DIAGNOSTICS - Heart Diagnostic Imaging Flashcards
What can radiography of the heart be used to assess?
Heart size
Individual heart chamber enlargement
Evidence of congestive heart failure
Position of heart
What are the two orientations that should be used to radiograph the heart?
Right lateral view
Dorsoventral (DV) view
Identify the following features on this right lateral radiograph of the heart
Identify the following features on this dorsoventral (DV) radiograph of the heart
What size should a normal heart appear on a radiograph of a dog?
2/3 height of thorax
1/2-2/3 width of thorax
Take up 3-3.5 intercostal spaces
What size should a normal heart appear on a radiograph of a cat?
2/3 height of thorax
1/2-2/3 width of thorax
Take up 2-3 intercostal spaces
What can echocardiography be used to assess?
Internal structures of the heart
Myocardial function
Blood flow through the heart
What is echocardiography?
Ultrasound of the heart
What position should the patient be in for an echocardiogram?
Right followed by left lateral recumbency
What is hypostatic congestion?
Hypostatic congestion is the partial collapse of the lung by the heart and mediastinum when an animal is in lateral recumbency
How does the other lung compensate for hypostatic congestion?
The other lung will hyper inflate to compensate
Why should you scan the heart from the lower thoracic wall when an animal is in lateral recumbency?
You should scan the heart from the lower thoracic wall when an animal is in lateral recumbency as the apex of the heart will partially collapse the lower lung, improving image quality and you will avoid imaging the upper hyper inflated lung which would usually obscure the image
What is the best transducer to use for echocardiography?
Phased array transducer
How does the lumen of the heart appear in an echocardiogram?
Anechoic (black) due to the blood in the lumen
How does the cardiac muscle appear in an echocardiogram?
Echogenic (grey)
How does the pericardium appear in an echocardiogram?
Hyperechoic (white) with an acoustic shadow and reverberations
What is brightness (B-mode) echocardiography?
B-mode echocardiography produces a real-time grey-scale image of the heart.
What are the two main standard views that should obtained during echocardiography?
Right parasternal view
Left parasternal view
Which side of the heart is in the near field (top) of the ultrasound image in right parasternal views?
Right side of the heart
Which side of the heart is in the far field (bottom) of the ultrasound image in right parasternal views?
Left side of the heart
What are the three standard right parasternal short axis views of the heart that should be obtained during echocardiography?
Left ventricle
Mitral valve
Heart base
Which standard view of the heart is represented in this image?
Right parasternal short axis view of the left ventricle
Identify the labelled structures in this right parasternal short axis view of the left ventricle
Which standard view of the heart is represented in this image?
Right parasternal short axis view of the mitral valve
Identify the mitral valve in this right parasternal short axis view of the mitral valve
Which standard view of the heart is represented in this image?
Right parasternal short axis view of the heart base
Identify the labelled structures in this right parasternal short axis view of the heart base
What are the two standard right parasternal long axis views of the heart that should be obtained during echocardiography?
Left atrium and ventricle
Left ventricle and aorta
Which standard view of the heart is represented in this image?
Right parasternal long axis view of the left atrium and ventricle
Identify the labelled structures of this right parasternal long axis view of the left ventricle and atrium
Why can only long axis views be obtained when an animal is in left lateral recumbency?
The apex of the heart is naturally located slightly to the left of midline, so when the patient is placed in left lateral recumbency, the apex moves closer to the thoracic wall than it does when the patient is in right lateral recumbency. This means that short axis left parasternal images would be difficult to visualise and thus only long axis views can be achieved
What are the two standard left parasternal long axis views of the heart that should be obtained during echocardiography?
4-chamber
5-chamber
Which standard view of the heart is represented in this image?
Left parasternal long axis 4-chamber view
Identify the labelled structures of this left parasternal long axis 4-chamber view
What is Time-Motion (M-mode) echocardiography?
M-mode echocardiography produces a single-dimensional image of the contraction or movement of the heart structures over time
How is M-mode echocardiography performed?
M-mode is performed through manually placing a cursor line through the structures in the standard B-Mode image that you want to examine. The structures along the length of the cursor will then be displayed against time as a chart across the ultrasound screen
Which are four useful measurements that can be obtained in M-mode echocardiography?
Shortening fraction
Ejection fraction
E-point to septal seperation (EPSS)
Left atrial diameter
What is the shortening fraction?
The shortening fraction is the fractional change between the left ventricular end-diastolic diameter and the left ventricular end-systolic diameter which can be used to assess contractile function of the ventricle
Describe how the shortening fraction is calculated using M-mode echocardiography
To calculate the shortening fraction, a right parasternal short axis view of the left ventricle is used and the M-mode cursor is positioned so it bisects the left ventricle between the papillary muscles
What is suggested by a reduced shortening fraction?
A reduced shortening fraction suggests reduced ventricular contractility
What is suggested by an increased shortening fraction?
An increased shortening fraction would suggest compensatory hyper-contractility
What is normal shortening fraction range in dogs?
25 - 45%
What is normal shortening fraction range in cats?
30 - 55%
What is E-point to septal separation (EPSS)?
E-point to septal separation (EPSS) is the distance between the mitral valve and the interventricular septum
Describe how the E-point to septal separation (EPSS) is calculated using M-mode echocardiography
To calculate the end-point to septal separation (EPSS) a right parasternal short axis view of the mitral valve is used and the M-mode cursor is positioned so it bisects the mitral valve
What is the normal E-point to septal separation (EPSS) value in a healthy animal?
The E-point to septal separation (EPSS) value should be no more than 7mm in a healthy animal
What is indicated by a E-point to septal separation (EPSS) value above 7mm?
Indicative of left ventricular volume overload
Describe how left atrial diameter is calculated using M-mode echocardiography
To calculate the left atrial size, a right parasternal short axis view of the heart base is used and the M-mode cursor is positioned so it bisects the left atrium and the aorta to compare the diameter of the left atrium and aorta at systole
What is the normal ratio between left atrial diameter to aortic diameter in a dog?
1 : 1-1.4
What is the normal ratio between left atrial diameter to aortic diameter in a cat?
1 : 1.2 - 1.7
What is indicated by an increase in the ratio between left atrial diameter to aortic diameter?
An increase in the ratio between left atrial diameter and aortic diameter is indicative of atrial dilatation
What is the function of doppler ultrasound?
Doppler ultrasound allows for the visualisation of the direction and velocity of blood flow through the heart
What are the two types of doppler ultrasound
Colourflow doppler ultrasound
Spectral doppler ultrasound
How does colourflow doppler ultrasound depict blood flow through the heart?
Colourflow doppler depicts blood flow away from the transducer as blue, blood flow towards the transducer as red and turbulent blood flow as green
How does spectral doppler ultrasound depict blood flow through the heart?
Spectral doppler ultrasound depicts blood flow as a graph which depicts blood velocity and direction
