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Year 3 - CR > Interpretation of ECG > Flashcards

Interpretation of ECG Flashcards

1
Q

Name the parts that make up the ECG

A
  • P wave
  • QRS
  • T wave
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2
Q

What does the P wave signal

A

atrial depolarisation

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3
Q

What does the QRS complex signal

A
  • ventricle depolarisation
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4
Q

What does the T wave signal

A
  • Ventricular repolarisation
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5
Q

What should the first thing in an ECG should you look at

A
  • to make sure you are looking at the right person ECG - check the name, date of birth and hospital number
  • its calibration - 1mV = 10mm
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6
Q

What are the two calibration numbers that you should remember

A
  • Paper speed should be 25mm/sec
  • calibration should be 1mV = 10mm
  • these are at the bottom of most ECG
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7
Q

What should the paper speed in an ECG be

A

25mm/sec

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8
Q

Where should the chest leads go

A

6 of them

  • V1 - 4th intercostal space on the right sternum
  • V2 - 4th intercostal space on the left sternum
  • V4 - 5th intercostal space midclavicular line (apex beat)
  • V3 between V4 and V2
  • V6 - mid axillary line
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9
Q

what does the chest lead allow you to do

A
  • Look at the QRS complex from different planes
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10
Q

describe how the QRS becomes positive

A
  • It becomes positive by the time you reach V4
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11
Q

name the 6 limb leads

A 
I 
II
III
aVR
aVF
aVL
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12
Q

Out of the limb leads which should be positive and negative

A 
I - QRS is meant to be positive 
II - QRS is meant to be positive 
III- QRS is meant to be positive 
aVR - should always be negative 
aVF - QRS is meant to be positive 
aVL - halfway between the right direction so half and half
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13
Q

when is QRS positive

A

QRS is positive when ventricular depolarisation is in the right direction

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14
Q

Name the chest leads

A

V1-V6

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15
Q

Name the normal ECG wave forms and what is normal

A
  • PR = 120-200 msec (3-5 small Sq)
  • QRS < 120 msec (< 3 small Sq)
  • QTc < 440 msec
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16
Q

what does 1 small sequence and 1 big sequence in msec

A

1 small Sq = 40 msec

1 big square= 200 msec

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17
Q

How do you work out the QTc

A

QT/ square root of RR

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18
Q

what is the QTc dependant on

A
  • it is dependant on the heart rate
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19
Q

How do you read an ECG

A 
– Rhythm
– Rate
– Axis
– P waves
– PR interval/ heart block
– QRS morphology/ ST segments/ T waves 
– QT interval
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20
Q

How do you assess Rhythm

A
  • are the QRS regular complexes

- is there a P wave before every QRS

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21
Q

What is the definition of sinus rhythm

A
  • there is a P wave before every QRS

- requires an ECG to know

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22
Q

What is sinus arrhythmia

A
  • variation of RR interval with respiration

- normal variant

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23
Q

Why is lead II used to look at the P wave and thus used in rhythm

A

one of the best leads to look at the p wave

- atrial depolarisation is in the same direction

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24
Q

What are ectopics

A

When you heart throws up some extra beats

  • ectopics above the AV node are called supraventricular ectopics
  • ectopics below the AV node are called ventricular ectopics
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25
Q

What is the difference between supra-ventricular and ventricular ectopics

A

Supraventricular

  • ectopics above the AV node are called supraventricular ectopics
  • narrow QRS complex

Ventricular

  • ectopics below the AV node are called ventricular ectopics
  • Broad QRS complex
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26
Q

What is the normal heart rate

A

50-100bpm

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27
Q

How do you calculate heart rate

A
  • look at the RR interval
  • count the number of squares between the QRS complex
  • number of big squares and then divide 300 by the number of big squares
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28
Q

who can you not calculate heart rate in

A
  • Patients who have an irregular heart rhythm
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29
Q

What is the axis

A

Axis is the net electrical vector of the heart

- gives an overall idea of the direction of depolarisation

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30
Q

in what direction does the heart depolarise

A
  • from the top of the right shoulder and down

- from aVR to II

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31
Q

What is the normal electrical axis

A

-30 to +120

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32
Q

what is the axis in left axis deviation and right axis deviation

A

Left axis deviation is when the axis is greater than -30

right axis deviation is when the axis is greater than +120

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33
Q

if lead II is positive then

A

the axis is likely to be normal

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34
Q

If lead II is not positive then

A

then the axis is likely to be abnormal - have to work out if it is right and left deviation

