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Cardio > ECG > Flashcards

ECG Flashcards

1
Q

what is an ECG

A

a recording of potential charges, detected by electrodes positioned on the body surface, that allows the electrical activity of the heart to be monitored in a simple and non invasive manner

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2
Q

what is a 12 lead ECG comprised of

A

three standard limb leads, three augmented voltage (aV) leads and six chest leads

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3
Q

What are standard limb leads also termed

A

bipolar

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4
Q

what are the names of the three standard limb leads?

A

I, II and III

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5
Q

what are the names of the three aV leads?

A

aVL, aVR and aVF

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6
Q

what are the names of the six chest leads?

A

V1-V6

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7
Q

what are augmented voltage leads also termed?

A

unipolar

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8
Q

what are chest leads also known as

A

precordial leads

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9
Q

Why use 12 leads instead of just 1?

A

12 leads allows you to determinet he axis of the heart, look for any ST segment or T wave changes in relation to specific regions of the heart and look for any voltage criteria changes

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10
Q

which leads allow a vertical view and which leads allow a horizontal view?

A

veritcal view- standard limb leads and aV leads horizontal- chest leads

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11
Q

How does limb lead I connect?

A

Either it connects from the negatively charged right arm to the positively charged left arm or it connects from the negatively charged right shoulder to the positively charged right left shoulder

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12
Q

How does limb lead II connect?

A

Either it connects from the negative charger right arm to the positively charged left leg or it connects from the negatively charged right shoulder to the positively charged groin

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13
Q

How does limb lead III connect?

A

either it connects from the negatively charged left arm to the positively charged left leg or it connects from the negatively charged left shoulder to the positively charged groin

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14
Q

what is it called when the limb leads form a triangle around the heart?

A

Einthoven’s triangle

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15
Q

which limb lead passes through the heart inferiorly?

A

Limb lead II

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16
Q

why is the P wave shaped how it is?

A

Because the SA node is located at the top right of the heart and so atrial depolarisation occurs from the top right of the heart and moves down and to the left following the same direction of neg to pos of limb lead II causing a small upward deflection

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17
Q

how long should a P wave last?

A

0.12 s or less

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18
Q

what does the P wave represent

A

atrial depolarisation

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19
Q

why is the Q wave shaped how it is?

A

because the AV node is located in the interventricular septum meaning that depolarisation starts in the interventricular septum and spreads down from left to right instead of following the neg to pos direction of limb lead II, causing a small negative deflection on the ECG

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20
Q

how long does the QRS complex usually last?

A

0.1 s or less

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21
Q

Why is the R wave shaped how it is?

A

because the free walls of the ventricles are depolarised downwards from right to left , following the direction of the neg to pos direction of limb lead II, causing a positive upwards deflection on the ECG

22
Q

why is the S wave shaped how it is shaped?

A

because the base of the ventricles are depolarised upward from left to right going against the direction of the neg to pos limb lead II, causing a small negative deflection in the ECG

23
Q

what does the T wave respresent?

A

ventricular repolarisation

24
Q

why is the T wave shaped the way it is?

A

repolarisation is negative and the ventricle is repolarised from the positive to the negative end of limb lead II, the negative moving in the negative direction is the same as a positive moving in a positive direction and so the T wave appears as a small positive deflection on the ECG

25
Q

What does the PR interval represent?

A

the time taken for the electrical impulses to reach the ventricles from the SA node

26
Q

how long is the PR interval usually?

A

0.12-0.2s

27
Q

when does the PR interval start and end on an ECG?

A

it starts at the start of the P wave and ends at the start of the QRS complex

28
Q

What influences the PR interval time?

A

time taken for action potential to pass through AV node and bundle of HIS fibres

29
Q

Where is the ST segment on an ECG?

A

from the start of the QRS complex to the end of the T wave

30
Q

what does the ST segment normally look like and why?

A

it is normally a flat line because the ventricles are fully depolarised and there is no real large changes going on (plateau phase 2)

31
Q

what will the ST segment look like during pathological changes?

A

the ST segment will not be on the isoelectric line, there may be ST depression or elevation

32
Q

where is the QT interval seen on an ECG

A

from the start of the QRS complex to the end of the T wave

33
Q

what does the QT interval represent?

A

this represents the time taken for ventricle depolarisation and repolarisation

34
Q

how long should the QT interval be?

A

0.44s in males and 0.46s in females

35
Q

what does prolongation of the QT interval suggest?

A

disturbances of cardiac rhythm, which may be due to drugs patient is on

36
Q

what is it called when there are six different views of the heart when the frontal leads are put together?

A

the hexaxial reference system

37
Q

what do aV leads allow you to see?

A

the heart from different angles than the standard limb leads

38
Q

why do the waves appear upside down for aVRv lead?

A

because during depolarisation means the electrical conduction is moving away from its recording electrode

39
Q

what are the lateral limb leads and why?

A

aVL and lead I because they both have a recording electrode on the left arm, giving a view of the heart from a lateral view

40
Q

what are the inferior limb leads and why?

A

aVF, lead II and lead III because they all have a recording electrode on the left foot, giving a view of the heart from an inferior direction

41
Q

what happens to the R and S waves as you go from V1-V6

A

R wave increases and S wave decreases

42
Q

where is V1 positioned

A

at the fourth intercostal space immediately right of the sternum

43
Q

where is V2 positioned

A

at the fourth intercostal space immediately left of the sternum

44
Q

where is V3 positioned

A

mid way between V2 and V4

45
Q

where is V4 positioned

A

at the fifth intercostal space at the mid clavicular line

46
Q

where is V5 positioned

A

same horizontal level as V4 anterior axillary line

47
Q

Where is V6 positioned

A

same horizontal level as V4 mid axillary line

48
Q

how many sticky pads are used for 12 lead ECG

A

10

49
Q

where are the sticky pads that aren’t V1-V6 placed?

A

on the four limbs

50
Q

which lead is usually the rhythm strip

A

lead II

Cardio (38 decks)

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