ECG Flashcards

(65 cards)

1
Q

What is P?

A

atrial depolarisation

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2
Q

What is the QRS complex? what does it mask?

A

ventricular depolarisation

masks atrial repolarization

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3
Q

What is the T wave?

A

ventricular repolarization

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4
Q

What does PR interval represent?

A

AV nodal delay

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5
Q

What is the ST segment ?

A

ventricular systole

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6
Q

What is the TP interval?

A

diastole

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7
Q

What does depolarization towards a recording electrode cause?

A

an upward deflection on ECG

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8
Q

What is an ECG line?

A

the imaginary line between two electrodes

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9
Q

How many electrodes are on a patient in a 12 lead ECG?

A

10 electrodes

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10
Q

What electrodes make up a 12 lead ECG?

A

6 chest electrodes (V1-V6)

4 limb electrodes

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11
Q
Where is 
a) V1
b) V2
c) V3
d) V4
e) V5
f) V6 
placed?
A

a) 4th intercostal, right of sternum
b) 4th intercostal, left of sternum
c) midway
d) 5th intercostal space, mid clavicular
e) 5th intercostal, anterior axillary line
f) 5th intercostal, mid axillary line

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12
Q

Which limb acts as an earth wire?

A

right leg

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13
Q

What is

a) lead I?
b) lead II?
c) lead III?

A

a) right arm to left arm
b) right arm to left leg
c) left arm to left leg

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14
Q

What are the 12 leads of an ecg?

A

3 bipolar limb leads ( I, II, III)
3 augmented unipolar limb leads (aVR, aVL, aVF)
6 unipolar chest leads

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15
Q

Which leads give a septal view of the heart?

A

V1, V2

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16
Q

Which leads give an inferior view of the heart?

A

II, III, aVF

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17
Q

Which leads give an anterior view of the heart?

A

V3, V4

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18
Q

Which leads give a lateral view of the heart?

A

I, aVL, V5, V6

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19
Q

In a normal cardiac axis, which leads are most positive?

A

I, II and III

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20
Q

In a normal cardiac axis, which leads are most negative?

A

aVR

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21
Q

In right axis deviation, which lead becomes negative and which becomes positive?

A

I becomes negative

aVF positive

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22
Q

In left axis deviation, which lead becomes negative and which becomes positive?

A

I becomes positive

aVF becomes negative

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23
Q

What causes right axis deviation?

A

right ventricular hypertrophy or tall individuals

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24
Q

What causes left axis deviation?

A

conduction abnormalities

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25
In an ECG what does a) 1 small square b) 1 large square represent?
a) 0.04 s | b) 0.2 s
26
What is 1 second on an ECG equal to?
5 big squares
27
What is 1 minute on an ECG equal to?
300 large squares
28
What are the steps in explaining an ECG?
* Name DOB * When it was taken * Calibration is * Electrical activity present * regular or irregular (look at space between QRS complexes) * heart rate is * P wave * Followed by QRS * PR interval is * QRS is * Rhythm is … sinus rhythm/sinus arrhythmia * Axis is …. * Comment on t wave and st one by one
29
How can a regular heart rate be calculated?
count number of large squares within one R-R interval and divide 300 by the number
30
How can an irregular heart rate be calculated?
the number of complexes on rhythm strip x6
31
Which 3 classifications of heart rhythm are there?
regular regularly irregular irregularly irregular
32
How can heart rhythm be determined?
mark out R-R intervals to see if they are the same
33
If you are suspicious of AV block, what would you do when considering heart rhythm?
map out both atrial and ventricular rhythms by looking at p waves and r waves
34
what might absent p waves and irregular rhythm suggest?
atrial fibrillation
35
What do you ask about p wave?
present and followed by QRS?
36
How long should be PR interval
3-5 small boxes | 0.12-0.2 seconds
37
What is a prolonged PR interval equal to ?
> 0.2s/ 5 small boxes
38
What does a prolonged PR interval indicate?
AV block
39
What is first degree heart block?
fixed, prolonged PR interval
40
What are the subtypes of second degree heart block?
Mobitz I and Mobitz II
41
What is Mobitz I heart block?
PR increases until QRS is dropped
42
What is Mobitz II heart block?
fixed, prolonged PR with dropped beats
43
What is third degree heart block?
p waves and QRS complexes are completely unrelated
44
How long should the QRS complex be?
0.12 seconds/ 3 small
45
Where does Mobitz I heart block occur?
in the AV node
46
Where does Mobitz II heart block occur?
after AV node in purkinje fibers or bundle of his
47
Where does first degree heart block occur?
in the atria between SA and AV node
48
What does a shortened PR interval indicate?
1. p wave originating closer to AV node as small atria or closer position of SA node 2. accessory pathway
49
What is a delta wave?
slurred upstroke of QRS complex | assoc. with Wolf-Parkinson-White syndrome
50
What does a narrow QRS complex indicate?
well conducted impulse resulting in well-organised ventricular depolarisation
51
What does a broad QRS complex indicate?
abnormal depolarisation sequence – for example, a ventricular ectopic
52
What do tall QRS complexes indicate?
ventricular hypertrophy
53
What are Q waves assoc with?
multiple Q waves in entire territory --> previous MI
54
When is ST elevation significant?
greater than 1 mm (1 small square) in 2 or more contiguous limb leads or >2mm in 2 or more chest leads.
55
What causes ST elevation?
acute full-thickness myocardial infarction
56
What does ST depression indicate?
≥ 0.5 mm in ≥ 2 contiguous leads indicates myocardial ischaemia
57
When are T waves considered tall?
> 5mm in the limb leads AND | > 10mm in the chest leads
58
What do tall T waves indicate?
hyperkalaemia | hyperacute STEMI
59
When are inverted T waves normal?
V1 | III
60
What are the causes of inverted T waves?
Ischaemia Bundle branch blocks (V4 – 6 in LBBB and V1 – V3 in RBBB) Pulmonary embolism Left ventricular hypertrophy (in the lateral leads) Hypertrophic cardiomyopathy (widespread) General illness
61
Wide QRS + fast rhythm would be what until proven otherwise?
ventricular tachycardia
62
An ECG showing ST elevation in leads V3 and V4, is most likely to be affecting which vessel?
anterior infart --> left anterior descending artery
63
An ECG showing ST elevation in leads II,III and aVF with greater in III than II, is most likely to be affecting which vessel?
right coronary artery
64
An ECG showing ST elevation in leads II,III and aVF with greater in II than III, is most likely to be affecting which vessel?
circumflex artery
65
In acute MI, are tall t waves or ST elevation seen first?
t waves