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My Cardiovascular > ECGs > Flashcards

ECGs Flashcards

1
Q

Describe the relative speed the action potentials, generated in the SA node conduct through:

i. Atria
ii. AV node
iii. Bundle of his
iv. Purkinje fibres

A

i. Rapid
ii. Relatively slowly.
iii. Very rapidly
iv. Rapidly.

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2
Q

Define what an ECG is.

A

A recording of potential changes,detected by electrodes positioned on the body surface, that allows the electrical activity of the heart to monitored.

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3
Q

What is responsible in the heart for generating a sufficient current which is detectable at the body surface?

A

Atrial and ventricular muscles

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4
Q

What does electrical activity within and between cardiac muscle cells cause what?

A
  1. current flow within the heart
  2. current flow within surrounding tissues.
  3. potential differences between distant sites on the body surface - this can be detected by electrodes placed on the skin connected to a ECG
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5
Q

What does the electrical dipole represent?

A

An electrical vector

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6
Q

What properties does an electrical vector have?

ii. why is this important?

A
  1. Magnitude
  2. Direction

ii. clinically it allows for the electrical axis of the heart to be estimated

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7
Q

What is the ECG lead?

A

It is the lead axis (imaginary line) between two or more electrodes.

It is NOT the wire that is connected to the ECG

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8
Q

What happens when depolarisation moves towards the recording electrode?

A

Upward deflection on the ECG.

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9
Q

What happens when depolarisation moves away from the recording electrode?

A

downward deflection on the ECG.

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10
Q

What is the 12 lead ECG made of?

A
  1. Three standard limb leads - bipolar (I,II and III)
  2. Three augmented voltage leads-unipolar - aVR (right) avF (foot) aVL (left)
  3. Six chest leads- precordial leads (V1-V6)
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11
Q

Where do you place the standard limb leads?

ii. What is the pattern refered to as

A
  1. Lead 1 - chest (Right arm to left arm)- left arm is recording electrode
  2. Lead 2- right arm (Right arm to left leg)- left leg is recording electrode
  3. lead 3- left arm (Left arm to left leg)- left leg is recording electrode
    ii. Einthoven’s triangle
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12
Q

Lead 2 sees the heart from which

direction?

A

Inferior.

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13
Q

What does the P wave represent in Lead II?

ii. How long is its normal duration

A

Shows atrial depolarisation.

as it moves inferiorly and to the left it moves towards the Lead II recording electrode (upward deflection)

ii. 0.12 seconds or less

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14
Q

What does QRS complex represent?

ii. How fast is it?

A

i. Ventricular activation.

ii. 0.1 s or less

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15
Q

Describe the movement of action potentials creating the QRS complex in Lead II.

A
  1. ventricular depolarization starts in the interventricular septum and spreads from left to right causing the small and narrow Q wave.

Moves AWAY from recording electrodes

  1. subsequently the main free walls of the ventricles depolarize causing a tall and narrow R wave

Move TOWARDS recording electrodes

  1. the ventricles at the base of the heart depolarize, producing a small and narrow S wave.

Moves AWAY from recording electrodes

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16
Q

What does the T wave represent in Lead II?

ii. Why is the T waves upward reflection different to the others on the ECG?

A

Ventricular repolarisation.

ii. ventricular repolarization refers to the negative charge moving away from recording electrode (i.e equivalent to positive charge moving towards it)

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17
Q

What is the Goldberger’s method?

A

refers to placement of augmented voltage leads
one +ve electrode (recording), two others linked as –ve. This effectively positions the reference (linked) electrode in the center of the heart to which the recording electrodes ‘look’

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18
Q

What is difference between augmented leads and standard limb leads

A

Augmented leads axes’ subtend the angles of einthoven’s triangle

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19
Q

The chest leads view the heart on different positions on which plane?

A

Horizontal plane.

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20
Q

What are the roles of the 6 chest leads?

A

V1 and 2 coming from the right, are ‘looking’ at the interventricular septum

V3 and 4 are ‘looking’ at the anterior of the heart

V5 and 6 are ‘looking’ at the lateral aspect (left ventricle) of the heart

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21
Q

What is the first positive defection in the QRS complex at V1

ii. What happens to this towards the V6 leads

A

R wave

ii. R wave Increases

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22
Q

What is the immediate negative deflection after the R wave in V1?

ii. what happens to this towards the V6 lead?

A

S wave

ii. S wave decreases

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23
Q

How can you an ECG trace to calculate:

  1. The heart rate.
A
  1. Either 300/ number of large square between two R waves
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24
Q

What is the ECG rhythm strip and what is its role?

A
  1. Prolonged record of one lead

2. Allows you to determine heart rate and identify the cardiac rhythm.

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25
Q

Why do we need 12 leads?

A
  1. Determine axis of the heart in thorax
  2. Look for any ST segment or T wave changes in relation to specific regions of the heart. This is crucial for diagnosing ischaemic heart disease.
  3. Looking for any voltage criteria changes.
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26
Q

What can ECGs detect?

A

To assess rhythm

Signs of
previous MI ( Q waves)
pre-excitation (Wolf Parkinson White syndrome)

27
Q

What would aortic stenosis look like on ECG?

