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Cardio > The ECG > Flashcards

The ECG Flashcards

1
Q

what does an ECG do?

A

monitors electrical activity of the heart

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2
Q

How is the electrical activity of the heart recorded?

A

by electrodes on the body surface

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3
Q

How does the body surface get potential?

A

Currents that flow when the membrane potential of myocardial tissue is changing ie depolarising/repolarising

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4
Q

Only large/small masses of cardiac tissue generate sufficient current and what are these masses?

A

larger eg atrial and ventricular muscle

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5
Q

Why does the L ventricle give a larger signal on an ECG?

A

as larger mass on LH side of heart as thicker wall

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6
Q

What does a flat line indicate on an ECG?

A

the heart has stopped

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7
Q

What is the Pd measured between and in what unit?

A

mV and distant sites

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8
Q

What is the reading called on an ECG?

A

the electrocardiograph

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9
Q

What is the paper print out of the results?

A

the electrocardiogram

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10
Q

describe the physics of the ECG?

A

action potential causes a separation of charge,( difference in Pd), produces electric dipole which is a vector, generates an electric field, which varies over time, due to direction constantly changing

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11
Q

What is the ECG lead?

A

the imaginary line, the lead axis, between two (or more) electrodes, it is not the wire that connects the electrode to the recording device (the electrocardiograph)

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12
Q

what is the ‘seeing electrode’?

A

one electrode acts as the recording (positive) electrode

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13
Q

what generates the upward deflection on the ECG?

A

when depolarization moves towards the recording electrode

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14
Q

what generates the downward deflection on the ECG?

A

When depolarization moves away from the recording electrode

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15
Q

When is there no deflection on the ECG and why?

A

o If there is no movement towards or away from the recording electrode, there is no deflection on the ECG (it is isopotential) ie flat line
heart has stopped

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16
Q

What are the 3 groups of leads the 12 lead ECG is composed off?

A

3 standard limb leads (I,II,III)
3 augmented Voltage leads
6 Chest Leads

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17
Q

Name the 3 std limb leads and what they are called?

A

I,II,III

bipolar

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18
Q

Name the 3 augmented voltage leads and what they are termed?

A

(aVR (right), aVL (left) and aVF (foot)

unipolar

19
Q

Name the 6 chest leads and what they are termed?

A

V1-V6

Precordial Leads

20
Q

What are the leads that give the vertical(or frontal/coronal) view of the heart?

A

leads I,II, III, aVR, aVL and aVF

21
Q

What are the leads that give the horizontal/tranverse view of the heart?

A

V1-6

22
Q

What is the P wave?

A

Atrial depolarisation spreading from SA node inferiorly and to the left

23
Q

what is the movement of the depolarisation in the P wave?

A

moving towards the recording electrode (+ve) in lead II producing a (normally) upward deflection in this lead

24
Q

What does the P wave duration represent and what is the normal value for this?

A

P wave duration in the normal ECG reflects the time for the depolarization of atrial muscle to be complete. less than 0.120 s (120 ms)

25
Q

What does the QRS complex represent?

A

Ventricular activation/depolarisation

26
Q

what is the Q part of QRS complex?

A

downward (negative) deflection preceding an R wave

27
Q

what is the R part of QRS complex?

A

deflection upwards (positive) is called an R wave, irrespective of whether, or not, it is proceeded by a Q wave

28
Q

what is the S part of QRS complex?

A

downward (negative) deflection following an R wave

29
Q

What is the normal duration of a QRS complex?

A

100ms or less

30
Q

what causes the Q wave in the heart?

A

starts in the interventricular septum and spreads from left to right causing the small

31
Q

what causes the R wave in the heart?

A

 subsequently the main free walls of the ventricles depolarize causing a tall

32
Q

what causes the S wave in the heart?

A

, the ventricles at the base of the heart depolarize, producing a small

33
Q

What does the T wave represent?

A

Ventricular repolarisation

34
Q

What is the T wave?

A

It is an upward (positive) deflection because the wave of repolarization is spreading away from the recording electrode

35
Q

Where is V1 placed?

A

4th intercostal space RH side

36
Q

Where is V2 placed?

A

4th intercostal space LH side

37
Q

Where is V3 placed?

A

5th intercostal space mid clavicular line

38
Q

Where is V4 placed?

A

halfway between lead 2+4 on the rib between them

39
Q

Where is V5 placed?

A

5th intercostal space on the anterior axillary line

40
Q

Where is V6 placed?

A

5th intercostal space mid axillary line

41
Q

What is the PR interval?and std duration?

A

AV node delay

0.12-0.2s

42
Q

What is the QT interval?

A

depolarisation and repolarisation of ventricles

43
Q

how do you work out HR on a normal ECG?

A

HR = 300/no. of large squares between beats

44
Q

Name the 6 steps to analysing an ECG

A
  1. Verify patient details
  2. Check date and time ECG was taken
  3. Check calibration of ECG paper
  4. Determine axis
  5. Workout rhythm:
    - Is electrical activity present?
    - Regular or irregular?
    - Heart rate?
    - P waves present?
    - PR interval?
    - Each P wave followed by QRS?
    - QRS duration normal?
  6. Look at individual leads for voltage criteria changes OR any ST or T wave changes

Cardio (28 decks)

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