

24
Q

what is it shown on an ecg

A

shorter pr complex
pre excitation
biphasic t wave

25
what causes a biphasic t wave
currents are going thru faster | alight depolarisation due to accessory pathway
26
what causes pre excitation
accessory pathway allows the current to get from atria to ventrciles faster
27
what is the bottom graph in the ecg
rythm strip | so one lead shown for a longer period of time normally lead ii
28
what atrcuture do you use to read ecgs
rate ryhthm and axis
29
what is the rate
r r interval
30
how to work it out
300/ number of large swuares e.g. 3,3
31
what is the rhythm
p r interval qrs duration st segment
32
what is the st segment
the straight part from s to t
33
how do you work them out
each small square is 40ms
34
how do you work out axis
guestimate using the diagram
35
what is the point of multiple leads
greater resalution | more detail abouts whats going on