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Cardiorespiratory 2 > ECG Review > Flashcards

ECG Review Flashcards

1
Q

what is the beginning of the ST segments called

A

J point sometimes

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2
Q

Name the steps in the ECG protocol

A
  1. What is heart rate? (look at RR intervals)
  2. What is heart rhythm? : (Is rate regular or irregular? )
  3. Can you see a P wave? Is there one P wave before each QRS complex? Is the P wave of normal duration?
  4. Is the PR interval of normal duration ?
  5. Is the QRS complex of normal duration?
  6. Is the ST interval elevated or depressed? Is the QT interval normal? Is the T wave inverted?
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3
Q

how do you work out the heart rate

A
  • Count the number of R waves in 30 oarge grid sqautes and multiply by 10
  • 1 sqaure = 0.04ms
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4
Q

how do you work out the rhythm

A
  • Determined by the interval between the RR waves

- Check if all the RR intervals are the same

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5
Q

what does it indicate if there is variable RR intervals

A
  • Variable RR intervals indicate some kind of heart block
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6
Q

what lead is P wave always positive in sinus rhythm

A
  • P wave is always positive in lead II during sinus rhythm
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7
Q

describe how long the p wave should be

A
  • P wave should be not more than about 2 small squares long (0.08s or 80ms)
  • 80-120ms
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8
Q

what changes to an ECG are shown if the atria becomes enlarged

A
  • If an Atria becomes enlarged its contribution to the P wave will be enhanced,
  • enlargement of the left and right atria causes typical P wave changes in lead II and lead VI
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9
Q

what does the PR interval tell us

A
  • Tells us about the time it takes for the conduction from the atria through the AV node to the ventricles
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10
Q

how long should the PR interval be

A

120-200 ms (three to five small squares).

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11
Q

if a PR interval is over 200ms what does it mean

A
  • A PR interval of over 200 ms usually indicates a form of heart block, usually due to slow conduction through the AV node.
  • Prolongation can also be associated with hypokalemia, acute rheumatic fever, or carditis.
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12
Q

What is the QRS complex

A
  • The QRS complex is measured from the start of Q wave to finish of S wave ( Q wave often absent in normal ECG)
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13
Q

what does the QRS complex show

A
  • Contraction starts in the apex – this is the upstroke of the R wave
  • Down stroke of the R wave is when the contraction reaches the start of the ventrciles
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14
Q

what is QRS complex an indication of

A
  • The QRS complex or interval is an indicator of the synchronisation of the contraction of the ventricular muscle
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15
Q

what does a long QRS complex indicate

A
  • A long QRS duration indicates that ventricular depolarization is slow, or that part of the ventricular muscle is not contracting normally
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16
Q

how long is the QRS complex supposed to be

A
  • it should be less than 120ms in duration (3 small sqaures)
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17
Q

what does a flat ST segment indicate

A
  • it indicates that all the ventricles are contracting together
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18
Q

what is the ST measured to

A

measured from the start of the Q wave to finish of the Wave

- measured to the end of the T wave

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19
Q

what does the QT/ST interval depend on

A

QT interval depends on heart rate

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20
Q

what is the heart rate adjusted QT interval called

A
  • the corrected QT interval - (QTc interval)
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21
Q

what is a long QTc interval indiciative of

A
  • a long QTc interval indicates an increased risk of ventricular arrhythmias
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22
Q

what depolarises first the endocardial or epicardial layer

A
  • The inner (endocardial) layer of ventricular muscle which includes the papillary muscle depolarises first . (This pulls the AV valves closed).
  • The outer (epicardial) layer of muscle depolarises slightly later
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23
Q

when the endocardial muscle contracts what does it pull close

A
  • it pulls the AV valves closed
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24
Q

what is the T wave due to

A

T wave is due to the timing of the repolarisation of different parts of the ventricles

