X-rays and ECG

Question 1

What is the structure to interpreting an ECG?

Answer 1

Basics
- name, DOB, time, indication, whether chest pain present, calibration (x -> 25mm/s)

Rate, rhythm, axis

PQRST waveforms

Question 2

Describe rate

Answer 2

Bradycardia < 60
Normal 60-100
Tachycardia > 100

Question 3

Describe rhythm

Answer 3

Count QRS peaks on strip and x 6
Regular or irregular
May be regularly or irregularly irregular

Question 4

Describe axis

Answer 4

Looks at leads I + II

Normal => both +ve
LAD => L eaving each other (away from each other)
RAD => R eturning to each other (facing each other)

Question 5

What do any p-wave abnormalities suggest?

Answer 5

Absent p-waves, irregularly irregular
=> atrial fibrillation

Multiple p-waves per QRS, regularly irregular
=> atrial flutter

Peaked p-waves/M morphology
=> atrial strain due to RHF/LHF

Question 6

What do any QRS abnormalities suggest?

Answer 6

Deep S V1/2 and tall R V5/6 > 7 squares
=> hypertrophy

> 0.12 s QRS
=> BBB/3rd HB

Pathological Q waves; tall and wide
=> previous MI

Question 7

How do you differentiate between L and RBBB?

Answer 7

LBBB
=> WiLLiaM, V1/6

RBBB
=> MaRRoW, V1/6

Question 8

What do any PR interval abnormalities suggest?

Answer 8

Short PR interval, <0.12s
=> ?WPW if delta wave present on upstroke of QRS

Long PR interval, >0.20s
=> 1st degree HB if PR > 5 squares
=> 2nd degree HB
=> 3rd degree HB when there’s also no association between P + QRS (both regular but no link)

Question 9

What are the two types of 2nd degree HB?

Answer 9

Mobitz type 1
=> increasing PR until dropped QRS + repeat

Mobitz type 2
=> randomly dropped QRS every 2/3 p-waves (2:1/3:1)

Question 10

What would the ECG of a hyperkalaemic pt show?

Answer 10

1. Tented T-waves; > 5.5mmol/L
2. Flat p-waves; >6.5mmol/L
3. Broad QRS + bradycardia; > 7.5mmol/L

Question 11

Tx of hyperkalaemia

Answer 11

10ml 10% calcium gluconate/chloride
10U insulin
50ml 50% dextrose

Question 12

What would the ECG of a hypokalaemic pt show?

Answer 12

U waves, ST depression, flattened T-waves, prolonged PR interval, long-QT syndrome

Tx: K+!

Question 13

What do any ST segment abnormalities suggest?

Answer 13

Depression = >/=0.5 mm in >/= 2 contiguous leads

Elevation = >1mm in >/= 2 contiguous limb leads or > 2mm in >/= chest leads

• inferior MI: II, III, aVF; RCA
• lateral MI: I, V5, V6; circumflex
• anterior/septal MI: V1-4; LAD

Question 14

What do any QT interval abnormalities suggest?

Answer 14

Long QT syndrome; >0.44 (m) >0.46 (f)
= acquired: hypomangnesaemia, hypokalaemia, amiodarone
= congenital

Question 15

What do any T wave abnormalities suggest?

Answer 15

Tall; >5mm limb leads + >10mm chest leads
=> hyperkalaemia, hyperacute MI

Inverted (only normal in VI + III)
=> ischaemia, BBB, PE, LVH

Question 16

What would a pneumonia CXR show?

Answer 16

Alveolar shadowing
?Air bronchograms
Usually unilateral

Question 17

What would a pleural effusion CXR show?

Answer 17

Homogenous shadowing
Fluid level (meniscus)
Loss of costophrenic angles
Transudate vs exudate

Question 18

What would a pneumothorax CXR show?

Answer 18

Sharp, demarcating white line
Loss of lung markings
Tracheal deviation in tension AWAY
May progress to lobar collapse

Question 19

Ddx if cavitating lung lesion seen on CXR

Answer 19

Abscess (Staph./Klebsiella)
Neoplasm
Cavitation around pneumonia -> TB
Infarct
Rheumatoid nodule

Question 20

Ddx if hilar lymphadenopathy on CXR

Answer 20

Sarcoidosis
Tumours; mets, bronchial Ca, lymphoma
Infection; TB, AIDs, recurrent chest infections

Question 21

What would a heart failure CXR show?

Answer 21

A lveolar/interstitial shadowing
B lines - Kerley
C ardiomegaly
D upper lobe diversion
E ffusions
F luid in horizontal fissure

Question 22

Possible abnormal findings on AXR

Answer 22

Thumb-printing => IBD
Lead pipe => IBD (UC)
Large bowel dilation => toxic megacolon
Coffee bean => sigmoid volvulus
Embryo => caecal volvulus

Question 23

What is the structure to interpreting a CXR?

Answer 23

Basics
- PA/AP, name, DOB, date, previous comparisons

RIPE
- rotation, inspiration, penetration, exposure

ABCDE

• airways; trachea deviation
• breathing; lung markings. consolidation
• cardiac; cardiomegaly, air around?
• diaphragm; angles, gastric bubble, air under?
• everything else; bone fractures, breast, lymph nodes