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35
Q

What do you do if lead II is not positive

A
  • If lead II is not positive you have to work out if it is right or left axis deviation
  • then you look at lead III
  • if lead III is negative then it is left axis deviation
  • if lead III is positive then look at lead I
  • if lead I is negative then you have right axis deviation
36
Q

right axis deviation can be a…

A

normal variant whereas left axis deviation is always abnormal

37
Q

What can cause right axis deviation

A

– children and tall thin adults
– RVH
– chronic lung disease/ pulmonary embolus
– left posterior hemiblock
– atrial septal defect/ ventricular septal defect
– Wolff-Parkinson-White syndrome - left sided accessory pathway

38
Q

What can cause left axis deviation

A

– LVH
– LBBB and left anterior hemiblock
– Q waves of inferior myocardial infarction
– Wolff-Parkinson-White syndrome - right sided accessory pathway

39
Q

What leads is it best to look at P wave morphology

A

Leads I and II

40
Q

What causes P pulmonale

A
  • peaked P wave

- Right atrial hypertrophy (tall and thin)

41
Q

What causes P mitrale

A
  • Bifid P wave

- Left atrial hypertrophy (M shape)

42
Q

What is the normal PR length

A
  • Normal PR = 120-200 msec

* Normal 3-5 small Sq

43
Q

What are the types of heart block

A

– 1st degree
– 2nd degree (Mobitz I and II)
– 3rd degree or Complete heart block

44
Q

what does the ECG look like in bundle branch block

A
  • PR normal
  • QRS > 120 msec
  • LBBB and RBBB
45
Q

describe 1st degree heart block

A

PR interval is longer than 120msec

46
Q

Describe 2nd degree heart block

A

type 1
- PR interval gradually gets longer until it is no longer followed by a QRS complex

type 2
- PR interval is randomly not followed by a QRS complex

47
Q

Describe 3rd degree heart block

A
  • When the P wave doesn’t correspond with the QRS wave at all
  • AV dissociation
48
Q

what is wolf parkinson white syndrome associated with

A
  • pre excitation through an accessory pathway
49
Q

What does an ECG of wolf parkinsons white syndrome look like

A
  • Short P-R interval
  • delta wave
  • Wide QRS complex
50
Q

What does supra-ventricular tachycardia look like on an ECG

A
  • Regular
  • Narrow complex tachycardia
  • No P waves or atrial activity
51
Q

What is the normal QRS duration

A

Normal range < 120 msec/ 3 small Sq

52
Q

How do you tell left and right bundle branch block

A

WiLLiaM morphology
- William - if you get a W pattern around V1/V2 and an M pattern around V5/V6 then it is left bundle branch block

MaRRoW
- if you get a M around V1/V2 and W around V5/V6 then it is a right bundle branch block

53
Q

What does left ventricular hypertrophy look like on an ECG

A
  • Large QRS voltages
  • Any V or S > 25mm
  • Combined R and S > 35mm
  • aVL or I > 13 mm
54
Q

What is left ventricular hypertrophy associated with

A
  • Strain pattern of ST depression and T wave inversion
55
Q

what leads look at which part of the wall

  • inferior
  • anterior
  • lateral
A
  • inferior - II/III/aVF
  • anterior - V2-4
  • lateral - V5-6/I/aVL
56
Q

What are the ECG changes with myocardial infarction

A
  • Peaked T waves (minutes before)
  • ST elevation ( minutes-hours after)
  • ST depression
  • Q waves (hours after to a few days - can persist but may resolve)
  • inverted T waves - hours may reverse or may be permanent
57
Q

What do you divide MI into

A

STEMI

NSTEMI

58
Q

Wellens syndrome

A

Antero-lateral T wave inversion

  • anterior NSTEMI pending troponin
  • LAD syndrome - LAD can involve the lateral wall as well as the anterior wall
  • this patient should be treated as an MI
  • Sign of an LAD lesion
59
Q

How do you define Atrial Fibrillation

A

disordered electrical activity

60
Q

What does an ECG look like in atrial fibrillation

A
  • Irregularly irregular ventricular rhythm

- No P waves

61
Q

Define what happens in atrial flutter

A

Re-entrant circuit in RA Flutter rate 300 bpm

62
Q

describe what an ECG looks like in atrial flutter

A
  • flutter waves
  • regular rate
  • V rate depends on the degree of transmission of F waves
63
Q

