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Cardiovascular system SA > First look at an ECG > Flashcards

First look at an ECG Flashcards

1
Q

Where is the different standard leg limbs measured from

A

SLL I = left arm wrt right arm
SLL II = left leg wrt right arm
SLL III = left leg wrt left arm

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2
Q

In an ECG what does the P wave correspond to

A

atrial depolarisation

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3
Q

In an ECG what does the QRS complex correspond to

A

ventricular depolarisation

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4
Q

In an ECG what does the T wave correspond to

A

Ventricular re-polorisation

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5
Q

A wave of approaching depolarisation cause what on an ECG

A

an upward Blip

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6
Q

What events record better on an ECG

A

Fast events

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7
Q

What does an ECG look for

A

Look for disorders of rhythms or conduction

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8
Q

What is examples of disorder or rhythms of conduction

A

atrial flutter, atrial fibrillation,

ventricular fibrillation

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9
Q

What is the action of a defibrillator

A

puts all cells into refractory period so that they can restart conduction

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10
Q

A typical ECG shows what limb lead

A

Standard limb lead II recording from the left leg (+) with respect to the right arm (-)

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11
Q

If a wave of depolarisation moves towards left leg(+) what outcome does this show on the ECG

A

Positive blip

as creates a positive potential in relation to the arm

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12
Q

If a wave of depolarisation moves towards the right arm (-) what is the outcome on the ECG

A

Negative blip

as a positive wave is moving towards the negativity of the arm = negative potential

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13
Q

If a wave of re-polarisation moves toward the right arm what is the outcome of the ECG

A

Positive blip,

a negative wave is moving towards the negativity of the arm = cancel each other out creating a positive potential

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14
Q

What is the PR interval and what is it mainly due to

A

Time from artirial depolarisation to ventricular depolarisation

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15
Q

What is PR interval mainly due to and how long is transmission

A

transmission through AV node

~0.1-0.2 sec

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16
Q

What is the QRS and how long does this take

A

Time for the whole of the ventricle to depolarise

(~ 0.08 sec)

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17
Q

What does the QRS prove

A

How well the Purkinje fibers are working

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18
Q

What does the QT interval show

A

time spent while ventricles are depolarised

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19
Q

What does the length of depolarisation depend on for the QT interval

A

Varies with Heart rate

20
Q

What is the length of the QT interval

A

0.42 sec at 60 bpm- resting HR

21
Q

Why cant you see arterial re-polorisation on an ECG

A

Because atrial repolarisation coincides with ventricular depolaristion. Ventricular depolarisation involves much more tissue depolarising much faster so it swamps any signal from atrial repolarisation.

22
Q

Why is the QRS complex so complex

A

Because different parts of the ventricle depolarise at different times in different directions

23
Q

What is the three directions of the QRS complex

A

1st – the interventricular septum depolarises to the right
2nd – the bulk of the ventricle depolarises from the endocardial to the epicardial surface going down the septum transverse
3rd – the upper part of the interventricular septum depolarises to the left

24
Q

Where is the summation of the QRS complex

A

add all togethers by wave of depolorisation going down the septum transverse

25
Q

Why is the T wave a positive blip if it is due to ventricular re-polarisation

A

The re-polarisation travels back the way towards the arm opposing direction of depolarisation, this is a negative charge moving in a negative direction therefore this negative double negative creates a net gain of a positive

signal moves away from recording electrode and produce this positive blip

26
Q

what is the interval from the beginning of the QRS to the apex of the T wave called

A

absolute refractory period

27
Q

what is the last half of the T wave refers to as

A

relative refractory period

28
Q

Why is the R wave bigger in SLL II compared to the others

A

as the main vector of depolorisation is is line with the recording of the left leg to the right arm going along the septum tranversum

29
Q

if hypertrophy occurred and the heart shifted towards the left where would the R wave be the biggest

A

Would get a bigger recording in SLL I

30
Q

if hypertrophy occurred and the heart shifted towards the right where would the R wave be the biggest

A

Would get a bigger recording in SLL III

31
Q

What is augmentended limb lead recording

A

recording from one limb lead with respect to the other two combined
- Electrical angles of the heart

32
Q

What is the benefit of augmented limb leads

A

it gives you 3 other perspectives on events in the heart

33
Q

What is the three other perspective gained from augmented limb lead recording

A

aVR, aVL and aVF

34
Q

Augmented limb lead recording produces what over all

A

give you 6 different views of events occurring in the frontal (or vertical) plane

35
Q

How is precordial chest leads aligned

A

These are arranged in front of the heart and therefore look at the same events, but in the transverse plane

36
Q

What are the results of the precordial chest leads

A

Look at the spread of depolarisation showing progression

flipping negative to positive waves

37
Q

What is the differentiation between limb leads and precordial chest leads

A

Limb meads look at: spread of depolarisation (and repolarisation) from 6 angles in the frontal plane
Precordial leads look at: the same events from 6 angles in the transverse plane

38
Q

What measuring technique one will affect the results of the ECG and why

A

precordial due to change in the spread of depolarisation

39
Q

What is the normal Heart rate, brachycardia, tachycardia

A

Normal - 60bpm
Brachy - < 60bpm
Tachy - > 60bpm

40
Q

What information does a rhythm strip tell me

A

Heart rate

41
Q

How do you measure heart rate on a rhythm strip

A

Measure the R - R interval
count how many occur in 60 seconds
or count how many occur in 30 large squares and multiply by 10

42
Q

What other information can be gathered by a rhythm strip

A

Is each QRS complex preceded by a P-wave
Is the PR interval too short (<0.12 sec) or too long (>0.2 sec)
Is the QRS complex too wide (>0.12 sec)
Is the QT interval too long (>0.42 sec at 60 bpm)

43
Q

What is elevated in a STEMI myocardial infarction

A

ST

44
Q

What does NSTEMI means

A

no ST elevated myocardial infarction

45
Q

What myocardial infarction is worse

A

STEMI

Cardiovascular system SA (43 decks)

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