Cardiac Ultrasound

Question 1

Describe how ultrasound can be used to examine the heart and indications for its use

Answer 1

Ultrasound can also be used to assess the thoracic cavity and lung disease

Question 2

Describe how cardiac images are obtained

Answer 2

1. Parasternal window (left or right) in lateral recumbency in dogs - ‘tables with hole’ or standing in large animals
2. Subcostal window = under ribcage, image heart thro liver (small animal)
3. Long axis view = from base to apex
4. Short axis view = across heart

Question 3

Explain how B mode ultrasonography is used

Answer 3

· Provides a real time ‘slice’ through tissues

· Routinely used for qualitative assessment of function

· Measurement of chamber dimensions (LA) esp left atrium

· Bulk of horse investigation in B mode

Question 4

Explain how M mode ultrasonography is used

Answer 4

1. Measures movement along a single plain
2. Plots single plane against TIME
3. Used to assess cardiac function
   Contractility (fractional shortening) - % decrease in chamber size as heart contracts in systole
   Valve movement
4. More quantitative measurements

Question 5

List indications for ultrasound for cardiac ultrasound

Answer 5

Assessment of
- Cardiac chamber size
- Myocardial pathology
- Myocardial function (eg contractility)
- Valvular function and regurgitation (using Doppler)
- Vascular dysfunction

Question 6

Describe the limitations of cardiac ultrasound

Answer 6

1. air = limited area of imaging dependant on cardiac notch
2. bone = can’t penetrate rib, limited imaging window + probe size
3. distance = esp in large animals bet probe + opp side of heart
4. anatomy = forelimb limit imaging angle, horses tend to tense triceps = decrease cardiac window

Question 7

Recognise the internal cardiac structures on standardised images of the heart

Answer 7

View lecture notes

Question 8

Explain the indications for Doppler ultrasound examination

Answer 8

Doppler can be used to assess blood flow

Need to know normal direction of flow
o Document abnormal movement

o Backflow = abnormality
· Colour flow to map size of jet

o Green regurgitant jet
· Spectral (CW) to measure pressure differences

Question 9

Explain how a doppler works during an ultrasound

Answer 9

The change in frequency that occurs when sound is reflected by a moving object

Applies to blood or myocardium (tissue Doppler)

Stationary object – reflected sound is of same frequency

Approaching object – frequency of reflected sound is increased

Retreating object – frequency of reflected sound is decreased

Identifies velocity of blood flow (and direction)

Question 10

Outline what the spectral doppler measures

Answer 10

Pulsed wave
Records velocity from a single location

Continuous wave
	Records velocity along a specific line
		Similar to M-mode

Colour flow Doppler
	Records velocity in a specific area

Question 11

List indications for ultrasound of the lungs pleura and pericardium

Answer 11

Pericardium
detection of pericardial effusion
fluid between visceral and parietal pericardium

Question 12

Describe normal ultrasonographic appearance of the lungs pleura and pericardium

Answer 12

Can not visualise NORMAL pulmonary architecture
Gas filled

Lungs
Sound does not penetrate normal aerated lung.
Only visualise smooth, freely gliding surface
Minimal fluid in pleural cavity
Normal to have a bit of fluid lining

Pericardium
Cannot usually be visualised

Question 13

List the limitations of ultrasonography of the lungs pleura and pericardium

Answer 13

Ribs = small imaging window

Gas = ultrasound beam cant pass thro, imaging window in cardiac notch

Ventilation = lung field moves with respiratory cycle