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ECGs Flashcards

1
Q

State the exact correct location for each chest lead

A

V1: 4th intercostal space, right sternal edge
V2: 4th intercostal space, left sternal edge
V3: halfway between V2 and V4
V4: 5th intercostal space, mid clavicular line
V5: same level as V4, anterior axillary line
V6: same level as V4, mid axillary line

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2
Q

State 3 common tracing problems

A

muscle tremor
AC interference
baseline wander

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3
Q

How should the patient be positioned for an ECG

A

lying at 30 degrees

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4
Q

What is the scale of the ECG tracing:

a) in time horizontally
b) in voltage vertically

A

a) 1 small box = 0.04s, 1 big box 0.2s

b) 1cm = 1mV

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5
Q

How would you calculate the HR in

a) sinus rhythm
b) sinus tachycardia
c) irregular rhythm

A

a) 300 / number of big boxes between R waves
b) 1500 / number of small boxes between R waves
c) number of QRS complexes in 30 big boxes (6s) x 10

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6
Q

Starting at 12, go through the leads clockwise in where they measure the heart’s electrical impulses from

A 
aVL (2 o'clock)
lead I (3 o'clock)
lead II (5 o'clock)
aVF (6 o'clock)
lead III (7 o'clock)
aVR (10 o'clock)
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7
Q

State what will be seen on the ECG in left axis deviation

A

lead I will be positive, aVF will be negative

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8
Q

State what will be seen on the ECG in right axis deviation

A

lead I will be negative, aVF will be positive

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9
Q

What is considered a normal PR interval?

A

120-200ms (3-5 small boxes)

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10
Q

What must the duration of the QRS complex be for it to be considered normal?

A

<120ms (3 small boxes)

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11
Q

How is the “correct” QT interval for a patient calculated?

A

QT interval in seconds / square root of RR interval in seconds
AKA Bazett formula

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12
Q

Where is the PR interval measured from - to?

A

start of P wave to the start of the QRS complex

(from the start of atrial depolarisation to the start of ventricular depolarisation - represents AV nodal delay to allow ventricular filling)

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13
Q

a) What is meant by R wave progression?

b) what is meant by R wave transition?

A

a) The R wave gradually increasing in size across the chest leads
b) the R wave becoming larger than the S wave (should happen in V4)

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14
Q

What is a supraventricular rhythm?

A

Any rhythm originating above the AV node (where conducted through it or not)

Therefore likely narrow QRS complex

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15
Q

What is sinus arrhythmia and what is it likely caused by?

A

ECG meets criteria for sinus rhythm but the rhythm itself is irregular

likely caused by respiration (due to the increased vagal tone)

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16
Q

What is AF and how is it characterised on an ECG?

A

disorganised electrical activity in atria (therefore impulse no longer SA node throughput atria to AV node)

Characterised by the irregularly irregular rhythm

will see ragged baseline and absent P waves

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17
Q

Atrial Flutter

a) What is it caused by?
b) What can the HR be?
c) What is the characteristic “sawtooth” best seen?

A

a) re-entry circuit within the atria
b) since the atria are beating at 300 bpm, likely a divisible of 300 I.e. 150, 100, 75

NOTE: may witness irregular rhythm due to “variable AV block” however multiple of 300 will be see in other R-R intervals

c) leads II and V1

18
Q

Junctional rhythm

a) what is it?
b) what will be seen on ecg?

A

a) electrical impulses start at AV rather than SA node meaning electrical impulses travel across atria (backwards) and ventricles simultaneously
b) inverted P wave after the QRS complex

19
Q

What will be seen on an ECG on a patient with superventricular ectopics?

A

Sinus rhythm

HOWEVER different P wave morphologies will be seen (wave looks different) and this beat will come early

20
Q

What will be seen in ventricular rhythms?

NOTE: these are always pathological

A

Wide QRS (>120ms)

21
Q

For ventricular premature complexes (ectopics), what is meant by

a) bigeminy
b) trigeminy

A

a) 1 sinus beat followed by 1 ventricular premature complex

b) 1 sinus beat followed by 2 ventricular premature complexes

22
Q

What is the difference between monomorphic and polymorphic VT?

A

monomorphic - each wide QRS complex looks the same

polymorphic - each complex looks different and therefore can be difficult to differentiate from VF

23
Q

What can you use to help determine whether an ECG is showing AF + BBB (AKA aberrancy) or VT?

