ECGs Flashcards by Beth Spurrier

How do you calculate HR on ECG?

300/no. of large squares between R-intervals

If pulse irregular: total R waves on ECG X 6

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What HR counts as sinus bradycardia?

<60bpm

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What HR counts as sinus tachycardia?

> 100bpm

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How do you check the regularity of HR?

mark 4 R peaks on a piece of paper, move along trace to confirm

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How do you check that an ECG is in sinus rhythm?

look for a P before every QRS complex

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What are the two common features of AF on an ECG?

no clear P waves

Irregular QRS complex

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Which arrhythmia presents with a ‘sawtooth’ baseline?

atrial flutter

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What arrhythmias may present with broad-complex tachycardia with no p waves?

VF
VT

sometimes SVT with BBB/WPW

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What are key features of SVT?

narrow complex tachycardia

abnormal or no P waves

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How can you confirm that an ECG does not have any axis deviation?

QRS complexes in lead I and II are predominantly positive

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How can you identify left-axis deviation?

R waves point away from each other in leads I and II

QRS predominantly +ve in lead I and negative in lead II

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What are some common causes of L-axis deviation?

LV hypertrophy/strain
L anterior hemiblock
Inferior MI
WPW
VT

(anything where more electricity is going towards left)

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How can you identify right-axis deviation?

R waves point towards each other in leads I and II

QRS predominantly -ve in lead I and positive in lead II

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What are some common causes of R-axis deviation?

tall, thin body type
RV hypertrophy/strain eg. PE
L posterior semi-block
lateral MI
WPW

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How tall should a P-wave be?

<=2 small squares

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What might cause a raised p wave?

right atrial hypertrophy (caused by pulmonary hypertension or tricuspid stenosis)

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How long should the PR interval be?

3-5 small squares

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What can cause an increase in PR interval?

AV block ‘heart block’

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How can you identify 1st degree AV block?

PR>5 small squares and regular

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What are the different types of 2nd degree AV block?

Mobitz type 1 (Wenkebach)

Moritz type 2 - 2nd degree AV block with 2:1/3:1/4:1 block

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What are the features of Mobitz type 1 heart block (Wenkebach)?

PR progressively elongates until there is failure of conduction of an arterial beat
(then cycle repeats)

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What are the features of Mobitz type 2?

constant normal PR interval
Occasional dropped ventricular beats
(constant ratios: 2:1/3:1/4:1)

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What is third degree heart block commonly known as?

complete heart block

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What are the features of 3rd degree heart block?

complete dissociation between p waves and QRS complexes

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What are some causes of 1st and second degree AV block?

``` increased vagal tone/athletes coronary artery disease myocarditis acute rheumatic carditis digoxin toxicity electrolyte disturbances ```

What are some causes of 3rd degree heart block?

fibrosis around bundle of His caused by ischaemia, congenital, idiopathic, aortic stenosis or trauma) or block of both bundle branches

How should R waves progress?

QRS complexes should progress from mostly negative in V1, to completely positive in V6

How big should a QRS segment be?

<3 small squares

What can cause an increase in QRS complex length?

bundle branch block

How can you identify RBBB?

QRS in V1: M pattern | QRS in V6: W pattern

How can you identify LBBB?

QRS in V1: W pattern | QRS in V2: M pattern

What can cause RBBB?

normal variant atrial septal defect PE

What can cause LBBB?

``` ischaemic disease acute MI cardiomyopathy hypertension aortic stenosis ```

Where should you look to assess QRS complexes?

Chest leads: for R wave progression | Rhythm strip: R wave length

Where should you look to assess QRS height?

V1 and V5/6

How high should a QRS be?

<4 squares

What can cause a R wave > 5 big squares (in V5/6)?

LVH | normal (physically fit pts)

What can cause a dominant wave in V1?

RVH (if there are other signs too eg. T wave inversion in R chest

Where should you check for Q waves?

all leads

What are Q waves a sign of?

Previous MI (but small Q waves can be normal in ! aVL and V6) *Full-thickness MI*

In which leads should you check the ST segment?

All leads

What counts as ST elevation?

increase by >=1 small square

What can ST elevation be a sign of?

