X-rays and ECG Flashcards
What is the structure to interpreting an ECG?
Basics
- name, DOB, time, indication, whether chest pain present, calibration (x -> 25mm/s)
Rate, rhythm, axis
PQRST waveforms
Describe rate
Bradycardia < 60
Normal 60-100
Tachycardia > 100
Describe rhythm
Count QRS peaks on strip and x 6
Regular or irregular
May be regularly or irregularly irregular
Describe axis
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)
What do any p-wave abnormalities suggest?
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
What do any QRS abnormalities suggest?
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
How do you differentiate between L and RBBB?
LBBB
=> WiLLiaM, V1/6
RBBB
=> MaRRoW, V1/6
What do any PR interval abnormalities suggest?
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)
What are the two types of 2nd degree HB?
Mobitz type 1
=> increasing PR until dropped QRS + repeat
Mobitz type 2
=> randomly dropped QRS every 2/3 p-waves (2:1/3:1)
What would the ECG of a hyperkalaemic pt show?
- Tented T-waves; > 5.5mmol/L
- Flat p-waves; >6.5mmol/L
- Broad QRS + bradycardia; > 7.5mmol/L
Tx of hyperkalaemia
10ml 10% calcium gluconate/chloride
10U insulin
50ml 50% dextrose
What would the ECG of a hypokalaemic pt show?
U waves, ST depression, flattened T-waves, prolonged PR interval, long-QT syndrome
Tx: K+!
What do any ST segment abnormalities suggest?
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
What do any QT interval abnormalities suggest?
Long QT syndrome; >0.44 (m) >0.46 (f)
= acquired: hypomangnesaemia, hypokalaemia, amiodarone
= congenital
What do any T wave abnormalities suggest?
Tall; >5mm limb leads + >10mm chest leads
=> hyperkalaemia, hyperacute MI
Inverted (only normal in VI + III)
=> ischaemia, BBB, PE, LVH
What would a pneumonia CXR show?
Alveolar shadowing
?Air bronchograms
Usually unilateral
What would a pleural effusion CXR show?
Homogenous shadowing
Fluid level (meniscus)
Loss of costophrenic angles
Transudate vs exudate
What would a pneumothorax CXR show?
Sharp, demarcating white line
Loss of lung markings
Tracheal deviation in tension AWAY
May progress to lobar collapse
Ddx if cavitating lung lesion seen on CXR
Abscess (Staph./Klebsiella) Neoplasm Cavitation around pneumonia -> TB Infarct Rheumatoid nodule
Ddx if hilar lymphadenopathy on CXR
Sarcoidosis
Tumours; mets, bronchial Ca, lymphoma
Infection; TB, AIDs, recurrent chest infections
What would a heart failure CXR show?
A lveolar/interstitial shadowing B lines - Kerley C ardiomegaly D upper lobe diversion E ffusions F luid in horizontal fissure
Possible abnormal findings on AXR
Thumb-printing => IBD Lead pipe => IBD (UC) Large bowel dilation => toxic megacolon Coffee bean => sigmoid volvulus Embryo => caecal volvulus
What is the structure to interpreting a CXR?
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
