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Semester 2-CVS > Session 6-ECG > Flashcards

Session 6-ECG Flashcards

1
Q

True or false: ventricular depolarisation from epicardium to endocardium enables coordinated contraction of atria and ventricles

A

FALSE - depolarisation from endocardium to epicardium

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2
Q

What is the name of the rhythm that the SA node sets?

A

Sinus rhythm

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3
Q

Where is the AV node located?

A

In the inter-atrial septum, above the tricuspid valve

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4
Q

What is the AV node continuous with?

A

Bundle of His

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5
Q

True or false: the bundle of His is the only conducting path from atria to ventricles

A

TRUE

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6
Q

What separates the atria and ventricles?

A

Fibrous ring

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7
Q

What do the Purkinje fibres do?

A

Rapid spread of depolarisation throughout ventricular myocardium

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8
Q

Which area of the heart is the last to be depolarised?

A

Base of the ventricles

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9
Q

What does ECG record and how does it do this?

A

Changes on extracellular surface of cardiac myocytes during wave of depolarisation and repolarisation from surface of the body using electrodes pasted on the skin

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10
Q

What does a depolarisation wave going towards a positive electrode look like on an ECG?

A

Positive (upright)

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11
Q

What does a depolarisation wave going towards the negative electrode look like on an ECG?

A

Negative (upside down)

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12
Q

What does a repolarisation wave going towards the positive electrode look like on an ECG?

A

Negative (upside down)

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13
Q

What does a repolarisation wave going towards the negative electrode look like on an ECG?

A

Positive (upright)

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14
Q

What is the first electrical event, forming the horizontal line at the start of the P wave?

A

SA node depolarisation

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15
Q

Where does atrial depolarisation spread?

A

Along muscle fibres and internodal pathways and spreads through right and left atria

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16
Q

What is the direction of atrial depolarisation?

A

Downwards and to the left towards AV node

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17
Q

Which event results in the p wave?

A

Atrial depolarisation

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18
Q

Why is there a delay at the AV node?

A

Allows time for atrial contraction to fill ventricle

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19
Q

How is the delay at the AV node shown on the ECG?

A

Flat line after p wave

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20
Q

In which direction does the septum depolarise?

A

From left to right

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21
Q

What is the q wave?

A

Depolarisation of interventricular septum, producing small downward deflection

22
Q

What is the R wave?

A

Depolarisation of apex and free ventricular wall, producing large upward deflection

23
Q

Why is the R wave large?

A

Large muscle mass-more electrical activity

24
Q

What happens to the R wave of the left ventricle hypertrophies?

A

Will be correspondingly taller

25
Q

What is the S wave?

A

Depolarisation spreading upwards to base of ventricles, producing small downward deflection

26
Q

Why is the S wave small and downward?

A

Downward because moving away from electrode

Small because not moving directly away

27
Q

Where does ventricular repolarisation begin?

A

On epicardial surface

28
Q

What is the T wave?

A

Medium upward deflection caused by ventricular repolarisation

29
Q

What is the P wave?

A

Atrial depolarisation

30
Q

What is QRS wave?

A

Ventricular depolarisation

31
Q

How many electrodes are used in an ECG?

A

10 electrodes - 4 on the limbs and 6 on the chest

32
Q

How many leads does an ECG produce?

A

12

33
Q

How many leads are there in the vertical plane?

A

6 (limb leads)

34
Q

Which limb leads are looking at the inferior surface of the heart?

A

Leads II, III and aVF

35
Q

Which leads are looking at the left side of the heart?

A

Leads I and aVL

36
Q

Where do chest leads V1 and V2 face?

A

Right ventricle and septum

37
Q

Where do chest leads V3 and V4 face?

A

Apex and anterior wall of ventricles

38
Q

Where do chest leads V5 and V6 face?

A

Left ventricle

39
Q

What is the normal speed of ECG paper?

A

25mm/second

40
Q

How many small squares and how many large squares does the ECG get through per second?

A

25 small squares

5 large squares

41
Q

How many large squares in 1 minute?

A

300 large squares

42
Q

What counts as 1 heart beat on an ECG?

A

Each PQRST complex (start of P wave to start of next P) = 1 cardiac cycle

43
Q

Which interval is used to calculate heart rate on an ECG?

A

R-R interval

44
Q

How is heart rate calculated if the rhythm is irregular?

A

Count the number of QRS complexes in 6 seconds then multiply by 10

45
Q

What is the normal PR internal?

A

3-5 small boxes

46
Q

When is PR interval prolonged?

A

If >1 large box

47
Q

Where is PR interval measured from and to?

A

From start of P wave to end of horizontal line

48
Q

What is the normal QRS interval?

A

<3 small boxes

49
Q

Why is there sometimes slight variation in sinus rhythm?

A

Respiration

50
Q

Which parts of an ECG are checked to make sure a patient has normal sinus rhythm? (5)

A

1) heart rate (60-100bpm)
2) presence of p waves, followed by QRS
3) normal PR interval
4) normal QRS width
5) QRS preceded by p wave

51
Q

What is a sinus rhythm with rate <60bpm called?

A

Sinus bradycardia

52
Q

What is a sinus rhythm with rate >100bpm called?

A

Sinus tachycardia

Semester 2-CVS (18 decks)

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