Infarction Pericarditis or tamponade if in every lead

What counts as ST depression?

reduction by >=1 small square

What can ST depression be a sign of?

ischaemia | posterior infarction 'reciprocal change'

What are the different types of ST changes (apart from elevation and depression)? What do they suggest?

Saddled: pericarditis/tamponade Upward sloping: normal variant Downward sloping (reverse tick): digoxin toxicity

In which leads should you check the T wave?

All leads

In which leads is T wave inversion normal? Why?

III, aVR and V1 (also V2-3 in black people) Due to the angle from which they look at the heart

What can cause T-wave inversion (in leads where this would not be considered normal)?

ischaemia/post=MI R/L VH Bundle branch block digoxin treatment

What can cause tall-tented T waves?

Hyperkalaemia

What can cause flat T waves?

Hypokalaemia

What should the QT interval be?

<450ms (ECG should calculate this)

What causes increased QT interval? Why is this a problem?

``` Congenital syndromes Anti-psychotics Sotalol/amiodarone TCAs Erythromycin Hypokalaemia Hypomagnesaemia Hypocalcaemia ``` Predisposes to polymorphic VT

Where can U waves be seen? What can cause them?

Rhythm strip Normal or hypkalaemia

What do ST changes in leads II, III and aVF indicate? Which artery is affected?

Inferior MI Right coronary artery

What do ST changes in leads V1 - V4 indicate? Which artery is affected?

Anteroseptal MI LAD artery

What do ST changes in leads V4-V5 and aVL indicate? Which artery is affected?

Anterolateral MI LAD or L circumflex

What do ST changes in leads I, aVL +/- V5-6 indicate? Which artery is affected?

Left circumflex

What would a dominant R wave in V1-V2 and ST depression indicate to you? Which artery would be affected?

Posterior MI Left circumflex or Right coronary

What are key features of AF on an EGG?

Irregular | Without P waves

What are key features of atrial flutter on an ECG?

Regular | Saw-tooth base line (2:1, 3:1 and 4:1 block)

What are key features of atrial tachycardia on an ECG?

Regular | Abnormal P waves

What are key features of VF on an ECG?

no discernable P waves/QRS complexes (random wavy line) NO PULSE

What are key features of VT on an ECG?

Broad complex tachycardia

What are key features of an atrial ectopic on an ECG?

narrow QRS with/without preceding ectopic p wave

What are key features of a ventricular ectopic on an ECG?

abnormal broad QRS at abnormal time | p occurs at predicted time

What are key features of WPW on an ECG?

slurred upstroke into QRS complex Short PR interval QRS complexes may be slightly broad Dominant R wave in V1

What are key features of infarction on an ECG?

ST elevation (first change) T wave inversion Pathological Q waves (signify full-thickness MI)

After what time do pathological Q waves appear?

8-12 hours after ST elevation (if myocardium is not reperfused)

What are the STEMI criteria?

St elevation of >2 small squares in 2 adjacent chest leads ST elevation of >1 small square in 2 adjacent limb leads OR new LBBB

What are key features of ischaemia on an ECG?

ST depression | new T-wave inversion

What are key features of previous infarcts on an ECG?

T wave inversion (weeks-months) Pathological Q waves (permanent)

What are key features of hyperkalaemia on an ECG?

low flat P waves Wide bizarre QRS slurring into ST segment tall-tented T waves

What are key features of hypokalaemia on an ECG?

small flattened T waves Prolonged PR Depressed ST Prominent U wave

What are key features of hypercalcaemia on an ECG?

short QT

What are key features of hypocalcaemia on an ECG?

prolonged QT

What changes to an ECG might a PE cause?

``` tachycardia RV strain (RBBB, right axis deviation) RA enlargement (P pulmonale) ``` S1Q3T3 (prominent S wave in lead I, and Q wave and inverted T wave in lead III) - rare

What ECG changes are associated with pericarditis?

``` ST elevation in all leads PR depression (specific) saddle-shaped ST interval ```

Which leads show septal MI?

V1-2

Which leads show anterior MI?

V3-4

Which leads show lateral MI?

I + aVL | V5-6

Which leads show inferior MI?

II, III and aVF

Which leads show right ventricular MI?

V1 | V4

ECGs Flashcards

(83 cards)