Intro to ECG Flashcards

1
Q

What is SLLI?

A

Standard limb lead 1 - left arm right arm

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2
Q

What is SLLII?

A

Standard limb lead 2 - left leg wrt right arm

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3
Q

What is SLLIII?

A

Standard limb lead 3 - left leg wrt left arm

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4
Q

What plane do SLL look at events in?

A

Frontal plane

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5
Q

A wave of depolarisation moving from left leg to right arm will show what sort of blip on a SLL II ECG?

A

Negative

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6
Q

A wave of depolarisation moving from right arm to left leg will show what sort of blip on a SLL II ECG?

A

A positive blip - as it travels in the same wave of depolarisation

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7
Q

A wave of repolarisation moving from the left leg to the right arm will show what on a SLL II ECG?

A

A positive blip

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8
Q

A wave of repolarisation moving from the right arm to the left leg will show what on a SLL II ECG?

A

Negative

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9
Q

What does each wave on ECG correspond for?

A

P - atrial depolarisation
QRS - ventricle contraction
T - ventricle repolarisation

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10
Q

Where does the main wave of depolarisation travel to?

A

Down the atria, ventricles and through the body fluids to the electrode of the left leg (SLLII)

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11
Q

What is the PR interval and how long should it last?

A

Time from atrial depolarisation to ventricular depolarisation (transmission through AV node)
0.12-0.2s

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12
Q

What is the QRS and how long should it last?

A

Time for ventricular depolarisation <0.12s (~0.08s)

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13
Q

What is the QT interval and how long should it last?

A

Time for ventricular depolarisation and depolarisation

0.42s

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14
Q

Why isn’t atrial depolarisation recorded on the ECG?

A

As it coincides with ventricular depolarisation and as it involves much more tissue depolarising much faster, it overpowers signal from atrial depolarisation

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15
Q

What events are transmitted better on an ECG?

A

Faster events

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16
Q

What are the different events that occurs in the QRS complex?

A

Q - IV septum depolarises L to R
R - depolarisation from endocardial to epicardial surface
S - the upper part of the IV septum depolarises

17
Q

Why are Q and S wave negative in the QRS complex?

A

Negative as they travel away from main vector of depolarisation - go towards to right arm

18
Q

Why is the T wave a positive blip?

A

The AP is longer in endocardial cells than in epicardial cells, so the wave of depolarisation runs in the opposite direction of wave of depolarisation

19
Q

Why is the R wave (QRS) in SLL II larger than the two other SLL?

A

As the main vector of depolarisation is inline with the axis of recording from the left leg wrt the right arm

20
Q

What would happen if heart was rotated to left or develop L hypertrophy or R atrophy?

A

Causes axis deviation - so blip in SLL I will be larger than the blips in SLL II and III, which will be smaller

21
Q

What extra information do the augmented limb lead give you?

A

By recording from one limb lead wrt to the two combined, it gives you 3 other perspectives on events in the heart

22
Q

What are the augmented limb leads?

A

aVR
aVL
aVF

23
Q

What is aVR?

A

R arm wrt the left arm and left leg (SLL III)

24
Q

What is aVL?

A

L arm wrt the left leg and right arm (SLL II)

25
Q

What is aVF?

A

L leg wrt the left and right arm (SLL I)

26
Q

Why is the R wave (QRS) negative in aVR?

A

Travels in opposite direction to main vector of depolarisation

27
Q

Why is the R wave (QRS) the smallest blip in aVL compared to all of the augmented and standard limb leads?

A

Travels at a right angle to the main vector of depolarisation

28
Q

What plane do the precordial (chest) leads look at events in?

A

Transverse plane

29
Q

What extra information do the precordial leads provide?

A

They’re arranged in front of the heart and therefore look at the same events, but in the transverse plane

30
Q

Explain the concept of progression in the precordial leads

A

It is the change in the R waves from V1 to V6 - a negative blip is recorded in V1, a positive blip in V6 and a flip over somewhere around V3/4

31
Q

What can the rhythm strip tell you?

A

Heart rate - count R waves in 30 large square and multiply by 10

32
Q

How fast does an ECG run?

A

25mm/sec

33
Q

How long is the calibrating pulse and how many squares does it take up?

A

0.2s = 1 large square (5mm)

34
Q

What are the boundaries for normal HR and abnormal?

A

60-100 normal
> 100 tachycardia
< 60 bradycardia

35
Q

What to look out for on the rhythm strip

A

Is QRS followed by P wave?
Is PR too short (<0.12s) or too long (>0.2s)?
Is QRS too long (>0.12s?
Is the QT too long (>0.42s at 60bpm)?

36
Q

What does STEMI stand for?

A

ST elevated myocardial infarction

37
Q

What does NSTEMI stand for?

A

Non-ST elevated myocardial infarction

38
Q

Is STEMI or NSTEM worse?

A

STEMI is worse