Clinical knowledge Flashcards
How many anterior ribs should be visible on a CXR?
5
What is the best type of projection used for CXRs?
PA (posterior to anterior)
Why are AP projections used for CXRs?
If the patient is too unwell to tolerate standing or leaving the bed
What is the issue with AP projections?
The quality is bad and they make the heart appear larger than it is
What is a pneumonic to assess the quality of CXRs?
RIPE
Rotation = clavicles equidistant from spinous processes? spinous processes vertically orientated against vertebral bodies?
Inspiration = are 5-6 ribs, costophrenic angles and lateral rib edges visible?
Projection = AP or PA?
Exposure = vertebrae visible behind the heart?
What is the ABCDE approach to CXRs?
Airways Breathing Cardiac Diaphragm Everything else
Why should you inspect the trachea in CXRs?
For evidence of deviation eg in pneumothorax or pleural effusion
What is the criteria for cardiomegaly in CXRs?
If the heart occupies more than 50% of the thoracic width on a PA CXR
What is pneumoperitoneum and state some possible causes of it
When free gas accumulates under the diaphragm causing it to lift
Bowel obstruction, appendicitis and diverticulitis are examples of causes
What is chilaiditi syndrome?
Abnormal positioning of the colon between the liver and diaphragm and can give false impression of pneumoperitoneum
Where is the PR interval between?
The start of the p wave to the beginning of the q wave
Where is the ST segment between?
The end of the S wave and the beginning of the T wave
Where is the QT interval between?
The start of the QRS complex and the end of the T wave
What does the T wave represent?
Ventricle repolarisation
What does each small square and each large square on ECG paper represent?
Small square = 0.04 secs
Large square = 0.2 secs
How can you calculate the rate of ECGs with regular rhythms?
Divide 300 by the number of large squares between each R-R interval
How can you calculate the rate of ECGs with irregular rhythms?
Number of R waves (on rhythm strip) x 6
Which leads give an inferior view of the heart?
Leads II, III and aVR
Which leads give an anterior view of the heart?
Leads V3 and V4
Which leads give a septal view of the heart?
Leads V1 and V2
Which leads give a lateral view of the heart?
Leads I, aVL, V5 and V6
Where is the normal cardiac axis between?
-30 and +90
What causes positive deflections on ECGs?
When direction of electrical activity moves towards a lead
On an ECG with a normal cardiac axis which leads would you expect to have the most positive and most negative deflection?
Lead II = most positive
Lead aVR = most negative
On an ECG with a normal cardiac axis what deflections would you expect in Leads I and aVF?
Lead I = positive
Lead aVF = positive
Using the quadrant approach (looking at QRS in leads I and aVF) what would you expect to see in RAD?
Lead I = negative
Lead aVF = positive
Using the quadrant approach (looking at QRS in leads I and aVF) what would you expect to see in LAD?
Lead I = positive
Lead aVF = negative
What is P mitrale and what causes it?
Bifid p waves caused by left atrial enlargement eg mitral stenosis
What is P pulmonale and what causes it?
Tall, peaked p waves caused by right atrial enlargement usually due to pulmonary hypertension
What is the criteria for a broad QRS complex?
> 120ms
What is the general trend for QRS complexes across chest leads in a normal ECG?
Becomes more positive
Describe what is seen on an ECG in atrial fibrillation
Tachycardia, irregularly irregular rhythm, no p waves
Describe what is seen on an ECG in atrial flutter
Regular fast atrial activity (around 300bpm)
Saw tooth pattern of p waves
What changes on an ECG can be seen from a STEMI?
Hyperacute t waves
ST elevation
T wave inversion
Pathological Q waves
What ECG changes do NSTEMIs cause?
ST depression and t wave flattening or inversion
What are the three different categories of supraventricular tachycardia?
Regular atrial = sinus tachycardia, atrial tachycardia and atrial flutter
Regular atrioventricular = AVRT or AVNRT
Irregular atrial = AF or atrial flutter (variable block)
Describe why AV nodal re entrant tachycardia occurs (AVNRT)
There is no accessory pathway
The AVN has one fast and one slow pathway and a premature atrial contraction whilst the fast pathway is in its refractory period means that it goes down the slow pathway
This causes a continuous re entrant circuit causing increased stimulation of the ventricles
What can be seen on an ECG in AVNRT?
Tachycardia, QRS narrow <120ms, no p waves as buried in QRS
What is AV re entrant tachycardia?
Tachycardia due to an accessory pathway
Give an example of AVRT and the ECG changes that it causes
Wolf parkinson white
Short PR interval <120, wide QRS>110 and slurred delta wave at the start of the QRS complex
What does ventricular tachycardia look like on an ECG?
Regular, broad complex tachycardia with uniform QRS complexes within each lead
What does ventricular fibrillation look like on an ECG?
Chaotic irregular deflections
No identifiable p waves, QRS complexes or t waves
What are two causes of RBBB?
PE and IHD
What ECG changes does RBBB cause?
Broad QRS>120ms
M shaped QRS in V1-3
Widened slurred S wave in V6
(MaRRoW)
What ECG changes does LBBB cause?
Broad QRS>120ms
Dominant S wave in V1 “W”
Broad R wave in V6 “M”
(WiLLiaM)
What is first degree AV block?
PR interval >200ms
What is mobitz 1 second degree AV block?
Progressive prolongation of PR interval until a non conducted p wave
What is mobitz II second degree AV block?
Intermittent non conducted p wave without prolongation of PR interval
What is third degree AV block?
Complete heart block
Severe bradycardia
No link between p waves and QRS complexes
What ECG changes do hyper and hypokalaemia cause?
Hyperkalaemia = flattened p waves, wide QRS and tall, tented t waves Hypokalaemia = flattening of t waves and QT prolongation
What ECG changes do hyper and hypocalcaemia cause?
Hypercalcaemia = QT shortening Hypocalcaemia = QT prolongation
What is a normal QT interval?
0.33-0.44 secs
What ECG changes can hypothermia cause?
J waves, prolonged QRS and PR and ventricular ectopics
What ECG changes does pericarditis cause?
Widespread diffuse saddle shaped ST elevation
How can you tell between the JVP and carotid pulse?
JVP = a double waveform eg two pulses but the carotid artery has one for each cardiac cycle
JVP isnt easy to palpate but the carotid is
Where is the JVP located
Between the two heads of the sternocleidomastoid (sternal and clavicular heads)
How do you measure the JVP and where should it be located?
Assess the vertical distance between the sternal angle and the top of the pulsation point (shouldnt be >3cm)
What causes raised JVP?
Venous hypertension due to right sided heart failure, tricuspid regurg or constrictive pericarditis
What causes the first and second heart sounds?
First = closure of mitral and tricuspid valves Second = closure of aortic and pulmonary valves
Describe aortic stenosis
Ejection systolic crescendo decrescendo
Narrow pulse pressure
Radiates to carotids
Louder on expiration and when the patient is sat forwards
Describe aortic regurgitation
Early diastolic
Collapsing pulse
May have corrigans sign = visibly exaggerated pulsing carotids due to hyperdynamic circulation
Describe mitral stenosis
Mid diastolic
Loudest at apex
Low pitched rumbling
Describe mitral regurgitation
Pan systolic
Loudest in mitral area and when patient is in left lateral position
Where do you auscultate each of the 4 valves?
Aortic valve = 2nd right IC space right sternal border
Pulmonary valve = 2nd left IC space left sternal border
Tricuspid valve = 4th IC space left sternal border
Mitral valve = 5th IC space left mid clavicular line
