Thoracic imaging 2

Question 1

The cardiac silhouette is the summation of?

Answer 1

Heart, pericardial contents and pericardium

Question 2

Cardiac failure must be differentiated from?

Answer 2

Cardiac disease

Question 3

Compare cardiac disease and failure

Answer 3

• A cardiac disease or murmur can be present for years without failure
• Failure is when disease gets so severe that heart function is compromised and can no longer compensate

Question 4

Does cardiomegaly occur in cardiac failure or disease?

Answer 4

• Cardiac disease can be present without cardiomegaly: moderate change in shape and/or size must be present to be detectable
But.. most dogs with cardiac failure have some degree of cardiomegaly

Question 5

Describe forwards HF

Answer 5

= output of the heart (pulmonary artery and aorta)

• Reduced CO
• Difficult to identify on radiographic studies

Question 6

Describe right sided backwards failure

Answer 6

Pressure in the vena cava increases (congestion) causing fluid to leak into body cavities (predominantly the abdomen)

• Hepatic congestion
• Ascites
• Pleural effusion

Question 7

Describe left sided backwards failure

Answer 7

Pulmonary venous congestion due to a build up of pressure or fluid which leads to leaking of fluid causing pulmonary oedema

Question 8

Which factors can affect the cardiac silhouette on a radiograph

Answer 8

• Recumbency: right vs left

- Breed variation

Question 9

How is the vertebral heart score calculated?

Answer 9

• Compare size of heart (sum of lung and short axis) to vertebral length (T4)
• Often considerable variation between breeds

Question 10

How might left sided heart disease appear on a radiograph?

Answer 10

• Tracheal elevation (to parallel to spine) and straightening of the caudal cardiac border due to left ventricular enlargement
• Left atrial enlargement or “tenting”
• May see bronchial compression caudal to carina
• Divergence of caudal mainstem bronchi to more than 60-90 degrees

Question 11

How might right sided heart disease appear on a radiograph?

Answer 11

• Increase in cardiac width and rounding of right side
• Increased R:L ratio
• Increased sternal contact: be aware that some breeds have this as a normal finding
• “Reverse D” shape on DV view as right side rounds out

Question 12

Describe the normal appearance of cranial and caudal lobar vessels on a dog/cat radiograph

Answer 12

• Cranial lobar vessels: usually not significantly wider than the proximal third of the fourth rib
• Caudal lobar vessels: usually not significantly wider than the ninth rib where they cross

Question 13

Describe cardiogenic (heart origin) pulmonary oedema

Answer 13

• Interstitial (early/mild) or alveolar (late/severe) perihilar/caudodorsal predisposition
• Left sided cardiomegaly often apparent
• May be pulmonary vascular enlargement
• Left sided heart failure

Question 14

Describe mitral valve disease

Answer 14

• Tends to be smaller breed dogs
• Typical pattern of progressive left atrial enlargement
• Ultimately pulmonary oedema (when in failure)

Question 15

Describe the radiographic features of dilated cardiomyopathy

Answer 15

• Often significant cardiomegaly if clinical (may be less obvious if deep chested)
• Significant left atrial +/- right sided enlargement

Question 16

Describe the different feline cardiomyopathies?

Answer 16

• Hypertrophic (HCM) (the most common)
• Dilated (DCM)
• Restrictive (RCM)
• Unclassified (UCM)
• Chamber enlargement less specific in cats
• May see more generalised cardiomegaly

Question 17

Describe pericardial effusion and its radiographic appearance

Answer 17

• Fluid within pericardial space (idiopathic/secondary to masses)
• Round and sometimes well-defined cardiac silhouette (especially on DV)
• Generally no-specific chamber enlargement evident
• Subtle evidence of cause may be apparent (heart based-mass)

Question 18

Describe pulmonic stenosis and its radiographic appearance

Answer 18

• Stenosis of pulmonary outflow tract (valve or another level)
• Can see post-stenotic bulge of the main pulmonary artery
• Beware as may see similar in normal dogs
• Sometimes small pulmonary vessels (only in very severe cases)
• Consequent right-sided enlargement due to pressure overload

Question 19

Describe a patent ductus arteriosus and its radiographic appearance

Answer 19

• Failure of foetal ductus arteriosus to occlude at birth
• Most common congenital cardiovascular abnormality in dogs
• Increased pulmonary flow, left sided enlargement and aortic enlargement

Question 20

Describe a persistent right aortic arch and its radiographic appearance

Answer 20

• Most common vascular ring anomaly in dogs
• Left displacement of trachea and deviation to left consistent sign
• May see ventral tracheal deviation and focal megaoesophagus