ECG

Question 1

What does L axis deviation mean from the pathological (simple) point of view?

Answer 1

L axis deviation = more electricity goes to the L side of the hear

Question 2

How does L axis deviation look on ECG?

Answer 2

L = leaving (positive in lead I and negative in lead II) = point away from each other

Question 3

Causes for L axis deviation

Answer 3

L axis deviation = increased electricity to L side of the heart

Causes:

• L ventricular hypertrophy
• Wolf-Parkinson White syndrome
• VT
• LBBB
• inferior MI
• L anterior hemiblock

Question 4

How does R axis deviation look like on ECG?

Answer 4

R = returning (lead I is negative and lead II is positive) -> the ways point towards each other

Question 5

What R axis deviation mean and what are possible causes?

Answer 5

R axis deviation = more electricity goes towards R side of the heart

Causes: tall and thin body type, RV hypertrophy (e.g. in PE, pulmonary disease), lateral MI, WOlf-Parkinson White Syndrome)

Question 6

How high P wave should be?

What does it mean if it is higher than that?

Answer 6

P wave should be =/< 2 small squares

If it is higher than that -> R atrial enlargement e.g. in pulmonary hypertension

Question 7

What are possible pathological appearances of P wave? (morphology)

Answer 7

• bifid
• peaked

Question 8

How does bifid P wave looks like?

Answer 8

Bifid

looks like ‘m’ = P mitrale (left atrial enlargement - caused by mitral stenosis)

Question 9

How does ‘peaked’ P wave look like? What is its cause?

Answer 9

Peaked = P pulmonare

*classically seen in R atrial enlargement in lung disease

Question 10

What’s the normal length of PR interval?

Answer 10

PR interval should be 3-5 small squares

Question 11

When PR interval is decreased?

Answer 11

PR interval decreased in: accessory conduction pathways (e.g. WPW syndrome)

Question 12

When PR interval is increased?

Answer 12

PR interval increased in AV node block (‘heart block’)

Question 13

Causes of heart block

Answer 13

• athletes /increased vagal tone
• electrolyte disturbances
• Drugs that block AV node: B - blockers, digoxin, CCB
• conduction system fibrosis
• Inferior MI
• autoimmune disease (SLE, systemic sclerosis)
• inflammatory diseases (myocarditis, RF)
• infiltrative conditions (amyloidosis, haemochromatosis)

Question 15

Size of normal Q wave

Answer 15

Normal Q waves = small Q wave:

• <1 small square wide
• <2 small squares deep

Question 16

What leads normal Q waves can be found in?

Answer 16

Normal Q wave (small; <1 sq wide, <2 sq deep)

Found in: I, aVL, and V6 -> due to septal depolarization

Question 17

What do pathological Q waves mean?

Answer 17

Established/previous full thickness MI

Question 18

What is a normal R wave progression across ECG?

Answer 18

Negative in V1 (dominant S wave) -> mostly positive in V6 (dominant R)

Question 19

What’s transition point?

Answer 19

Leads where R and S are equal -> usually V3/V4

Question 20

What’s the clockwise rotation and what’s its cause?

Answer 20

Clockwise rotation = transition point after V4

Cause: R ventricular hypertrophy e.g. in chronic pulmonary disease

Question 21

What’s ‘M’ pattern in bundle blocks?

Answer 21

RSR’

Question 22

Potential causes of RBBB

Answer 22

RBBB:

• R ventricular hypertrophy
• cor pulmonare
• PE
• atrial-septal defect
• IHD
• cardiomyopathy

Question 23

Possible causes for LBBB

Answer 23

• aortic stenosis
• IHD
• hypertension
• anterior MI
• cardiomyopathy
• conduction system fibrosis
• hypercalcaemia

Question 24

Pattern seen on LBBB

Answer 24

W illia M

W on V1

M on V6

Question 25

Pattern seen on RBBB

Answer 25

M arro W M - V1 W - V6

Question 26

What is the disgnosis if: RSR' pattern seen with a normal QRS length?

Answer 26

Partial (incomplete) bundle branch block - no clinical significance (normal QRS length is \<3 sq)

Question 27

ST segment elevation: * convex or straight * concave * concave/saddle shaped **Causes**

Answer 27

* **Convex/ straight** -\> infraction * **concave** -\> early repolarisation, LVH * **saddle shaped** -\> pericarditis, tamponade

Question 28

What does ST elevation that is downwards slopping/ 'reverse tick' mean?

Answer 28

Digoxin toxicity

Question 29

In which leads T inversion is normal?

Answer 29

It can be normal in leads: **III, aVR** and **V₁ **(right leads) ## Footnote This is due to the angle from which they view the heart Also, in Afro-Caribbean: **V₂-₃**

Question 30

T inversion in leads other than normally seen - causes

Answer 30

- ischaemia/post MI - PE - RL ventricular hypertrophy - bundle branch block - digoxin use

Question 31

What does **tented T wave** mean?

Answer 31

hyperkalemia

Question 32

What do **flat T waves** mean?

Answer 32

hypokalaemia

Question 33

Biphasic T wave - cause

Answer 33

**Biphasic** - ischaemia (up then down) - hypokalaemia (down then up)

Question 34

Regions on ECG

Answer 34

Question 35

Corrected QT interval ## Footnote - value - how to calculate - significance

Answer 35

\<450 ms - calculated by ECG machine or by use of online calculator - if it is increased -\> predisposition to polymorphic VT

Question 36

Causes of prolonged QT inerval

Answer 36

- congenital syndromes - antipsychotics - sotalol/amiodarone (class III) - TCAs - macrolides - hypokalaemia/hypomagnesaemia/ hypocalcaemia

Question 37

Causes of U waves

Answer 37

- can be normal - hypothermia - hypokalaemia - use of anti-arrhythmia

Question 38

The sequence of ECG interpretation

Answer 38

* Personal details: name, DOB * Date * Symptoms (e.g. chest pain) * calibration * Rate and rhythm * Axis * P wave * PR interval * QRS complex * ST segment * T wave * Other things: corrected QT interval, U waves

Question 39

Pathological changes on ECG in STEMI (in order)

Answer 39