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25
Q

what can cause an inverted T wave

A
  • The inner (endocardial) layer of ventricular muscle is more susceptible to the effects of ischaemia; this reduces the duration of the endocardial action potential
  • If the outer (epicardial ) muscle layer has a normal duration we can get an inverted T wave as the endocardial AP is now shorter than the epicardial
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26
Q

what are inverted T waves associated with

A
  • Inverted T waves can be benign in children but in adults they are often associated with..
  • coronary artery disease
  • pulmonary damage such as pulmonary embolism
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27
Q

what is the definition of sinus bradycardia

A
  • A heart rate less than 60 beats per minute
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28
Q

describe sinus bradycardia

  • rhythm
  • QRS duration
  • P wave
  • PR interval
A 
Rhythm - Regular
QRS Duration - Normal 
P Wave - Visible before each QRS complex 
P Wave – normal duration
P-R Interval - Normal duration
29
Q

what is sinus bradycardia seen

A
  • it is usually benign and often seen in patients on beta blockers
  • may be due to increased vagal tone from drug abuse
  • hypoglycaemia
  • brain injury
  • athletes
30
Q

define sinus tachycardia

A

high More than 100 beats per minute

31
Q

describe sinus tachycardia

  • rhythm
  • QRS duration
  • P wave
  • PR interval
A
  • Rhythm - Regular
  • QRS Duration - Normal
  • P Wave - Visible before each QRS complex
  • P Wave – normal duration
  • P-R Interval - Normal
32
Q

what does sinus tachycardia originate form

A
  • it originates from the SA node
33
Q

what are the causes of sinus tachycardia

A
  • stress, fright, illness, exercise
  • not abnormal if it is triggered to response of illness or injury
  • but I their is no apparent trigger than medication may be required to suppress the rhythm
34
Q

describe ventricular tachycardia

  • rate
  • rhythm
  • QRS duration
  • P wave
A
  • Rate - 180-190 Beats per minute
  • Rhythm - Regular
  • QRS Duration - Prolonged
  • P Wave - Not visible
35
Q

What does ventricular tachycardia result from

A
  • Results from abnormal tissues in the ventricles generating a rapid and irregular heart rhythm and patient is at risk of cardiac output
36
Q

what is the difference between ventricular tachycardia and ventricular fibrillation

A
  • Ventricular tachycardia is not the same as ventricular fibrillation in VT the rhythm and amplitude of the QRS complex is regular it is just faster than normal
37
Q

describe ventricular fibrillation

  • rate
  • rhythm
  • QRS duration
  • P wave
A
  • Rhythm - Irregular
  • Rate - 300+, disorganised
  • QRS Duration - Not recognisable
  • P Wave - Not seen
38
Q

what causes ventricular fibrillation

A

Disorganised electrical signals cause the ventricles to quiver instead of contract in a rhythmic fashion

39
Q

when does ventricular fibrillation occur

A
  • This condition may occur during or after a myocardial infarct.
  • Due to the asynchronous contraction there is little or no cardiac output.
    • IMMEDIATE TREATEMTN BY DEFIBRILLATION IS VITAL
40
Q

describe the features of first degree heart block

A
  • PR interval is a fixed constant duration greater than 200ms
  • The rate is regular
  • Condition rarely causes any problems by itself and often trained atheletes can be seen to have it
41
Q

describe the features of second degree heartblock type 1 wekebach

A
  • PR interval gets progressively longer until the P wave is not followed by a QRS
  • After this the system resets and repeats
42
Q

describe the features of second degree heart block type 2

A
  • P wave is regular but AV node randomly fails to respond to some atrial impulses
  • Ventricular rate is irregularly irregular
  • Do an angiogram see if there is a blockage
43
Q

describe the features of third degree heart block

A
  • P waves present but unsynchronised with QRS complex. The ventricles generate their own signal from a focus somewhere within the ventricle.
  • These ventricular ‘escape’ beats are usually slow, so marked bradycardia present
  • There is no relationship between PR and QRS complex
44
Q

what causes Atrial fibrillation

A
  • In AF many separate sites within the atria, not just the SAN, are generating electrical impulses, leading to irregular conduction of impulses to the ventricles
45
Q

what symptoms is Atrial fibrillation associated with

A

It may cause no symptoms, but it is often associated with…

  • palpitations
  • fainting
  • chest pain
  • congestive heart failure
46
Q

who is Atrial fibrillation common in

A

the elderly

47
Q

describe Atrial fibrillation

  • rate
  • rhythm
  • QRS duration
  • P wave
  • PR interval
A
  • Rate - usually 100-160 beats per minute but slower if on medication
  • Rhythm - Irregularly irregular
  • QRS Duration - Usually normal
  • P Wave - Not distinguishable
  • P-R Interval - Not measurable
48
Q

why can you get tachycardia with atrial fibrillation

A
  • Can also get tachycardia associated with this, this reduces the stroke volume
  • It is a consequence of the poor cardiac output caused by the atrial fibrillation
49
Q

describe what causes atrial flutter

A
  • Re-excitation of electrical impulses in the atria cause a high frequency bombardment of AV node (~300 bpm) leading to a high but regular heart rhythm
50
Q

