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CR 2 > ECG Review > Flashcards

ECG Review Flashcards

1
Q

When interpreting an ECG, which order would you address the various aspects in

A
  • Rate
  • Rhythm
  • Atrial activity
  • One p wave before each QRS?
  • P wave normal duration
  • PR interval normal duration
  • QRS normal duration
  • ST segment normal (elevated/ depressed?
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2
Q

How do you manually calculate heart rate from an ECG

A

Number of R waves in 15 large grid squares * 20

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3
Q

How can you see if RR intervals are the same

A

Marks where the R ares on piece of paper and move along to see if they’re the same

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4
Q

What does the P wave represent

A

Atrial depolarisation

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5
Q

How long should P waves be

A

No longer than 2 small squares (0.08s/ 80ms)

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6
Q

What time period is represented by one square on an ECG

A

0.04

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7
Q

What is represented by the PR interval

A
  • Time to cross the AV node and propogate via bundle of His to the ventricles
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8
Q

How long should the PR interval be

A

120-200ms

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9
Q

What does a PR interval of >200ms indicate?

A

A form of heart block
Hypokalaemia
Acute rheumatic fever
Carditis

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10
Q

What does QRS complex indicate

A

Synchronisation of the contraction of ventricular muscles

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11
Q

How long should QRS complex be

A

<120ms in duration

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12
Q

Describe how a normal ECG would appear (5)

A 
60-100bpm
Regular rhythm
P wave <80ms
PR interval <200ms
QRS duration <120ms
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13
Q

Define sinus bradycardia

A

A heart rate <60bpm

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14
Q

What may cause sinus bradycardia (4)

A

1- Healthy, athletic person
2- Drug abuse
3- Hypoglycaemia
4- Brain injury

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15
Q

What medication commonly causes sinus bradycardia

A

Beta blockers

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16
Q

Define sinus tachycardia

A

A heart rate >100bpm

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17
Q

Where does sinus tachycardia originate from

A

SA node

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18
Q

Describe how ventricular tachycardia appears

A

Rate= 180-190bpm
Prolonged QRS
P wave not seen
‘Just looks wrong- dips downwards kind of into V shapes’

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19
Q

What can cause ventricular tachycardia

A

MI, Coronary artery disease, poor heart structure

Abnormal tissues in ventricular generate rapid and irregular heart rate

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20
Q

How may ventricular tachycardia lead to cardiac arrest

A

Poor cardiac output leads to cardiac arrest

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21
Q

Describe how ventricular fibrillation appears on an ECG

A

Irregular rhythm, rate >300bpm

Disorganised, no recognisable QRS, P wave not seen

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22
Q

What happens to patient in ventricular fibrillation

A

Disorganised electrical signals cause the ventricles to quiver instead of contract
Patient will be unconcious as blood not pumped to brain- DEFIB

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23
Q

How can you distinguish ventricular tachycardia and ventricular fibrillation on an ECG

A

In VT rhythm and amplitude of QRS are normal, just a lot faster

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24
Q

What do all forms of heart block have in common

A

PR interval >200ms

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25
Q

What is first degree heart block, and is it a problem

A
  • PR interval is fixed, constant duration >200ms
  • Regular rate
  • Rarely causes problems, common amongst athletes
26
Q

What is second degree heart block type 1

A
  • Each successive impulse from atria finds more difficult to pass AVN
  • PR interval gets progressively longer until P wave is not followed by QRS
  • After this, system resets
27
Q

What is second degree heart block aka

A

Wenkenbach

28
Q

What happens in second degree heart block type 2?

A

AVN randomly fails to respond to some atrial impulses

Rate is irregularly irregular

29
Q

What is third degree heart block

A

Impulses from atria do not connect with ventricles

Ventricular rhythm independent from atrial

30
Q

What rate is usually present in third degree heart block and why

A

Bradycardia

  • Ventricles generate their own signal from a focus somewhere in the ventricle
  • Ventricular escape beats are slow
31
Q

What symptoms are often present in atrial fibrillation

A
  • Palpitations
  • Fainting
  • Chest pain
  • Congestive heart failure
  • May be asymptomatic
32
Q

What is the underlying mechanism of atrial fibrillation

A
  • Many sites within the atria, not just the SAN, generate electrical impulses
  • This leads to irregular conductions to ventricles
33
Q

How will an ECG of somebody with atrial fibrillation appear?