A
  • look at the history
  • slow down HR usual vagal manoeuvre or adenosine

I.e. previous BBB?
or if previous coronary disease side more towards VT

24
Q

Describe each type of heart block

a) first degree
b) second degree
i) mobitz type 1
ii) mobitz type 2
c) third degree

A

a) prolonged PR interval

b) i) PR interval gradually increases before eventual drop of QRS complex - only treated if presence of collapse or haemodynamic compromise
ii) constant PR interval with every 2nd/3rd QRS complex missed - pathological and needs intervention

c) no relationship between P waves and QRS complexes (which will be broad as they created by ventricular escape rhythm)

25
What is the escape phenomenon?
all of the heart has its own automaticity if needed I.e. can make its own electrical impulse This provides back up in complete heart block and shows wide QRS complexes at rate of 30-40 bpm
26
Fasicular block a) what are the fasicles? b) what can be seen in i) bifasicular block (blockade of 2 fasicles) ii) trifasicular block
a) - AV node - right bundle branch - left anterior branch - left posterior branch b) i) two of: - prolonged PR interval - RBBB - left axis deviation ii) - prolonged PR interval - RBBB - left axis deviation OR alternating between LBBB and RBBB
27
What is the treatment for circulatory collapse due to complete heart block?
IV atropine and isoprenaline until transvenous pacing wire insertion can be undertaken
28
In what leads will ECG changes be seen with ischaemia / infarction to the following areas: a) anterior b) lateral c) inferior
a) V1-4 b) I, aVL, V5+6 c) II, III, aVF
29
What ECG changes can be seen in ischaemia?
T wave changes - tall ( remember normally should be no more than 1/2 of QRS) - biphasic - inverted - flattened ST depression
30
What is the ECG criteria for thrombolysis?
ST elevation in: two contiguous limb leads > 1mm OR two contiguous chest leads >2mm
31
Q waves in infarction a) When do they develop? b) Define pathological Q waves
a) 2-24 hrs after b) - any Q wave in leads V1-3 - Q wave =/> 0.03s in leads I, II, aVL, aVF and V4-6 NOTE lead III can often show a Q wave physiologically and aVR not related to a vascular territory
32
What other than infarction can cause `ST elevation?
- Benign early repolarisation - LBBB - LVH - Ventricular aneurysm - Coronary Vasospasm / Printzmetal's angina - Pericarditis - Brugada syndrome - Subarachnoid haemorrhage
33
What will be seen on an ECG in posterior MI?
Changes in V1-3: - ST depression - tall broad R waves - prominent R wave in V2 OR if posterior MI suspected can add 3 leads to the posterior chest wall in line with V6 These will show ST elevation and Q waves
34
What is meant by partial / incomplete bundle branch block?
Pattern of bundle branch block exists on ECG but QRS complex <0.12s
35
Right bundle branch block a) What will be seen on ECG? b) What sign of MI will still be seen as normal?
a) - RSR complex in V1 - M shape in V1 and W shape in V6 - S wave >0.12s in V4-6 NOTE: WilliaM MorroW - however, notch might not always be present may just be the general direction I.e. m = upward deflection from isoelectric line w = downward deflection b) pathological Q wave
36
Left Bundle Branch Block What can be seen on ECG?
- prolonged QRS - notched QRS (M-shaped) leads I, aVL, V5+6 - wide, notched QS complexes in V1 NOTE: WilliaM MorroW
37
Left hemiblock a) What is seen in i) left anterior hemiblock ii) left posterior hemiblock b) Which is more common?
a) i) - left axis deviation - R waves in inferior leads ii) - right axis deviation b) anterior hemiblock - > this is because posterior region of heart has dual blood supply from LAD and PDRCA
38
How can you tell the difference between the escape phenomenon and ectopic beats on an ECG?
Both will appear as wide QRS complexes, however an ectopic beat comes before the next beat would be expected as it an abnormal rhythm generated from elsewhere whereas the escape phonemon is a survival mechanism taking place if no regular beat has taken place hence will be after a regular beat would have been expected
39
Pericarditis a) What clinical feature are seen? b) What ECG changes are seen?
a) - secondary to MI or viral infection - pleuritic chest pain - fever - pericardial friction rub (a grating, to-and-fro sound produced by friction of the heart against the pericardium heard best over left sternal border during inspiration) b) - concave ST elevation involving >1 vascular territory - PR depression NOTE: these changes will not evolve over time they will be constant
40
What can cause right axis deviation?
- RBBB - RV Hypertrophy / cor pulmonale - dextrocardia - WPW - osmium secundum ASD - left posterior hemiblock - ventricular ectopi NOTE: can also be normal or caused by inspiration mnemonic the rights - block, hypertrophy, heart on the right WPW - WPW, posterior hemiblock, wentricular ectopi
41
What can cause left axis deviation?
- LBBB - left anterior hemiblock - WPW - congenital lesions: osmium primum ASD, tricuspid atresia - emphysema - hyperkalaemia NOTE: can also be seen on expiration mnemonic lefts congenital something wrong with lungs, something wrong with kidneys
42
What can cause a) LBBB b) RBBB
a) - hypertension - ischaemic heart disease - MI - cardiomyopathy mnemonic: first 3 is gradual worsening progression of CV disease b) - pulmonary hypertension (causes include PE, COPD) - right sided HF (cor pulmonale) (can be caused by pulmonary hypertension) - ischaemic heart disease - MI - cardiomyopathy

Cardio (14 decks)

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