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CR3 > Interpretation fo ECGs > Flashcards

Interpretation fo ECGs Flashcards

(64 cards)

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1
Q

Electrical conduction of the heart

A

SAN -> AVN -> Bundle of His -> L & R bundle branches -> Purkinje fibres

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2
Q

Where does the left bundle branch conduct to?

A

Left posterior fascicle
Septal fascicle
Left anterior fascicle

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3
Q

What does the P wave represent?

A

atrial depolarisation

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4
Q

What does the QRS complex represent?

A

ventricular depolarisation

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5
Q

What does the T wave represent?

A

ventricular repolarisation

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6
Q

What should you look at first when you look at an ECG?

A

Check it is the right person - name, DOB, hospital number

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7
Q

What should you do second when you look at an ECG?

A

Assess calibration

  • paper speed = 25mm/sec
  • calibration = 1mV=10mm
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8
Q

Position of 6 chest leads

A 
V1 = 4th ICS RHS
V2 = 4th ICS LHF
V3 = 5th rib LHS
V4 = 5th ICS LHS, mid clavicular line, apex beat
V5 = between 4 and 6
V6 = mix axillary line
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9
Q

Which leads should be positive?

A

Lead II
avF
> Lead III

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10
Q

Which leads should be negative?

A

avR

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11
Q

What are your 6 standard leads?

A

avR,L,F

leads 1,2,3

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12
Q

How much does 1 small square represent?

A

40msec

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13
Q

How much does 1 big square represent?

A

200 msec

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14
Q

How long is the PR interval?

A

3-5 small sq

120-200 msec

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15
Q

How long is the QRS duration?

A

<3 small sq

<120 msec

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16
Q

How long is the QT interval?

A

<440 msec

dependent on HR so sometimes corrected

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17
Q

How to read an ECG?

A
  • confirm patient
  • confirm calibration
  • comment of rhythm
  • rate
  • axis
  • P waves
  • PR interval/heart block
  • QRS morphology/ST segments/T waves
  • QT interval
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18
Q

What to do if there is no electrical activity?

A
  • check patient is well
  • are leads connected
  • check for interference (phones/chargers)
  • check calibration is correct
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19
Q

How to assess rhythm/

A
  • are QRS complexes regular?

- is there a P wave before every QRS = sinus rhythm

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20
Q

What is the definition of sinus rhythm?

A

Presence of P wave before every QRS

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21
Q

What is a rhythm strip?

A

Normally in lead II or I as good to look at QRS

10 second strip on 1 lead

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22
Q

Who gets sinus arrhythmia?

A

Young
Good vagal tone
Athletes
Deep slow respirations

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23
Q

What are ectopics?

A

When heart throws off extra beats

  • above AVN = supra-ventricular ectopics
  • below AVN = ventricular ectopics
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24
Q

How can you differentiate between ectopics?

A
  • supraventricular = narrow QRS complex = above AVN

- ventricular = broad QRS complex = below AVN

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25
How to comment on HR?
- normal is 50-100 - count number of big squares between QRS complexes - divide 300 by no. of big squares - not to use if irregular rhythm
26
What is the axis of the heart?
The electrical vector of the heart | Direction of depolarisation
27
What is the general normal direction of depolarisation?
From aVR -> II | From top of right shoulder diagonally down to left
28
What is the normal axis?
-30 to +120
29
What is L axis deviation?
Axis more negative than -30 | Anticlockwise
30
What is R axis deviation?
Axis > +120 | Clockwise
31
When is the axis abnormal and when is there deviation?
Lead II negative = abnormal Lead III negative = LAD Lead I negative = RAD
32
Causes of RAD?
``` Children Tall thin adults RVH PE/chronic lung disease L. posterior hemiblock ASD/VSD Wolff Parkinson White Syndrome (L. accessory pathway) ```
33
Causes of LAD?
LVH LBBB of L. anterior hemiblock Q waves of inferior MI Wolff Parkinson White Syndrome (R. sided accessory pathway)
34
How to assess P wave morphology?
- lead II or I - P mitrale = looks like an M = due to L atrial hypertrophy - P pulmonale = tall and thin = R atrial hypertrophy
35
What is the PR interval?
Delay from SAN to AVN conduction
36
Normal PR interval
120-200msec | 3-5 small sq
37
Types of heart block
1st degree 2nd degree (Mobits type 1 and 2) Complete heart block
38
Bundle branch block
PR normal QRS >120 msec Delay in ventricular repolarisation L or R
39
2nd degree heart block Mobitz type 1 (wenkebach)
Progressive increase in PR interval | Followed by non-conducted QRS
40
2nd degree heart block Mobitz type 2
Non conducted QRS after every 2nd P wave | Broad QRS complex
41
Complete heart block
P waves unrelated to QRS | A-V dissociation/loss of conduction
42
Wolf Parkinson White Syndrome
Short PR interval Wide QRS Delta wave Pointy QRS Pre-excitation through accessory pathway
43
Supra-ventricular tachycardia
Regular Narrow complex tachycardia No P waves or atrial activity Caused by an eddie
44
LBBB
``` WiLLiaM morphology W pattern around V1,2 M pattern around V5,6 QRS >120/3 small sq LAD ```
45
RBBB
``` QRS >120 MaRRoW morphology M around V1,2 W around V5,6 RAD ```
46
LVH
- large QRS voltages! | - may have ST depression and T wave inversion
47
What leads look at the lateral wall?
V5,6 lead I aVL
48
What leads look at the anterior wall?
V2,3,4
49
What leads look at the inferior wall?
Leads 2,3 | aVF
50
ECG changes associated with MI
- MINUTES = peaked T waves - MINS TO HOURS = ST elevation (if STEMI) or depression (NSTEMI) - HOURS = Q waves, inverted T waves
51
Old infarction
T wave inversion | Antero-lateral Q waves
52
Wellens Syndrome
Very deep T wave inversion LAD syndrome Probable antero-lateral NSTEMI High risk patient
53
AF
No P waves | Irregularly irregular ventricular rhythm
54
Atrial Flutter
``` Re-entrant circuit in RA Flutter rate = 300bpm HR = 150bpm Regularly irregular Flutter wave = give saw tooth pattern on ECG ```
55
Atrial tachycardia
- abnormal focus of atrial depol - abnormal P wave morphology - unexplained tachycardia
56
AVNRT
Atrio-ventricular node re-entrant tachycardia Accessory pathway in AVN Leads to SVT Eddie current Depol and Repol same tissue again and again
57
Broad complex tachycardias
VT (emergency) SVT (with abnormal conduction) WPW via accessory pathway ALLWAYS CONSIDERED VT UNTIL PROVEN OTHERWISE
58
Ventricular Fibrillation
Abnormal QRS waves Patient in arrest not conscious Need defib
59
Regular tachy rhythms
Sinus SVT Flutter VT
60
Regular brady rhythms
Sinus | CHB
61
Irregular tachy rhythms
AF | Sinus with multiple ectopics
62
Irregular brady rhythms
AF overuse beta blockers | Exaggerated sinus
63
Narrow QRS complex rhythms
Sinus AF Flutter SVT
64
Broad QRS complex rhythms
VT SVT with BBB CHB

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