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Year 3 - CR > Interpretation of ECG > Flashcards

Interpretation of ECG Flashcards

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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
What is the difference between supra-ventricular and ventricular ectopics
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
26
What is the normal heart rate
50-100bpm
27
How do you calculate heart rate
- 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
28
who can you not calculate heart rate in
- Patients who have an irregular heart rhythm
29
What is the axis
Axis is the net electrical vector of the heart | - gives an overall idea of the direction of depolarisation
30
in what direction does the heart depolarise
- from the top of the right shoulder and down | - from aVR to II
31
What is the normal electrical axis
-30 to +120
32
what is the axis in left axis deviation and right axis deviation
Left axis deviation is when the axis is greater than -30 right axis deviation is when the axis is greater than +120
33
if lead II is positive then
the axis is likely to be normal
34
If lead II is not positive then
then the axis is likely to be abnormal - have to work out if it is right and left deviation
35
What do you do if lead II is not positive
- 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
right axis deviation can be a...
normal variant whereas left axis deviation is always abnormal
37
What can cause right axis deviation
– 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
What can cause left axis deviation
– LVH – LBBB and left anterior hemiblock – Q waves of inferior myocardial infarction – Wolff-Parkinson-White syndrome - right sided accessory pathway
39
What leads is it best to look at P wave morphology
Leads I and II
40
What causes P pulmonale
- peaked P wave | - Right atrial hypertrophy (tall and thin)
41
What causes P mitrale
- Bifid P wave | - Left atrial hypertrophy (M shape)
42
What is the normal PR length
* Normal PR = 120-200 msec | * Normal 3-5 small Sq
43
What are the types of heart block
– 1st degree – 2nd degree (Mobitz I and II) – 3rd degree or Complete heart block
44
what does the ECG look like in bundle branch block
* PR normal * QRS > 120 msec * LBBB and RBBB
45
describe 1st degree heart block
PR interval is longer than 120msec
46
Describe 2nd degree heart block
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
Describe 3rd degree heart block
- When the P wave doesn't correspond with the QRS wave at all - AV dissociation
48
what is wolf parkinson white syndrome associated with
- pre excitation through an accessory pathway
49
What does an ECG of wolf parkinsons white syndrome look like
- Short P-R interval - delta wave - Wide QRS complex
50
What does supra-ventricular tachycardia look like on an ECG
- Regular - Narrow complex tachycardia - No P waves or atrial activity
51
What is the normal QRS duration
Normal range < 120 msec/ 3 small Sq
52
How do you tell left and right bundle branch block
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
What does left ventricular hypertrophy look like on an ECG
- Large QRS voltages - Any V or S > 25mm - Combined R and S > 35mm - aVL or I > 13 mm
54
What is left ventricular hypertrophy associated with
- Strain pattern of ST depression and T wave inversion
55
what leads look at which part of the wall - inferior - anterior - lateral
- inferior - II/III/aVF - anterior - V2-4 - lateral - V5-6/I/aVL
56
What are the ECG changes with myocardial infarction
- 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
What do you divide MI into
STEMI | NSTEMI
58
Wellens syndrome
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
How do you define Atrial Fibrillation
disordered electrical activity
60
What does an ECG look like in atrial fibrillation
- Irregularly irregular ventricular rhythm | - No P waves
61
Define what happens in atrial flutter
Re-entrant circuit in RA Flutter rate 300 bpm
62
describe what an ECG looks like in atrial flutter
- flutter waves - regular rate - V rate depends on the degree of transmission of F waves
63
What is the flutter rate in atrial flutter
300bpm
64
describe atrial tachycardai
- abnormal focus of atrial depolarisation - abnormal P wave morphology - Unexplained tachycardia
65
name a type of SVT
- AVNRT - atrio ventricular node re-entrant tachycardia
66
describe an SVT
- Accessory pathway in AV node | - Leads to SVT
67
a broad complex tachycardia is a
VT until proven otherwise
68
define atrial flutter waves
Saw tooth P wave
69
What do you do when someone has ventricular fibrillation
- disorder ventricular depolarisation - person in cardiac arrest - perform CPR, give - need a defibrillator
70
What ECG changes happen in hypokalaemia
- small T waves - Prominent U waves - Peaked P waves
71
What ECG changes happen in hyperkalemia
- Tall Tented T waves - wide QRS complex - Absent P waves - Sine wave appearance
72
What ECG changes happen in hypercalcaemia
- short QT interval
73
What ECG changes happen in hypocalcaemia
- long QT interval | - small T waves
74
What can cause a prolonged QT interval
- 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
What can cause a short QT interval
hypercalcaemia
76
When is a T wave peaked
hyperkalameia
77
When is a T wave flattened
hypokalaemia
78
What can cause AF
- IHD - thyrotoxicosis - hypertension - obesity - CCF - alcohol
79
What are the causes of 1st and 2nd degree heart block
- normal variant - athletes - sick sinus syndrome - IHD - acte myocarditis - drugs - digoxin and beta blockers
80
What are the causes of 3rd degree heart block
- IDH - idiopathic (fibrosis) - congenital - aortic valve calcification - cardiac surgery/trauma - digoxin toxicity - infiltration (abscesses, granulomas, tumours, parasites)
81
What does digoxin look like
- Down-sloping ST depression - T wave inversion in V5-V6 - any arrhythmia may occur
82
What does right bundle branch block look like
- QRS >0.12s - V1: ‘RSR’ pattern, dominant R - V1-V3 or V4: T-wave inversion - V6: wide, slurred S-wave
83
What does left bundle branch block look like
- QRS > 0.12s - V5 - M pattern - V1 - dominant S - I, aVL, V5-V6: T wave inversion
84
What is bifasciular block
LBBB+RBBB: manifests as an axis deviation
85
What is trifascicular block
bifasciular block + 1st degree Heart block
86
What does left ventricular hypertrophy look like
R-wave in V6 >25mm OR sum of S-wave in V1 and R-wave in V6 >35mm
87
What does right ventricular hypertrophy look like
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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