A

Lateral T wave changes

LVH cause increase in QRS complex

28
Q

Profile for normal sinus rhythm

What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. Regular (60-100 bpm)
  2. Normal
  3. Normal (0.12-0.2 seconds)
  4. Normal (0.06-0.12 seconds)
29
Q

Profile for Atrial fibrillation

What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. Atrial - very fast ( greater than 300 bpm)
    in comparison ventricular rate can be slow, normal or fast
  2. Absent- replaced erratic waves
  3. absent
  4. normal
30
Q

Profile for Asystole
What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. None
  2. Absent
  3. Absent
  4. Absent
31
Q

Profile for Atrial flutter
What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. Atrial= fast

Ventricular = slow

  1. Not observable ( saw-toothed waves)
  2. Not measurable
  3. Normal
32
Q

Profile for Bundle branch block

What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. Regular
  2. Normal
  3. Normal
  4. Wide
33
Q

Profile for First degree heart block

What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. Regular
  2. Normal
  3. Prolonged
  4. Normal
34
Q

Profile for Second degree heart block (morbitz type 1)

What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. Regular
  2. Normal
  3. Progressively longer until QRS complex is missed.
  4. Normal
35
Q

Profile for second degree heart block (morbitz type II)

What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. Atrial is faster than ventricle
  2. Normal but more P waves than QRS complex
  3. Normal or prolonged
  4. Normal or wide
36
Q

Profile for Third degree heart block

What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. Atrial rate normal and faster than ventricular rate
  2. Normal may appear within QRS complex
  3. Absent. Atria and ventricles beat independently
  4. Normal
37
Q

Profile for ventricular fibrillation

What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. immeasurable
  2. Absent
  3. immeasurable
  4. None
38
Q

Profile for Ventricular tachycardia

What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
A
  1. Fast
  2. Absent
  3. Immeasurable
  4. wide

Looks like continuos mountains

39
Q

Profile for Wolf parkinson white syndrome

What is the character of the:

  1. Rate
  2. P wave
  3. PR interval
  4. QRS complex
    ii. What extra wave is present?
A
  1. Normal
  2. Normal
  3. Can be short
  4. Usually wide
    ii. delta wave
40
Q

Which one is the recording electrode?

A

the positive electrode

41
Q

What is the magnitude of the electrical dipole determined by?

A

The mass of the cardiac muscle that is involved in the generation of the current ( atria and ventricles dominate)

42
Q

What is the direction of the electrical dipole determined by?

A

Determined by the overall activity of the heart at any instant in time- varies during cardiac cycle

43
Q

What does Isopotential mean?

A

No deflection has occurred on the ECG as depolarisation has not moved towards or away from the electrode

44
Q

which leads are responsible for showing the coronal (vertical) plane of the heart?

A

Standard limb leads

Augmented voltage leads

45
Q

Which leads are responsible for showing the transverse (horizontal) plane of the heart?

A

Chest leads

46
Q

What does the PR interval show?

ii. why is it diagnostically important?

A

Time for SA node to impulse to reach ventricles

ii. heavily influenced by delay in AV node

47
Q

What is the ST segment described as?

ii. why is it diagnostically important?

A

Isoelectric- normally no elevation or depression from isoelectric plane

ii. if there is a depression or elevation then there might be an issue

48
Q

What is the QT segment represent?

A

Time for ventricular depolarisation and repolarisation

49
Q

What is the normal time of PR interval?

A

0.12-0.2s

50
Q

What is the normal time of QT interval?

A
  1. 44s male

0. 46s female

51
Q

Discuss the placement of augmented voltage leads.

A

aVR - RA (+) – LA & LF (-)

aVL - LA (+) – RA & LF (-)

aVF - LF (+) – RA & LA (-)

52
Q

What is the difference between aVR and Lead II waves on ECG?

A

Predominant vector is moving away from positive electrode in ECG for aVR (waves are negative)

Predominant vector is moving towards positive electrode in ECG for Lead II (waves are positive)

53
Q

Where do Lead I and aVL view the heart?

A

Left side ( Left arm) - lateral leads

54
Q

Where do Lead II, III and aVF view the heart?

A

inferiorly ( left foot) - inferior leads

55
Q

Where do you place the 6 chest leads?

A
  1. V1 - Fourth intercostal space immediately right of sternum
  2. V2- fourth intercostal space immediately left of sternum
  3. V3 - Mid way between V2 and V 4
  4. V4 - fifth intercostal space mid clavicular line
  5. V5 - same horizontal level as V4 anterior axillary line
  6. V6 - same horizontal level as V4 mid axillary line
56
Q

What’s the difference between ST and TP segment on Lead II?

A
  1. ST shows ventricular systole

2. TP shows ventricular diastole

57
Q

Which leads pick up ST elevation in the circumflex artery?

A

I, aVL,v4-v6

58
Q

Which leads pick up the ST elevation in LAD?

A

V1-v3

59
Q

Which leads pick up ST elevation in the right coronary artery ?

ii. what other leads might have reciprocal changes due to this?

A

II,III,aVF

ii. I and aVL

60
Q

which leads pick up the ST elevation in the circumflex artery?

A

V7-V9

20% can also have II,III,aVF

61
Q

After a posterior MI what will not show up on an ECG?

A

Q waves

ST elevation

Hyperacute T waves

62
Q

What are the normal limits of the cardiac axis on an ECG?

A

-30 to 90 degrees

below - 30 = left axis deviation

above 90 = right axis deviation

63
Q

What are the ECG changes caused by hyperkalaemia

ii. what might be seen in hypOkalaemia?

A

Absent P waves

Broad QRS complexes

Tall tented T waves

ii. u waves

64
Q

what might a subendocardial infarction show on an ECG?

A

ST elevation in most leads

mainly associated with shock

My Cardiovascular (8 decks)

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