cardiac ultrasound

Question 1

what is ultrasound of the thoracic cavity limited by

Answer 1

• ribs (have to angle probe in intercostal spaces = small window)
• gas (causes reflection)
• ventilation (lung field moves with respiration)

Question 2

what can we use thoracic ultrasound to image

Answer 2

• heart (called echocardiography)
• lung surface
• pleura and pericardium
• lymph nodes, thymus and space occyupying lesions
• vascular structures (not limited to thorax)

Question 3

what are the terms used to describe the windows of cardiac imaging on ultrasound (where can you place probe to get image of heart)

Answer 3

parasternal window (left or right)
- found in lateral recumbency in dogs or standing in large animals
- through ribs
subcostal window
- under the ribcage

Question 4

what are the different axis views we use to image the heart

Answer 4

• long axis view (from base to apex)
• short axis view (across heart)

Question 5

what is B-mode

Answer 5

“bright mode”
- provides a real time slice through tissues
- routinely used for qualitative assessment of function
- measurement of chamber dimensions (LA)
- more sound reflected = brighter image

Question 6

what is M-mode

Answer 6

• measures movement along a single plain
• plots single plain against time
• used to assess cardiac function (contractility and valve function)

Question 7

what does a doppler ultrasound do

Answer 7

• picks up the change in frequency that occurs when sound is reflected by a moving object (blood or myocardium)
• stationary object = reflected sound is of same frequency
• spproaching object - frequency of reflected sound is increased
• retreating object= frequency of reflected sound is descreased

identifies velocity of blood flow (and direction)

Question 8

what is a spectral doppler

Answer 8

describes either:
- pulsed wave doppler: records velocity from a single location
- continuous wave dopple: records velocity along a specific line (similar to M mode)

flow is proprtional to pressure difference

Question 9

what is a colour flow doppler

Answer 9

• uses pulse wave doppler in multiple locations
• samples multiple areas
• limited by aliasing, but easier to overcome with software
• helps show things like regurgitation

Question 10

what are indications for cardiac ultrasound

Answer 10

assessment of:
- cardiac chamber size
- myocardial pathology
- myocardial function (contractility)
- valvular function and regurgitation (using doppler)
- vascular dysfunction

Question 11

what are the limitations of cardiac ultrasound

Answer 11

• air (limited area of imaging depenant on cardiac notch)
• bone ( limited imaging window and probe type, also os cordis in cattle)
• distance (especially in large animals)
• anatomy (forelimb may limit imaging angle)

Question 12

what are the standardised view of cardiac ultrasound (orientation)

Answer 12

• long and short axis views
• mainly taken from RIGHT HAND SIDE)
• in dogs and cats: subcostal to see aortic ejection and MV dysfunction
• in horses left sided lets you see left atrium and aortic outflow

Question 13

what view is this? label it

Answer 13

long axis view
Red: LV
yellow: MV
green: LA
blue: septum

Question 14

what view is this? what structures are seen

Answer 14

short axis

Question 15

should you be able to see the pericardium on Us

Answer 15

no, indicator of pericardial effusion

Question 16

what can you see with ultrasound of lungs

Answer 16

• can not visualise normal pulmonary architecture (gas filled = anechoic)
• can identify lung surface, pleura and pleural space
• can see lung consolidation
• useful to identify surface pathology (especially in large animals

why?
in a normal lung, sound does not penetrate a normal aerated lung. you can only visualise smooth, freely gliding surface as there is minimal fluid

Question 17

what colour is normal blood on ultrasound

Answer 17

white swirly