A
  • Rate: 100-160bpm
  • Rhythm: irregularly irregular
  • QRS: normal
  • P wave: absent
34
Q

What is the underlying mechanism of atrial flutter

A
  • Re-excitation of electrical impulses causes high frequency bombardment of AVN
  • High but regular rhythm
35
Q

Describe how an ECG of somebody with atrial flutter would appear

A

110bpm
Regular rhythm
P waves replaced with flutter waves
P wave rate= 300bpm

36
Q

What is junctional rhythm

A

Damage to SAN/ blockage on conduction pathway causes the AVN to take over as the pacemaker

37
Q

Describe how an ECG appears if junctional rhythm is occuring

A
  • 40-60bpm
  • Regular rhythm
  • Normal QRS complex
  • P wave ratio 1:1. Inverted in lead 2
  • P-R interval is the same
38
Q

What is happening in supraventricular tachycardia

A
  • Abnormality in or near the AVN

- High frequency of impulses at the AVN

39
Q

Describe how an ECG appears for supraventricular tachycardia

A

140-220bpm
Regular rhythm
QRS duration is normal
P wave is absent or buried in preceding T wave
P-R interval differs depending on the site of the pacemaker

40
Q

What is the most common form of supraventricular tachycardia

A

AV nodal reentrant tachycardia

41
Q

What % of cases of AVNRT occur in women and what is the main symptoms

A

75%

Palpatations

42
Q

Describe the underlying mechanism of AVNRT

A
  • Occurs when reentry circuit forms within on just next to AVN
  • Atrial impulses go around in a circle instead of dying away causing repeated activation of AVN after a short time
43
Q

What 2 anatomical pathways are involved in AVNRT and where are they located

A

Fast and slow pathways

Both located in the right atrium

44
Q

What is the main difference seen on an ECG of somebody with bundle branch block

A

Widening of the QRS complex

Notch on the R wave

45
Q

What does RBBB indicate

A

Problems with the right side of the heart

46
Q

What does LBBB indicate

A

Heart disease

47
Q

How can you distinguish between left and right bundle branch block?

A

WiLLiaM MaRRoW
LBBB–> There is a ‘w’ shape in v1 and an ‘m’ in v6
RBBB–> There is an ‘m’ in v1 and a ‘w’ in v6

48
Q

What does the ST segment represent

A

Time where both the ventricles are fully depolarised

49
Q

How long should the ST segment be?

A

80-120ms

50
Q

How should the ST segment appear and why

A

It should be flat or isoelectric because if both ventricles are working correctly their voltage will cancel out

51
Q

What is indicated by a downsloping ST segment

A

Coronary ischaemia

Hypokalemia

52
Q

What does STEMI stand for

A

ST elevation myocardiac infarct

53
Q

What must the ECG show for a person to qualify as a STEMI

A

new ST elevation in 2 or more adjacent ECG leads

54
Q

What leads should you be looking at to determine electical axis

A

Leads 1 and aVF

55
Q

What does it mean if the QRS complexes are overall positive in both leads 1 and aVF

A

Normal electrical axis

56
Q

What is the normal quadrant for the electrical axis of the heart to be in

A

0-90 degrees

57
Q

What would you see if the electric axis for the heart is left axis deviated

A

Lead 1 positive

aVF negative

58
Q

What would you see if the electrical axis for the heart is right axis deviated

A

Both negative

59
Q

What quadrant/ degrees would the electrical axis of the heart be in if lead 1 was positive but avf was negative?
What could this indicate

A

Left upper quadrant
0–90 degrees
Possible LAD

60
Q

What quadrant/ degrees would the electrical axis of the heart be in if lead 1 was negative but avf was positive?
What could this indicate

A

Right lower quadrant
90-180 degrees
Possible RAD

61
Q

What quadrant/ degrees would the electrical axis of the heart be in if both Lead 1 and avf were negative?
What could this indicate

A

Right upper quadrant
-90-180 degrees
Extreme axis deviation

CR 2 (33 decks)

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