What is the flutter rate in atrial flutter

A

300bpm

64
Q

describe atrial tachycardai

A
  • abnormal focus of atrial depolarisation -
    abnormal P wave morphology
  • Unexplained tachycardia
65
Q

name a type of SVT

A
  • AVNRT - atrio ventricular node re-entrant tachycardia
66
Q

describe an SVT

A
  • Accessory pathway in AV node

- Leads to SVT

67
Q

a broad complex tachycardia is a

A

VT until proven otherwise

68
Q

define atrial flutter waves

A

Saw tooth P wave

69
Q

What do you do when someone has ventricular fibrillation

A
  • disorder ventricular depolarisation
  • person in cardiac arrest
  • perform CPR, give
  • need a defibrillator
70
Q

What ECG changes happen in hypokalaemia

A
  • small T waves
  • Prominent U waves
  • Peaked P waves
71
Q

What ECG changes happen in hyperkalemia

A
  • Tall Tented T waves
  • wide QRS complex
  • Absent P waves
  • Sine wave appearance
72
Q

What ECG changes happen in hypercalcaemia

A
  • short QT interval
73
Q

What ECG changes happen in hypocalcaemia

A
  • long QT interval

- small T waves

74
Q

What can cause a prolonged QT interval

A
  • Congenital – Romano-Ward syndrome, Jervell and Lange-Nielsen syndrome
  • Cardiac – MI, ischaemia, mitral valve prolapse
  • HIV – direct effect of virus or protease inhibitors
  • Metabolic – hypokalaemia, hypomagnesaemia, hypocalcaemia, starvation, hypothyroidism, hypothermia
  • Toxic – organophosphates
  • Anti-arrhythmic drugs – quinidine, amiodarone, procainamide, sotalol
  • Antimicrobials – erythromycin, levofloxacin, pentamide, halofantrine
  • Antihistamines – terfenadine, astimazole
  • Motility drugs – domperidone
  • Psychoactive drugs – haloperidol, risperidone, TCAs, SSRIs
  • Connective disease disorders – Anto-RO/SSA Abs
  • Herbalism – Chinese folk remedies (arsenic), cocaine, quinine, artemisinins (antimalarials)
75
Q

What can cause a short QT interval

A

hypercalcaemia

76
Q

When is a T wave peaked

A

hyperkalameia

77
Q

When is a T wave flattened

A

hypokalaemia

78
Q

What can cause AF

A
  • IHD
  • thyrotoxicosis
  • hypertension
  • obesity
  • CCF
  • alcohol
79
Q

What are the causes of 1st and 2nd degree heart block

A
  • normal variant
  • athletes
  • sick sinus syndrome
  • IHD
  • acte myocarditis
  • drugs - digoxin and beta blockers
80
Q

What are the causes of 3rd degree heart block

A
  • IDH
  • idiopathic (fibrosis)
  • congenital
  • aortic valve calcification
  • cardiac surgery/trauma
  • digoxin toxicity
  • infiltration (abscesses, granulomas, tumours, parasites)
81
Q

What does digoxin look like

A
  • Down-sloping ST depression
  • T wave inversion in V5-V6
  • any arrhythmia may occur
82
Q

What does right bundle branch block look like

A
  • QRS >0.12s
  • V1: ‘RSR’ pattern, dominant R
  • V1-V3 or V4: T-wave inversion
  • V6: wide, slurred S-wave
83
Q

What does left bundle branch block look like

A
  • QRS > 0.12s
  • V5 - M pattern
  • V1 - dominant S
  • I, aVL, V5-V6: T wave inversion
84
Q

What is bifasciular block

A

LBBB+RBBB: manifests as an axis deviation

85
Q

What is trifascicular block

A

bifasciular block + 1st degree Heart block

86
Q

What does left ventricular hypertrophy look like

A

R-wave in V6 >25mm OR sum of S-wave in V1 and R-wave in V6 >35mm

87
Q

What does right ventricular hypertrophy look like

A

Dominant R-wave in V1, T-wave inversion in V1-V3 or V4, deep S-wave in V6, RAD

Year 3 - CR (44 decks)

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