describe atrial flutter

  • rate
  • rhythm
  • QRS duration
  • P wave
  • PR interval
A
  • Rate - Around 110 beats per minute
  • Rhythm - Regular
  • QRS Duration - Usually normal
  • P Wave - Replaced with multiple F (flutter) waves,
  • P Wave rate - 300 beats per minute
  • P-R Interval - Not measurable
51
Q

describe the difference between atrial flutter and atrial fibrillation

A

Atrial fibribllation
- A ‘firework display’ of separate atrial pacemakers going off like a bunch of rockets
Atrial flutter
- One atrial pacemaker generating a re-entrant or circus excitation going round and round at a fast rate

52
Q

what causes junctional rhythm

A
  • In junctional rhythm there is damage to the sinoatrial node or a block in the conduction pathway in the atria
  • When this happens, the atrioventricular node takes over as the pacemaker
53
Q

what are the features of junctional rhythm

A
  • bradycardia
  • normal QRS complex
  • P wave will normally be absent or inverted
54
Q

describe junctional rhythm

  • rate
  • rhythm
  • QRS duration
  • P wave
  • PR interval
A
  • Rate - 40-60 Beats per minute
  • Rhythm - Regular
  • QRS Duration - Normal
  • P Wave - Ratio 1:1 if visible. Inverted in lead II
  • P Wave rate - Same as QRS rate
  • P-R Interval - Variable
55
Q

describe supraventricular tachycardia

  • rate
  • rhythm
  • QRS duration
  • P wave
  • PR interval
A
  • Rate - 140-220 beats per minute
  • Rhythm - Regular
  • QRS Duration - Usually normal
  • P Wave - Absent or buried in preceding T wave
  • P-R Interval –Depends on site of supraventricular pacemaker
56
Q

what causes supra ventricular tachycardia

A

There is a high frequency of impulses generated at or near the AV node (which override those from the SA node) .
- The effect is very similar to atrial flutter:SVT can occur in all age groups

57
Q

name the most common type of regular supra ventricular tachycardia

A
  • AV nodal reentrant tachycardia (AVNRT)
58
Q

when does - AV nodal reentrant tachycardia (AVNRT) occur

A
  • AVNRT occurs when a re-entry circuit forms within or just next to the atrioventricular node
  • This means that the atrial impulses instead of dying away after activating the AV node go around ‘in a circle’ and then activate the AV node again after a short delay.
59
Q

what is the main symptoms of AVNRT

A

palpitations

- It is more common in women than men (approximately 75% of cases occur in females due to oestrogen hormone

60
Q

describe bundle branch block

  • rate
  • rhythm
  • QRS duration
  • P wave
  • PR interval
A
  • Rate - Normal
  • Rhythm – Regular
  • QRS Duration - Prolonged
  • P Wave -normal
  • P Wave rate - Normal and same as QRS rate
  • P-R Interval – Normal
61
Q

what causes bundle branch block

A
  • Abnormal conduction through the bundle branches will cause a depolarization delay through the ventricular muscle, the ventricles wont contract at the same time, this delay shows as a widening of the QRS complex
  • . Right Bundle Branch Block (RBBB) indicates problems in the right side of the heart.
  • Whereas Left Bundle Branch Block (LBBB) is an indication of heart disease.
62
Q

what does the ST segment represents

A

ST segment represents the time when all ventricular tissue is fully depolarised

63
Q

what should the duration of the ST segments be

A

80-120ms (same as QRS complex)

64
Q

what can a depression of ST segments mean

A
  • Depression ST segements can indicate coronary ischaemia or hypokalaemia
65
Q

what is a STEMI

A
  • STEMI – ST Elevation associated with an MI

- STEMI is a form of MI where the ST interval is elevated above normal

66
Q

what does a person need to qualify as having a STEMI

A

For a person to qualify as having a STEMI, the ECG must show new ST elevation in two or more adjacent ECG leads.

67
Q

describe a STEMI

  • rate
  • rhythm
  • QRS duration
  • P wave
  • PR interval
A
  • Rate - 80 Beats per minute
  • Rhythm - Regular
  • QRS Duration - Normal
  • P Wave - Normal
68
Q

What is an NSTEMI

A

Some people have an MI without ST elevation. This is called NSTEMI.
- It is usually a less serious form where there is cardiac ischaemia but not necessarily regions of cardiac muscle death

Cardiorespiratory 2 (43 decks)

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