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JL Cardiovascular > ECG > Flashcards

ECG Flashcards

1
Q

What is the electrocardiograph?

A

Potential differences between distant sites on the body surface measurable by electrodes placed on the skin coupled to a sensitive recording device, the electrocardiograph.

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2
Q

What is the term for a recording of potential differences between sites on the body surfaces?

A

Electrocardiogram (ECG or /EKG)

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3
Q

What is a charge seperation called?

A

A dipole

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4
Q

What does the dipole gnerate that are measurable with two electrodes?

A

Electrical field (line of isopotential)

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5
Q

What is a lead axis?

A

The imaginary line connecting the two electrodes measuring the electrical field

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6
Q

When is the measured potential difference the greatest?

A

When the lead axis is parallel to the direction of the dipole (electrical vector)

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7
Q

What is the measured potential difference when the lead axis is perpendicular to the direction of dipole (electrical vector)?

A

0

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8
Q

What represents an electrical vector?

A

The dipole

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9
Q

What does the electrical vector have components of?

A

Magnitude (length of arrow) and direction (orientation of arrow)

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10
Q

What is magnitude of electrical vectors determined by?

A

The mass of cardiac muscle that is involved in the generation of the signal.

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11
Q

What is direction of electrical vectors determined by?

A

The overall activity of the heart any instant in time and varies during the cardiac cycle.

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12
Q

What limb leads are bipolar?

A

The standard limb leads

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13
Q

In lead I (RA to LA) - which is negative and which is positive?

A

RA is negative

LA is positive

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14
Q

In lead II (RA to LL) - which is positive and which is negative?

A

RA is negative

LL is positive

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15
Q

In lead III (LA to LL) - which is positive and which is negative?

A

LA is negative

LL is positive

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16
Q

What king of deflection does depolarisation moving towards the recording electrode give?

A

An upward deflection

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17
Q

Which leg is earthed for an ECG?

A

Right leg

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18
Q

How long does the P wave last?

A

0.08 - 0.10 seconds

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19
Q

In which part of the ECG is there action potential upstroke throughout atrial muscle?

A

P wave

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20
Q

How long is the QRS complex?

A
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21
Q

In which part of the ECG is there action potential upstroke throughout ventricular muscle?

A

QRS complex

22
Q

How long is the PR interval and what does it represent?

A

0.12 - 0.20 s

Represents largely AV node delay

23
Q

Which part of the ECG is maintained ventricular depolarisation? (sytole)

A

ST segment

24
Q

Which part of the ECG represents diastole?

A

TP intervale

25
Q

When is the ECG isoelectric?

A

During the PR interval, ST segments and TP interval

26
Q

Which leads are unipolar?

A

Augmented limb leads

27
Q

What is Goldberger’s method?

A

One positive electrode, two others linked as negative

28
Q

What is the augmented voltage right (aVR)?

A

RA (+) to [LA & LF] (-)

29
Q

What is the augmented voltage left (aVL)?

A

LA (+) to [RA & LF] (-)

30
Q

What is augmented voltage food (aVF)?

A

LF (+) to [RA & LA] (-)

31
Q

What leads view the heart from a different angle compared to the standard limb leads (their axes subtend the angles of Einthoven’s triangle)?

A

Augmented leads

32
Q

Where does electrical activity within the cardiac muscle cells cause current to flow?

A

Within the heart and the surrounding tissues

33
Q

aVR ianverted - describe the vector?

A

Predominant vector is depolarisation moving away from the electrode

34
Q

Poorly resolved P and T waves - describe vector?

A

Predominant vector is approximately perpendicular to the lead axis

35
Q

Descrive the vector in well resolved P and T waves?

A

Predominant vector is approximately parallel to the lead axis

36
Q

What polarity are chest (precordial) leads?

A

Unipolar

37
Q

What plane are the chest leads in and what plane are the limb leads in?

A

Chest leads - horizontal plane

Limb leads - frontal plane

38
Q

What should the calibration of ECG trace be?

A

Paper speed 25mm/sec

39
Q

In an ECG what is the y axis?

A

Amplitude

40
Q

In an ECG what is the x-axis?

A

Time

41
Q

What should the amplitude be measured in?

A

10mm/1mV

42
Q

What does one large box represent, in time and in amplitude?

A

0.2 seconds

5mm amplitude

43
Q

What does one small block represent, in time and in amplitude?

A

0.04 seconds

1mm of amplitude

44
Q

Give two methods of working out heart rate on an ECG?

A
  1. 300/number of large squares between beats

2. 300/numvber of large squares between R-R interval

45
Q

Which lead is usually the rhythm strip?

A

Lead II

46
Q

What is the rhythm strip and what does it allow you to detect?

A

Prolonged recording of one lead and allows you to detect rhythm disturbance

47
Q

What are the 7 steps in the practical approach to analysing the ECG?

A

(first determine the rhythm from the rhythm strip)

  1. Is electrical activity present
  2. Is the rhythm regular or irregular
  3. What is the heart rate?
  4. P-waves present?
  5. What is the PR interval?
  6. Is each P-wave followed by a QRS complex?
  7. Is the QRS duration normal?
48
Q

What three conditions does a normal resting ECG not exclude?

A
  1. MI
  2. Intermittent rhythm disturbance
  3. Stable angina
49
Q

If intermittent rhythm disturbance is suspected, what do you do?

A

Do ambulatory ECG recording for 24 hours or 7 days

50
Q

If stable angina is suspected, what do you do and look for?

A

Do exercise ECG

Look for ST changes during/after exercise

51
Q

If the heart rate is irregular how do you work out the heart rate?

A

Count number of QRS complexes in 30 large squares and multiply by 10

JL Cardiovascular (18 decks)

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